V

Unlock Your Hip Flexors

Unlock Your Hip Flexors

Get Instant Access

50

Graft Choices in Ligament Surgery

Andrew D. Pearle and Answorth A. Allen

In This Chapter

Biology and biomechanics Autografts

Bone-patellar tendon-bone (BPTB) Hamstring tendon Quadriceps tendon Allografts

Different patient characteristics dictate certain grafts. These include lifestyle (such as job and religion), sports activity, age, and pre-existing comorbidities such as previous hamstring injuries as well as patellofemoral issues such as chondrosis/ arthrosis, instability, previous trauma, and Osgood-Schlatter disease. In addition, surgeon comfort level with specific grafts and techniques affects decision making.

The purpose of this chapter is to introduce the biology, bio-mechanics, fixation strategies, risks, pitfalls, and outcomes of the common graft choices in ligament surgery. Basic understanding of these issues helps guide appropriate matching of graft to patient.

BASIC BIOLOGY AND BIOMECHANICS OF GRAFTS IN LIGAMENT SURGERY

Current rehabilitation protocols for knee ligament reconstruction stress immediate range of motion, return of neuromuscular function, proprioception, and early weight bearing up the kinetic chain. It is therefore essential to understand the biology and time course of graft remodeling and incorporation into the bone.

The biology of healing of the ligament replacement graft is grossly the same for all biologic graft materials. Tendon grafts go through biologic stages during the process of "ligamentization." First, the graft undergoes inflammation and necrosis. Early inflammation and neovascular proliferation is seen within the first couple of weeks after graft reconstruction. The graft then undergoes revascularization and repopulation with fibroblasts over the ensuing 4 to 8 weeks. During this stage, all the donor fibroblasts undergo cell death, but the collagen structure of the tendon serves as a scaffold for extrinsic fibroblast ingrowth. This complete repopulation of the graft with host fibroblasts is thought to occur both in autografts and allografts. The final stage involves a gradual remodeling of the graft and the collagenous structure. The rate and predictability of ligamentization vary among autograft and allograft tissues and are discussed later in the chapter.

The initial strength, stiffness, and cross-sectional areas of various ligament grafts is well characterized and summarized in Table 50-1. While these initial biomechanical properties are important determinants of graft suitability, grafts undergo a long evolution of incorporation and their structural properties are dramatically altered over time. All biologic grafts lose their initial strength during the early healing period,1-3 and in animal models, only 10% to 50% of native anterior cruciate ligament (ACL) stiffness and strength is restored at 3 years after graft reconstruction.4,5

Grafts are thought to weaken during the ligamentization process because the repopulation of biologic grafts with intrinsic fibroblasts is accompanied by partial breakdown of the extracellular matrix of the graft and replacement with scarlike tissue.6 Animal studies have demonstrated that the graft is at its weakest 3 months after surgery. This evolutionary process of graft remodeling must be understood in coordinating postoperative rehabilitation strategies.

In the early postoperative period, the main factor affecting the structural strength of the graft is not the tensile strength of the graft tissue, but the fixation of the graft to the bone.7 Graft fixation is the "weak link" in this period as no graft fixation devices have achieved the ultimate failure strength or stiffness comparable to the native ACL. The best fixation constructs achieve pull-out strength that is almost 50% of the initial tensile strength of the graft.8-10 The tensile load to failure of various fixation devices is shown in Table 50-2. This weak link of the graft fixation persists for up to 4 to 12 weeks; at that point, attachments to the bone are probably no longer the weakest part of the complex.

Current fixation techniques include aperture fixation strategies in which the soft tissue or bone of the graft is fixed within the bone tunnel and suspensory or periosteal fixation in which

INTRODUCTION

• Graft choice in knee ligament surgery remains a notoriously controversial topic among sports medicine orthopedists.

• Numerous graft choices are available and studies are available to support a high rate of "good" to "excellent" results with each graft type.

• The perfect graft would have no donor site morbidity, reproduce the mechanical properties of the native ligament, provide biologic insertional incorporation, and supply neuromuscular control.

• While the perfect graft does not exist, the available choices each have pros and cons that can be tailored to the specific patient needs.

