tion. A high-flow pump is especially helpful, maintaining a high flow rate without excessive pressure, which would worsen extravasation. Hypotensive anesthesia, placing epinephrine in the arthroscopic fluid, and electrocautery or other thermal device for hemostasis all aid in visualization for effectively performing the excision.
Hip instability can occur but is much less common than seen in the shoulder. There are several reasons, but, most principally, it is due to the inherent stability provided by the constrained ball-and-socket bony architecture of the joint. Also, the labrum is not as critical to stability of the hip as it is in the shoulder as there is no true capsulolabral complex. On the acetabular side, the capsule attaches directly to the bone, separate from the acetabular labrum.30 An entrapped labrum has been reported as a cause of an irreducible posterior dislocation and a Bankart type detachment of the posterior labrum has been identified as the cause of recurrent posterior instability.31,32 These circumstances have only rarely been reported but may be recognized with increasing frequency as our understanding of and intervention in hip injuries evolves.
Instability may occur simply due to an incompetent capsule. This is seen in hyperlaxity states and less often encountered in athletics. The most common cause is a collagen vascular disorder such as Ehlers-Danlos syndrome. With normal joint geometry, thermal capsular shrinkage has continued to meet with successful results (Fig. 45-27). If subluxation or symptomatic instability is due to a dysplastic joint, it is likely that bony correction for containment is necessary to achieve stability.
Based on this author's observations, posterior instability has been found to be associated with macrotrauma. This is due to the characteristic mechanisms of injury, including dashboard injuries and axial loading of the flexed hip encountered in collision sports. Atraumatic instability or instability due to repetitive microtrauma is anterior and develops when the normally occurring anterior translation of the femoral head exceeds the physiologic threshold and becomes pathologic. Symptoms may be due to primary instability, secondary intra-articular damage, or a combination of both.
The reported complication rate associated with large hip arthroscopy series ranges from 1.3% to 6.4%.33-35 Most of these are minor or transient, but a few major complications have been reported. Traction neuropraxia is usually associated with prolonged procedures and excessive traction but can occur even when staying within established guidelines. With normal precautions, it is expected that the condition should be transient and recovery complete. Direct trauma to the major neurovas-cular structures should be avoidable with thoughtful orientation to the landmarks and careful technique in portal placement. The consequences of these types of injuries are generally devastating. Small branches of the lateral femoral cutaneous nerve invariably lie around the anterior portal. Even with careful technique, there is a 0.5% chance of incurring a small patch of reduced sensation in the lateral thigh due to instrumentation around one of these branches.
Potentially life-threatening intra-abdominal extravasation of fluid has been reported.36 This is generally attributed to fresh acetabular fractures, extra-articular procedures, and prolonged operating times.34 It is imperative that the surgeon be cognizant of the balance of ingress and egress of fluid throughout the operative procedure.
It is likely that the most common complication, which goes largely unreported, is iatrogenic intra-articular damage. Even with careful attention to the details of the procedure, this cannot be entirely avoided. However, it can be minimized and emphasizes the importance of meticulous technique in performing the procedure.
Hip joint injuries in athletes may go unrecognized for a protracted period of time, most commonly diagnosed as a strain. With an increase in awareness of intra-articular disorders, these problems are now being diagnosed earlier. However, much remains to be understood regarding the pathogenesis and natural history of many of these lesions that may influence the results of both surgical and conservative management. Nonetheless, arthroscopy has defined numerous sources of intra-articular hip pathology. In many cases, operative arthroscopy has met with significant success. For some, arthroscopy offers a distinct advantage over traditional open techniques, but for many, arthroscopy offers a method of treatment where none existed before. With this procedure, there are three important principles that must be thoroughly considered. First, a successful outcome is dependent on proper patient selection. A technically well-performed procedure will fail when performed for the wrong reason, which may include failure of the procedure to meet the patient's expectations. Second, the patient must be properly positioned for the procedure to go well. Poor positioning will ensure a difficult procedure. Third, simply gaining access to the hip joint is not an outstanding technical accomplishment. The paramount issue is that the joint must be accessed in as atraumatic a fashion as possible. Because of its constrained architecture and dense soft-tissue envelope, the potential for inadvertent iatrogenic scope trauma is significant and, perhaps to some extent, unavoidable. Thus, every reasonable step should be taken to keep this concern to a minimum by performing the procedure as carefully as possible and being certain that it is performed for the right reasons.
1. Byrd JWT, Jones KS: Hip arthroscopy in athletes. Clin Sports Med 2001;20:749-762.
2. Byrd JWT: Physical examination. In Byrd JWT (ed): Operative Hip Arthroscopy, 2nd ed. New York, Springer, 2005, pp 36-50.
3. Allen WC, Cope R: Coxa saltans: The snapping hip revisited. J Am Acad Orthop Surg 1995;3:303-308.
4. Byrd JWT, Jones KS: Diagnostic accuracy of clinical assessment, MRI, gadolinium MRI, and intraarticular injection in hip arthroscopy patients. Am J Sports Med 2004;32:1668-1674.
5. Byrd JWT: The supine approach. In Byrd JWT (ed): Operative Hip Arthroscopy, 2nd ed. New York, Springer, 2005, pp 145-169.
6. Sampson TG: The lateral approach. In Byrd JWT (ed): Operative Hip Arthroscopy, 2nd ed. New York, Springer, 2005, pp 129-144.
7. Dienst M, Godde S, Seil R, et al: Hip arthroscopy without traction: In vivo anatomy of the peripheral hip joint cavity. Arthroscopy 2001;17:924-931.
8. Dienst M: Hip arthroscopy without traction. In Byrd JWT (ed): Operative Hip Arthroscopy, 2nd ed. New York, Springer, 2005, pp 170-188.
9. Byrd JWT, Pappas JN, Pedley MJ: Hip arthroscopy: An anatomic study of portal placement and relationship to the extraarticular structures. Arthroscopy 1995;11:418-423.
10. Byrd JWT: Avoiding the labrum in hip arthroscopy. Arthroscopy
11. Byrd JWT: Hip arthroscopy for post-traumatic loose fragments in the young active adult: Three case reports. Clin J Sport Med 1996;6:129-134.
12. McCarthy JC, Bono JV Wardell S: Is there a treatment for synovial chondromatosis of the hip joint? Arthroscopy 1997; 13:409410.
13. Medlock V Rathjen KE, Montgomery JB: Hip arthroscopy for late sequelae of Perthes disease. Arthroscopy 1999;15:552-553.
14. Byrd JWT: Labral lesions: An elusive source of hip pain: Case reports and review of the literature. Arthroscopy 1996;12:603-612.
15. Lage LA, Patel JV Villar RN: The acetabular labral tear; an arthroscopic classification. Arthroscopy 1996;12:269-272.
16. Farjo LA, Glick JM, Sampson TG: Hip arthroscopy for acetabular labrum tears. Arthroscopy 1997;13:409-410.
17. Santori N, Villar RN: Acetabular labral tears: Result of arthroscopic partial limbectomy. Arthroscopy 2000;16:11-15.
18. Byrd JWT, Jones KS: Inverted acetabular labrum and secondary osteoarthritis: Radiographic diagnosis and arthroscopic treatment. Arthroscopy 2000;16:417.
19. Byrd JWT: Hip arthroscopy: Evolving frontiers. Op Tech Sports Med 2004;14:58-67.
20. Byrd JWT: Lateral impact injury: A source of occult hip pathology. Clin Sports Med 2001;20:801-816.
21. Byrd JWT, Jones KS: Microfracture for grade IV chondral lesions of the hip. Arthroscopy 2004;20(SS-89):41.
22. Gray AJR, Villar RN: The ligamentum teres of the hip: An arthroscopic classification of its pathology. Arthroscopy 1997;13:575-578.
23. Byrd JWT, Jones KS: Traumatic rupture of the ligamentum teres as a source of hip pain. Arthroscopy 2004;20:385-391.
24. Farjo LA, Glick JM, Sampson TG: Hip arthroscopy for degenerative joint disease. Arthroscopy 1998;14:435.
25. Villar RN: Arthroscopic debridement of the hip: A minimally invasive approach to osteoarthritis. J Bone Joint Surg Br 1991;73(Suppl II):170—171.
26. Santori N, Villar RN: Arthroscopic findings in the initial stages of hip osteoarthritis. Orthopedics 1999;22:405-409.
27. Byrd JWT, Jones KS: Prospective analysis of hip arthroscopy with five year follow up. Paper presented at the AAOS 69th Annual Meeting, February 14, 2002, Dallas, TX.
28. Byrd JWT: Indications and contraindications. In Byrd JWT (ed): Operative Hip Arthroscopy, 2nd ed. New York, Springer, 2005, pp 6—35.
29. Byrd JWT: Arthroscopy of select hip lesions. In Byrd JWT (ed): Operative Hip Arthroscopy. New York, Thieme, 1998, pp 153—170.
30. Seldes RM, Tan V Hunt J, et al: Anatomy, histologic features, and vascularity of the adult acetabular labrum. Clin Orthop 2001;382:32-40.
31. Paterson I: The torn acetabular labrum: A block to reduction of a dislocated hip. J Bone Joint Surg Br 1957;39:306-309.
32. Dameron TB: Bucket-handle tear of acetabular labrum accompanying posterior dislocation of the hip. J Bone Joint Surg Am 1959;41: 131-134.
33. Clarke MT, Arora A, Villar RN: Hip arthroscopy: Complications in 1054 cases. Clin Orthop 2003;406:84-88.
34. Sampson TG: Complications of hip arthroscopy. Clin Sports Med 2001:20;831-835.
35. Byrd JWT: Complications associated with hip arthroscopy. In Byrd JWT (ed): Operative Hip Arthroscopy, 2nd ed. New York, Springer, 2005, pp 229-235.
36. Bartlett CS, DiFelice GS, Buly RL, et al: Cardiac arrest as a result of intraabdominal extravasation of fluid during arthroscopic removal of a loose body from the hip joint of a patient with an acetabular fracture. J Orthop Trauma 1998;12:294-300.
Physical Examination and Evaluation
Timothy C. Wilson
In This Chapter
Examination of specific ligaments Patellofemoral exam Meniscus exam Multiligamentous knee injuries
The clinical examination of the knee begins with a thorough history that focuses on the presenting symptoms and mechanism of injury. Questions should be asked regarding the onset and duration of symptoms. The location and quality of pain should be ascertained as well as the presence of any previous injuries or history of surgery. It is important to document the presence of swelling, mechanical symptoms, and instability. Mechanical symptoms may include locking and catching. Giving way may be the patient's description of instability. Many patients who experience a "pop" in their knee at the time of injury will have an anterior cruciate ligament (ACL) tear. In many cases, the history itself will direct the examiner toward the correct diagnosis.
The mechanism of injury provides useful information with regards to the direction and degree of injury. Ligament injuries are the result of forces from the opposite direction. For example, an anterior blow to the knee may cause a posterior knee dislocation. This injury pattern is commonly seen in "dashboard knee." Anterior dislocations commonly occur from extreme knee hyperextension. This happens when an anterior force occurs to the tibia against a fixed foot, and the femur is forced posterior to the tibia. Medial and lateral ligament injuries are most likely to occur from valgus and varus forces, respec-tively.2 Knowledge of each patient's mechanism of injury will be useful in determining which structures may be injured and the potential risk of associated injuries. In summary, the history can lead the examiner to a specific area to inspect and improve the ability to correctly diagnose.
A thorough examination of the knee involves a systematic approach. Having the patient relax is of utmost importance. The best physical examination can sometimes be obtained immediately after the injury before significant swelling and pain preclude a relaxed examination. It is helpful to examine the uninjured knee first not only to serve as a baseline, but also to gain the confidence of the patient. The least painful tests should be performed before progressing to the more painful examination techniques.
The patient's gait pattern should be inspected. An antalgic gait is demonstrated by a shortened stance phase and will confirm the involved extremity. During the stance phase the presence of a varus thrust should be noted if present. A short leg gait may be observed, and this can be noted by measuring for a leg length discrepancy. The clinical alignment of the limb should be observed for genu varus or valgus. This is measured by placing a goniometer on the patella and measuring the angular alignment of the femur in relation to the tibia. This measurement differs from the radiographic measurement of the mechanical axis.
The physical examination of the knee includes an inspection for any soft-tissue swelling or joint effusion (Fig. 46-1). It is important to distinguish between these two types of fluid accumulation. Fluid that is intra-articular signifies an injury to the joint itself. Common causes of an effusion include an ACL tear, patellar dislocation, or osteochondral injury. The finding of a bal-lotable patella is a sign of an effusion. Another sign of an effusion is the loss of the normal skin dimple that is visible just distal to the vastus medialis obliquus insertion on the patella. Prepatella swelling may be from a bursitis. Other soft-tissue swelling may be associated with extra-articular ligament tears and sprains. For example, a medial collateral ligament sprain may present with medial soft-tissue swelling. The ability to distinguish an effusion from soft-tissue swelling is an important aspect of the physical examination.
The range of motion of the knee should be measured. A goniometer can be used to measure the amount of knee flexion and extension. The knee should be evaluated for hyperextension as well. Both knees should always be measured as asymmetry may be a sign of injury. A locked knee is a knee with the inability to fully extend because of a mechanical block such as from a bucket handle meniscus tear or a loose body.
Measurements should be taken of the girth of the quadriceps muscle. Quadriceps atrophy is commonly seen after surgery or
• The physical examination of the knee has been described as an art and a science.1
• The purpose of the examination is to arrive at the correct diagnosis.
• A complete patient history must be combined with a thorough physical examination in order to direct treatment.
• Additional tests such as radiographs, magnetic resonance imaging, bone scans, and angiography are sometimes used to provide information in the evaluation of a knee injury.
a chronic injury. The measurement is taken at a set distance from either the patella or joint line and the two knees are compared to one another. Subsequent measurements can be made to follow a patient's progress with rehabilitation.
Palpation is an essential part of all examinations. The bony landmarks should be assessed for tenderness. Joint line tenderness is sensitive for the diagnosis of a meniscus tear. Sometimes a meniscal cyst may be visible and palpable in the joint line. A medial patellofemoral plica can be palpable medially, just above the joint line, and is sometimes tender as it is compressed between the examiner's fingers and the medial femoral condyle. The inferior pole of the patella, patellar tendon, and tibia tubercle are common areas of tenderness in athletes with anterior knee pain. Lateral patellofemoral compression may be associated with tenderness of the lateral patellar facet. Other common areas of tenderness include the iliotibial band, pes anserine bursa, and quadriceps. Crepitation of the knee joint as it goes through a range of motion is a common sign of patellofemoral chondromalacia. The knee should be assessed for warmth. A normal knee should always feel cooler to the touch than the surrounding musculature. The back of the examiner's hand may be used to detect subtle temperature differences. Synovitis is a common cause of a subtle increase in temperature of the knee.
In the acute setting, swelling and pain often prevent a detailed ligament examination. However, the best possible assessment should be obtained. Gross instability to varus or valgus testing in extension suggests injury to one or both cruciate ligaments, the joint capsule, and the associated collateral ligament. If the joint capsule has been disrupted, there may not be an effusion. Flexion is often not possible because of pain. This precludes anterior and posterior drawer testing. The information obtained from the physical examination should be correlated with the history and mechanism of injury.
The four main ligamentous structures include the ACL, posterior cruciate ligament (PCL), medial collateral ligament (MCL) with the posteromedial capsule, and the posterolateral corner (PLC). The PLC is composed of the lateral collateral ligament, popliteus tendon, popliteofibular ligament, arcuate ligament, fabellofibular ligament, and the posterolateral joint capsule. It is important to specifically examine each of the four elements carefully. Magnetic resonance imaging should not be extensively relied on because the accuracy of that test is diminished without clinical correlation.
The ACL serves as the primary restraint to anterior translation of the tibia in relation to the femur. It provides 86% of the resistance to anterior translation.3 The ACL also serves as a secondary stabilizer to varus, valgus, and rotational stresses about the knee.4 The most reliable and sensitive test for assessing ACL deficiency is the Lachman test (Fig. 46-2). To perform the test, the examiner stabilizes the femur with one hand and performs an anterior drawer with the other hand on the tibia. The knee is held in 20 to 30 degrees of flexion with neutral rotation. The Lachman test measures laxity, and the examiner should appreciate the quality of an endpoint. Any increased translation is a positive result and is graded I, II, and III. A grade I is 0 to 5 mm of translation. A grade II is 6 to 10 mm, and a grade III is greater than 10mm and lacks a firm endpoint. In multiple-ligament injured knees, this test is more difficult to perform. For example, PCL-deficient knees can mislead the examiner because of the abnormal translation. Also, a complete MCL disruption can give a false-positive result on the Lachman test if care is not taken to perform the test in neutral rotation. This results from the antero-medial rotational instability secondary to MCL disruption.
The ACL does more than just prevent anterior translation of the tibia on the femur. It also serves as the principal restraint to anterolateral rotatory instability. Tests that are designed to examine this elicit the pivot-shift phenomenon. These tests include Slocum's anterior rotatory drawer test, the Hughston-Losee jerk test, and the MacIntosh lateral pivot shift test. All these tests are performed with a valgus force during flexion and extension of the knee to elicit subluxation or reduction of the tibia on the femur. In an ACL-deficient knee, as the knee goes from flexion to extension, the iliotibial band is anterior to the center of rotation of the knee and subluxates the tibia anteriorly. The tibia is reduced as the knee goes back into flexion. These tests are difficult to perform in the acute setting because of pain and guarding.
The flexion rotation test combines elements of the Lachman and the pivot-shift tests. The patient is supine with the knee in neutral rotation. The leg is lifted up and the tibia subluxates anteriorly with the femur posteriorly and externally rotated. The knee is then flexed with a valgus stress and anterior force on the proximal tibia. This results in the tibia moving posteriorly as the femur internally rotates, which reduces the tibia.5 The examiner should become proficient in the Lachman test and at least one of the pivot-shift tests.
Injuries to the PCL are sometimes subtle, and careful attention should be paid to a complete knee ligament examination. The PCL serves as the primary restraint to posterior translation of the tibia.3 The physical examination of the PCL includes the posterior drawer test, posterior sag sign, and quadriceps active test. The most sensitive test is the posterior drawer test (Fig. 46-3). The posterior drawer test is performed with the knee in 90 degrees of flexion. The examiner's thumbs are placed on the joint line and a posterior drawer is applied. The anterior tibiofemoral step-off is important to note when performing this test. Normal step-off is 8 to 10 mm (tibia anterior to the femur with the knee flexed 90 degrees). This test is graded according to the amount of translation with a posteriorly directed force. A positive test has increased translation. With a grade I, the tibia remains anterior to the femoral condyles. A grade II results in the tibia being equal to the femoral condyles, and with a grade III, the tibia can be subluxated posterior to the femoral condyles and lacks a firm endpoint. Grade III laxity on the posterior drawer test is suggestive of a clinically significant injury and usually involves injury to the secondary restraints as well.
Medial Collateral Ligament
The MCL is the primary restraint to a valgus knee stress at 20 to 30 degrees of flexion. It is also a secondary restraint to ante-
Figure 46-3 Posterior drawer test. The knee is placed in 90 degrees of flexion. A posterior force is applied to the femur. The amount of posterior displacement is assessed.
rior translation. Testing is performed by applying a valgus stress at 20 to 30 degrees flexion. This test is graded according to the amount of joint line opening in millimeters and the presence of an endpoint. Grade I is less than 5 mm of opening, grade II is 6 to 10 mm, and a grade III is greater than 10 mm. The knee is also tested in full extension. Opening to valgus testing in full extension implies damage to the posteromedial capsule in addition to the superficial medial collateral ligament6 (Fig. 46-4). The posteromedial capsule is part of the deep MCL and may need to be repaired or reconstructed in some cases.
For patients with medial collateral ligament injuries, it is important to document the precise location of the tenderness. This can help differentiate the location and severity of the injury. Although most medial collateral ligaments may do well with nonoperative treatment, a subset of MCL injuries with complete disruption off the tibia may have an indication for a direct anatomic repair. Patients with a complete disruption of the MCL off the tibia have been shown to have tenderness over the tibia as opposed to the femoral side of the MCL.7
The posterolateral corner resists varus and rotational forces to the knee. The anatomic structures of the PLC can be divided into three layers. Layer 1 is composed of the iliotibial band and the biceps femoris tendon. Layer 2 consists of the lateral reti-naculum and lateral patellofemoral ligaments. Layer 3 is the deepest and contains the lateral collateral ligament or fibular collateral ligament, the fabellofibular ligament, the popliteus, the arcuate complex, and the important popliteofibular ligament. Testing of the PLC consists of varus stress to the knee at 0 and 30 degrees. Increased external rotation of the tibia at 30 and 90 degrees is tested and compared to the contralateral knee. Increased external rotation at 30 degrees that decreases at 90 degrees suggests an isolated injury of the posterolateral corner. If the external rotation does not decrease at 90 degrees, then there may also be an injury to the PCL. Other tests include the posterolateral drawer test, external rotation drawer test (dial test), and reverse pivot-shift test. The posterolateral drawer test is performed with an anterior drawer at 90 degrees of knee flexion. If the posterolateral structures are torn, then the knee will have increased translation with internal rotation as compared to neutral rotation. The dial test is performed with the hips and knees flexed. Both lower extremities are evaluated by externally rotating the feet of the patient. Increased external rotation signifies injury of the posterolateral complex. A variant of this test is the external rotation recurvatum test. In this test, the examiner holds both feet by the toes and if the relaxed knee falls into recurvatum, it is a positive test result. The reverse pivot-shift test begins with the knee flexed and the tibia externally rotated. The knee is then passively extended, and when posterolateral laxity is present, a sudden shift will occur at 20 to 30 degrees of flexion as the posteriorly subluxated lateral side of the tibia abruptly reduces.
Increased opening to varus stress at 30 degrees without opening at 0 degrees or other signs of a PLC injury suggests an isolated tear of the fibular collateral ligament.8 Failure to diagnose and treat an injury of the posterolateral corner of the knee in a patient who has a tear of the ACL or PCL can result in failure of the reconstructed ligament.
The patellofemoral joint has many examination tests specific to evaluate for patellofemoral disorders. The tracking of the patella as the knee goes from a flexed to an extended position may take the form of an upside down letter J. The positive J sign suggests a tight lateral retinaculum. As previously described, the quadriceps angle or Q angle should be measured along with the lower extremity alignment. The examiner should also assess for crepi-tus, patellar apprehension, and specific areas of tenderness. A maneuver has been described that can detect patella instability, with the knee flexed 30 degrees and applying a distal lateral force. Increased patellar translation with a softer endpoint compared with a normal contralateral knee may suggest disruption of the medial patellofemoral ligament.9
There are many different tests used to assess for meniscus tears. The most sensitive test is joint line tenderness.10 Other tests attempt to produce the symptoms of a torn meniscus such as McMurray's test, Apley's grind test, and others. McMurray's test is performed with passive motion from flexion to extension with internal and external rotation. A palpable click on the joint line is a positive test. Apley's grind test is performed with the patient prone and the knee flexed 90 degrees. Compression of the tibiofemoral joint will elicit pain, whereas distraction of the joint will cause diminished pain in a positive result of the Apley test. A bucket handle tear that is displaced may present with true locking of the knee. True locking of the knee is the inability of the patient to be able to fully extend the knee because of a mechanical block.
The initial diagnosis of a knee dislocation or multiple-ligament knee injury is an orthopedic emergency. Although some knee dislocations present with obvious deformity, most multiple-ligament knee injuries spontaneously reduce. One must have a high index of suspicion for these injuries. The patient's history provides essential information regarding the mechanism of injury and potential associated injuries. The direction of the force to the knee and the position of the leg are important variables. Contact versus noncontact injury is worth documenting. A high-energy motor vehicle accident is important to differentiate from a sports-related dislocation because of the greater incidence of severe soft-tissue injury and associated injuries.11,12
Vascular injuries, open dislocations, irreducible dislocations, and compartment syndromes require prompt diagnosis and immediate treatment. Open dislocations must be reduced with subsequent irrigation and débridement in the operating room and be treated with intravenous antibiotics for 48 hours. Soft-tissue wounds should be evaluated for problems with closure because plastic surgery consultation is sometimes necessary. Pos-terolateral knee dislocations may present as an irreducible dislocation (Fig. 46-5). The medial femoral condyle may become buttonholed through the medial retinaculum and present with the dimple sign.13 This particular type of dislocation may require open reduction. Prolonged dislocation in this position has been associated with skin necrosis. Compartment syndrome must always be ruled out and emergent fasciotomies are required when this condition exists or is impending. A detailed neu-rovascular examination follows the visual inspection.
The initial assessment of a multiligamentous knee injury must include a thorough and expedient physical examination with particular attention directed to the vascularity of the extremity. Vascular injuries should be ruled out immediately. Vascular injuries can occur with all types of dislocations. The risk of arte-
rial injury with a knee dislocation is between 10% and 64%.14 Green and Allen15 reported rupture of the artery to be as high as 44% with posterior dislocations. Anterior dislocations are associated with arterial injury in as many as 39%, and the incidence with medial is reported at 25% and lateral at 6%.
The dorsalis pedis and posterior tibialis pulses should both be palpated. Never assume that a decreased pulse is normal and the result of spasm. Ankle brachial indices are assessed and a decrease of 0.15 or greater indicates a significant vascular injury.16 The importance of early recognition of vascular injury cannot be overstated because a missed or delayed diagnosis may result in a below-knee amputation if the leg is not reperfused within 6 to 8 hours.
All patients with a normal vascular examination must have serial pulse examinations or undergo arteriography because intimal tears may be present. Intimal tears of the artery may present in a delayed fashion and are more difficult to diagnose. The initial physical examination may be completely normal in a knee with an intimal tear. Intimal tears can lead to a gradual thrombosis, which may propagate to complete arterial occlusion.
The neurologic examination, particularly of the peroneal nerve, should be documented. The patient is asked to actively dorsi-flex the foot and to activate the extensor hallucis longus tendon. These specific tests assess the peroneal nerve function. Sensation in all the nerve distributions, as well as motor function of the tibial nerve should be examined. The incidence of nerve injury with knee dislocation is between 16% and 40%.17-19 The peroneal nerve is most commonly injured, but injuries to the tibial nerve have occurred.20 Injuries to the lateral corner and PLC of the knee place the peroneal nerve at increased risk because of its superficial location as it curves around the fibular head. Posterior dislocations have a high incidence of nerve injuries. The prognosis of peroneal nerve injuries is poor. Complete nerve injuries only recover about 50% of the time. Nerve injuries are generally followed conservatively for 3 months. Of these injuries, about one third will recover, one third will have minor deficits, and one third will have a complete palsy.19
A detailed examination of the knee ligaments is performed on the ACL, PCL, MCL, and posterolateral anatomic structures. Initial and postreduction radiographs require thorough evaluation to assess for periarticular fractures, direction of dislocation, and adequacy of reduction. Magnetic resonance imaging will provide detailed information about the ligaments, bone or sub-chondral bone, menisci, and articular cartilage.21 The physical
Box 46-1 Pearls
1. In most cases, the history itself will lead the examiner to the correct diagnosis.
2. Always examine the uninjured knee for a comparison.
3. The Lachman test should be performed in neutral rotation. External rotation may cause a false-positive result in a knee with a medial collateral ligament injury.
4. Laxity of the knee joint with varus or valgus stress in full extension is a sign of a multiligamentous injury.
examination must be correlated with the magnetic resonance imaging findings for preoperative planning.
The purpose of the physical examination is to obtain the correct diagnosis. A complete patient history must be combined with a thorough physical examination in order to direct treatment of the knee injury. Additional tests such as radiographs, magnetic resonance imaging, bone scans, and angiography are sometimes used to provide information in the evaluation of a knee injury. The initial diagnosis of a knee dislocation or multiple-ligament knee injury is an orthopedic emergency. A vascular injury must be assumed until it can be ruled out. After the vascular status has been addressed, radiographs followed by a magnetic resonance imaging scan should be obtained. A complete ligament examination will help correlate the magnetic resonance imaging findings, and a preoperative plan can be established (Boxes 461 and 46-2).
1. Failure to examine the hip and spine in conjunction with the knee can result in a misdiagnosis (e.g., knee pain in a young adolescent can be the result of a slipped capital femoral epiphysis at the hip).
2. Do not assume that all knee swelling is an effusion.
3. A missed posterolateral corner injury is a common cause of anterior cruciate ligament reconstruction failure.
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8. Covey DC: Injuries of the posterolateral corner of the knee. J Bone Joint Surg Am 2001;83:106-118.
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10. Eren OT: The accuracy of joint line tenderness by physical examination in the diagnosis of meniscus tears. Arthroscopy 2003; 19:850854.
11. Wascher DC: High-velocity knee dislocation with vascular injury treatment principles. Clin Sports Med 2000;19:457-477.
12. Shelbourne KD, Porter DA, Clingman JA, et al: Low velocity knee dislocation. Orthop Rev 1991;20:995-1004.
13. Quinlan A: Irreducible posterolateral dislocation of the knee with button-holing of the medial femoral condyle. J Bone Joint Surg Am 1966;48:1619-1621.
14. Cole BJ, Harner CD: The multi-ligament injured knee. Clin Sports Med 1999;18:241-262.
15. Green NE, Allen BL: Vascular injuries associated with dislocation of the knee. J Bone Joint Surg Am 1977;59:236-239.
16. Kendall RW Taylor DC, Salvain AJ, et al: The role of arteriography in assessing vascular injuries associated with dislocations of the knee. J Trauma 1993;35:875-878.
17. Kennedy J: Complete dislocation of the knee joint. J Bone Joint Surg (Am) 1963;45:889-904.
18. Taft TW Almenkinders LC: The dislocated knee. In Fu F (ed): Knee Surgery. Baltimore, Williams and Wilkins, 1994, pp 837-857.
19. Borden PS, Johnson DL: Initial assessment of the acute and chronic multiple-ligament injured knee. Sports Med Arthrosc Rev 2001;9: 178-184.
20. Welling R, Kakkasseril J, Cranley J: Complete dislocations of the knee with popliteal vascular injury. J Trauma 1981;21:450-453.
21. Wilson TC, Johnson DL: Initial evaluation of the multiple-ligament injured knee. Oper Tech Sports Med 2003;11:187-192.
Principles of Knee Arthroscopy
William P Urban
• Knee arthroscopy is the most common procedure in orthopedic surgery.
• Originally developed as a diagnostic tool, the ability to directly visualize anatomic structures within the knee joint allows surgeons to perform intra-articular surgery through minimal incisions.
• While improvements in modern-day magnetic resonance imaging has decreased its usefulness as a diagnostic tool, advances in arthroscopic equipment and techniques have led to an increase in the number and complexity of arthroscopic procedures (Table 47-1).
• Current indications include the treatment of meniscal pathology, articular lesions, loose or foreign bodies, cruciate ligament reconstruction, patella malalignment, and intra-articular fractures. More than 600,000 knee arthroscopies are performed annually.1
Knee arthroscopy requires the use of basic instrumentation for all procedures. The arthroscope is a small telescopic device that is used to visualize structures within the knee joint. While a 30-degree arthroscope is typical, a 70-degree scope is sometimes used. The remainder of the video capture equipment includes a light source, camera head, and video system. Pictures can be saved as video or computer files or printed to paper depending on the equipment. A motorized shaver system and handheld instruments are the basic implements for performing surgery, although a wide array of equipment has been developed for specific procedures. Electrothermal devices or lasers should be considered an adjunct to the basic shaver and handheld instruments.
Knee arthroscopy is performed in a fluid environment using saline. A fluid management system or infusion pump is used to maintain fluid in the joint, distend the capsule, and lavage blood or other fluids that may obscure visualization. Current systems allow the surgeon to maintain a selected intra-articular pressure and flow rate.
Arthroscopic surgery can be performed under local, regional, or general anesthesia. Factors to be considered include the length of the procedure, tourniquet use, and postoperative pain control as well as patient and surgeon preference. Local anesthesia has become more popular with the increasing use of ambulatory surgery centers. Local anesthesia is typically used for simple cases with limited operative time. Local anesthesia is a poor choice for cases requiring additional portals or incisions. Since local anesthesia will be inadequate in 1% to 15% of cases,2 monitored anesthesia care can be used to provide supplemental sedation in order to increase patient acceptance. An intra-articular anesthetic with epinephrine should be injected 20 minutes before surgery3 to maximize analgesia and decrease bleeding. The skin and portals are injected prior to the incision. The use of a long-lasting anesthetic should be considered for postoperative pain control.
When additional portals or incisions are used, and hemosta-sis using a tourniquet is desired, regional anesthesia should be considered. Regional anesthesia, such as spinal or epidural blocks using a combination of analgesics and fentanyl, also allows manipulation and stressing of the knee to improve visualization and access to intra-articular structures. Spinal and epidural regional blocks can also be used for postoperative pain control through the use of a long-acting anesthetic or patient-controlled analgesia. Peripheral nerve blocks can be used to increase analgesia in conjunction with local anesthesia, to decrease anesthesia requirements with general anesthetics, or as a method of postoperative pain control.
General anesthesia is typically reserved for cases in which regional or local anesthesia would be inappropriate or con-traindicated. Examples include long, complicated cases that require complete relaxation, cases involving infection or coagu-lopathy, and cases in which the patient is unable or unwilling to remain awake during surgery.
The surgical sight should be marked by the surgeon before leaving the holding area in compliance with current patient safety protocols.4 Patients are given preoperative antibiotics 20 minutes before surgery using a broad-spectrum antibiotic covering Staphylococcus and Streptococcus organisms. This protocol can be modified when specific antibiotic coverage is needed for a known or suspected organism. Before positioning, an examination under anesthesia is performed. This examination, when the patient is pain free and relaxed (if under general anesthesia), is used to corroborate preoperative planning, the office examination, and radiographic studies. The repetitive performance of an examination under anesthesia before all surgical cases to deduce subtle findings is also an important technique for the
Table 47-1 Arthroscopic Procedure
Removal of loose/foreign body Plica resection/débridement Synovectomy Chondroplasty
Lysis of adhesions
Lateral release/capsular imbrication
Arthroscopically assisted fracture open reduction/internal fixation Osteochondral autograft transplantation beginning arthroscopist to hone his or her physical examination skills.
The patient is placed supine on a standard operating table with a tourniquet placed around the thigh. A wide, well-padded tourniquet should be used to decrease neurologic complications. The tourniquet should be kept as proximal as possible on the thigh to avoid the possibility of encroaching on the operative site. The decision to use a tourniquet is based on the operative procedure and surgeon's preference. New fluid management systems and high-flow cannulas, which control knee pressure and flow, make the performance of basic arthroscopic procedures without a tourniquet possible. Studies have shown that the use of a tourniquet increases postoperative quadriceps inhi-bition,5 and the surgeon should weigh this against the benefits of using a tourniquet, primarily decreased bleeding, and faster operative time. Procedures requiring additional incisions and bony work should entail the use of a tourniquet. Regardless, a tourniquet is applied in case its unexpected use is necessitated.
The foot of the table is dropped, and the operative leg is typically placed in an arthroscopic leg holder (Fig. 47-1). A leg holder allows the knee joint to be stressed and manipulated in order to help visualize the intra-articular compartments. Alternatively, a lateral post can be used to provide a valgus stress and the leg can be brought into a figure-four position to provide a varus stress. The nonoperative leg is placed in a leg holder to move it out of the way, allowing adequate access to the surgical extremity. With the increasing complexity of modern arthro-scopic procedures resulting in increasing operative times, ensuring that the well-leg holder is appropriately padded to avoid abnormal pressure that could result in compartment syndrome or neurologic injury is critical.
Anatomic landmarks and incision sights should be clearly marked out before starting the case (Fig. 47-2). The use of standard landmarks that can be used consistently for most arthro-scopic knee cases improves efficiency and prevents the need for determining new landmarks during unforeseen circumstances, after the knee has been distended and the anatomy altered. Standard landmarks should include the inferior pole of the patella, the medial and lateral edges of the patellar tendon, and the tibial tubercle. The medial and lateral joint line should also be marked in case posterior portals are required.
The anterolateral and anteromedial portals are then marked. The anterolateral portal is created just below the level of the inferior pole of the patella, approximately 1 cm above the joint line. The incision is placed just lateral to the patellar tendon. While the center of the "soft spot" more laterally has been advocated, this position makes accessing the posterior notch and the posterior compartment difficult in patients with a large Q angle.
The anteromedial portal is considered the working portal for arthroscopic surgery. This portal is approximately 5 mm lower than the lateral portal or 5 mm superior to the joint line. Again, the placement of this portal close to the patellar tendon allows access to the back of the notch and posterior compartments.
Some fluid management systems require the use of a super-omedial or superolateral portal. These portals are also used to remove loose/foreign bodies from the retinacular gutters or to provide direct access to the opposite side of the patellofemoral joint when a lateral release, capsular plication, or patellar microfracture is performed. The superolateral and superomedial patella portals are best created intraoperatively under direct visualization using a spinal needle for localization. Similarly when access to the posterior compartment is required, the posterior portals are created intraoperatively using the previously marked joint lines and transillumination with the arthroscope.
A transpatellar portal through the patella tendon has also been described, but because of concerns involving the violation of the extensor mechanism, it is rarely used. During the case, new portals can be easily created along the previously marked-out joint line if specific structures need to be accessed. Using transillumination, the joint line is confirmed and then palpated under arthroscopic visualization. Once the best position is determined, a spinal needle is simply placed through the skin. If the surgeon is satisfied with the position, a small stab incision is created using a no. 11 blade. The use of additional portals is preferable to struggling with poor access during the surgery or causing iatrogenic injury by forcing the instruments.
After the patient is positioned and prepped, the anterolateral portal is established. Using a no. 11 blade, a vertical incision directed into the notch is made through the skin large enough to accommodate the arthroscope. The incision is then carried down through the capsular tissue with the blade facing up to avoid accidentally cutting the meniscus. The capsule and underlying fat pad should be cut by dropping the hand, lowering the handle, and raising the cutting edge of the blade. This results in a funnel-shaped portal, wider in the joint than superficially. This geometry allows the scope to be more easily passed around the joint than with a simple stab incision (Fig. 47-3). The stab inci-
sion results in a tunnel-shaped incision in which the fat pad and retinacular tissue can hinder movement of the scope or, if wide enough, allows fluid to leak out around the arthroscope. Care should be taken not to overextend the skin incision as this will lead to flow from the portal during the procedure. If this does occur, a surgical sponge is simply hung around the scope at the level of the incision to redirect the leaking fluid into the arthroscopy bag.
Using a blunt obturator, the arthroscopic cannula is then inserted directly into the notch with the knee hanging in a flexed position. The scope should enter easily, and if resistance is encountered, the cannula should be removed and the capsular incision lengthened. The cannula is then passed behind the patellar tendon into the space anterior to the medial meniscus to ensure that it has completely passed through the fat pad and ligamentum mucosa, which attaches the fat pad to the intercondylar notch (Fig. 47-4). The knee is then brought into full extension, and the scope is directed under the patella into the suprapatellar pouch. The cannula should slip easily into the patellofemoral joint. If difficulty is encountered directing the scope superiorly, the capsular incision should be extended. The obturator is then removed, and the knee is copiously irrigated until clear in order to avoid delays caused by poor visualization. Only then is a 30-degree arthroscope inserted through the cannula. With the arthroscope inserted at a medial angle into the joint through the lateral portal, the lens should be directed laterally. The combined vectors result in a view, which is approximately straightforward (Fig. 47-5). This should be considered the standard arthroscopic position. Manipulation of the arthroscope around the joint requires smooth, mildly arcing motions because of the angle of the lens. Beginning arthroscopists mistakenly push or pull the scope straight back or forward when intending to move anteriorly or posteriorly in the knee joint.
Once in the suprapatellar pouch, the patella and trochlea should be inspected for any changes. The location and degree of any articular cartilage damage should be consistently graded should the operative report need to be reviewed without access to the intraoperative pictures. The knee should be flexed 45 degrees
to visualize the capture of the patella into the trochlear grove (Fig. 47-6). Subluxation and tilt of the patella should be noted. While the importance of a patella that is not anatomically situated in the groove at 45 degrees of flexion during arthroscopy has been debated,6 the technique provides general information that should be considered in conjunction with the physical examination, radiographic studies, and clinical history.
With the knee extended, the arthroscope should be directed superiorly and laterally into the lateral gutter, which is inspected for loose bodies or synovial plica. The lens should be rotated downward to visualize the gutter. The arthroscope is then directed medially into the medial gutter to visualize any loose
bodies. As the knee is brought into flexion, the lens is rotated medially and inferiorly to check for plica and any resulting damage to the femoral condyle (Fig. 47-7). As the scope continues around the curve of the condyle, the meniscocapsular junction will come into view. At this point, a valgus stress is applied to open up the medial compartment, and the arthro-scope is directed into the medial compartment.
With the arthroscope in the standard position, the medial compartment is assessed for chondral and meniscal pathology (Fig. 47-8). The posterior horn should be visible, and the lens is then rotated downward to view the anterior horn as it runs off the
anterior tibial plateau. With the lens again facing laterally, the arthroscope is directed into the intercondylar notch.
Unless obscured by the ligamentum mucosum, the anterior cruciate ligament should be visible. If the ligamentum mucosum prevents the scope from being directed laterally, the tip of the arthroscope should be brought superiorly, tracing the outline of the notch. The scope is then directed downward along the lateral margin, posterior to the fat pad, to visualize the cruciate ligaments. If the ligamentum remains a hindrance, a medial portal should be established and the ligamentum resected with a shaver. A no. 11 blade is used to create a stab incision at the previously marked location. The blade can be visualized with the arthroscope as it is directed into the notch. The blade is removed, and the blunt obturator is inserted through the portal into the notch.
After the anterior cruciate ligament is visualized, a probe should be inserted into the medial portal (Fig. 47-9). The tension on the anterior cruciate ligament should be assessed with a probe, and it should be visualized as an anterior drawer is performed. The posterior cruciate ligament in most knees will not be visualized, but its synovial covering is apparent. The arthro-scope is then brought to the anterior medial corner of the lateral plateau with the knee in flexion. With the arthroscope held in this location, a varus stress is created by bringing the leg into a figure-four position. As the compartment is distracted, the arthroscope is directed into the lateral compartment.
The articular cartilage and the meniscus are assessed and noted (Fig. 47-10). The lens should be rotated in order to give a complete view of the meniscus starting with the posterior horn. As the meniscus is examined, the popliteus tendon should be visible as it travels through the hiatus in the posterior horn of the lateral meniscus. As the lens is rotated downward and then medially around the anterior periphery, the anterior horn is visualized anterior to the lateral tibial spine, which separates it from the posterior horn.
Occasionally, the posterior compartment must be inspected. In order to visualize the posterior compartment, the scope is brought anteriorly along the joint line of the medial compartment with the knee in flexion. The camera is removed and replaced with the blunt obturator. The cannula is swept laterally across the anterior joint line by moving the base of the scope medially. The tip of the cannula remains in contact with the joint line until it falls into the notch. Remaining in contact with the lateral aspect of the medial condyle, the arthroscope is advanced posteromedially. As it is directed between the anterior cruciate ligament and the lateral aspect of the medial femoral condyle, tension will be felt as it passes the posterior cruciate ligament. As this occurs, the handle of the cannula is raised and it is advanced posteriorly and inferiorly. A sudden release in tension is felt as the obturator passes the posterior cruciate ligament and enters the compartment. The obturator is then removed and the 30-degree scope is reinserted. In order to visualize the posterior aspect of the posterior horn of the medial meniscus and the posterior joint line, a 70-degree arthroscope should be introduced. The wedging of the arthroscope between the wall of the notch and the cruciate ligaments makes moving the arthroscope difficult. The compartment is visualized by rotating the 70-degree lens. The reverse techniques can be used to reposition the scope into the lateral notch, viewing the posterior aspect of the lateral joint.
In certain cases, such as posterior cruciate ligament reconstruction, a posterior working portal is necessary. The postero-medial portal places the saphenous nerve at risk, while the posterolateral portal places the peroneal nerve at risk. To avoid possible neurovascular complications, the arthroscope in the posterior compartment is used to transilluminate the posterior joint line. Palpation is used to verify the placement, and a spinal needle is inserted into the joint under arthroscopic visualization. A superficial skin incision is then created, and the tissues are bluntly dissected down to the capsule using a clamp. The capsule is then incised, and a cannula is placed into the joint to avoid having to reestablish the portal every time an instrument is removed.
During diagnostic arthroscopy, a probe should be used through the medial portal to test the stability and consistency of any abnormal structures. As pathology is encountered, it should be addressed using instruments through the working portals. Inserting an appropriate arthroscopic grasper through the medial portal can be used to perform the simple removal of loose or foreign bodies. If there is difficulty holding the fragment, a spinal needle inserted into the knee joint through the capsule can pin the fragment in place to allow the surgeon to grasp it without the fragment slipping away. Objects located in the gutters, suprapatellar pouch, or posterior compartment may require the use of the superior patellar or posterior portals.
Soft-tissue pathology requiring resection can usually be accomplished using an arthroscopic biter or the motorized shaver. Shavers are usually available in 3.5-, 4.5-, or 5.5-mm diameters. Care should be taken to avoid using a large shaver in a small space where it will damage normal structures. The shaver blade rotates forward or reverse or oscillates based on the settings. The speed can also be controlled, with higher speeds being used to resect bone.
Typically, for plica resection or arthroscopic meniscectomy, a full radius shaver is used. Other shavers can be used based on the surgeon's preference and experience. Soft-tissue resection should be performed with the shaver on oscillate. Suction is used to draw the tissue into the shaver. Bony resection is commonly performed with the shaver on forward or reverse rather than oscillate. While a full-radius shaver can be used, depending on the size of the resection and bone quality, burrs and specialized bone shavers are sometimes utilized.
After the procedure is completed, the knee should be irrigated and drained of fluid. The skin portals may be closed with subcutaneo
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