Table 50-1 Initial Biomechanical Properties of Various Autograft Choices

Graft

Ultimate Strength (N)

Stiffness (N/mm)

Cross-sectional Area

(mm2)

Intact ACL

2160

242

44

BPTB (10 mm)

2977

620

50

Quadruple hamstring

4590

861

53

Quadriceps tendon (10 mm)

2352

463

62

ACL, Anterior cruciate ligament; BPTB, bone-patellar tendon-bone. Fu FH, Bennett CH, Lattermann C, et al: Current trends in anterior cruciate ligament reconstruction. Part 1: Biology and biomechanics of reconstruction. Am J Sports Med 1999;27:821-830.

ACL, Anterior cruciate ligament; BPTB, bone-patellar tendon-bone. Fu FH, Bennett CH, Lattermann C, et al: Current trends in anterior cruciate ligament reconstruction. Part 1: Biology and biomechanics of reconstruction. Am J Sports Med 1999;27:821-830.

the graft is fixed away from the joint surface (Fig. 50-1). Different fixation techniques have different biologic consequences. While no current fixation device reliably promotes complete recapitulation of the normal biology of the transition zones at the insertion of the ACL or posterior cruciate ligament (PCL), certain principles of fixation are generally recognized. There is increased knee stability with interference aperture fixation placed close to the joint. Periosteal fixation, especially with the use of indirect tendon fixation devices that rely on linkage material such as suture to connect the graft to the fixation device, are associated with the "bungee effect." This longitudinal graft micromotion along the axis of the osseous tunnel is thought to contribute to tunnel widening. Indirect fixation devices may also allow the graft to move anteriorly and posteriorly within the osseous tunnel during flexion and extension. This sagittal graft motion is termed the "windshield wiper effect." Fixation tech-

Table 50-2 Ultimate Tensile Load of Various Fixation Devices

Type of Fixation Device

Ultimate Tensile Load (N)

Indirect

Single polyester tape loop

375

Double polyester tape loop

612-651

Single loop 5 Ethibond

238

Double loop 5 Ethibond

463

Direct Soft Tissue

Metal interference screw (7 mm)

242

Bioabsorbable screw (7 mm)

341

Cross-pin technique (animal)

725-1600

Suture-post (animal)

374

Direct Bone

Metal interference screw (7 mm)

640

Metal interference screw (9 mm)

276-436

Experiments performed on human cadavers, unless otherwise specified. Fu FH, Bennett CH, Lattermann C, et al: Current trends in anterior cruciate ligament reconstruction. Part 1: Biology and biomechanics of reconstruction. Am J Sports Med 1999;27:821-830.

Experiments performed on human cadavers, unless otherwise specified. Fu FH, Bennett CH, Lattermann C, et al: Current trends in anterior cruciate ligament reconstruction. Part 1: Biology and biomechanics of reconstruction. Am J Sports Med 1999;27:821-830.

niques continue to evolve but are beholden on the type of graft used.

A summary of the essential criteria for comparisons of different grafts is listed in Table 50-3. Specific characteristics of the biology and biomechanical properties as well as other criteria essential for appropriate graft decision making, are explored for common types of knee ligament grafts in the remainder of the chapter.

AUTOGRAFTS

Bone-Patellar Tendon-Bone Autografts

The central third bone-patellar tendon-bone autograft has been the gold standard graft choice since it was popularized in the 1980s. Graft harvest is performed with the knee held in 90 degrees of flexion; the patella and tendon are exposed by subcutaneous dissection. A straight midline incision is made through the peritenon, which is then carefully preserved and dissected off the tendon both medially and laterally. Though the width of the graft is customized to the individual patient, typically a 10 mm wide graft from the central third of the patella tendon is used. The longitudinal strip of the central patella is harvested along with 20- to 25-mm bone plugs from the tibial tubercle and patella (Fig. 50-2).

The BPTB autograft has high tensile strength and stiffness as well as strong bony insertion points. A 10-mm patellar tendon graft has been shown to have an initial ultimate tensile load and stiffness that is higher than that of the native ACL (2977 N versus 2160 N and 455 N/mm versus 242 N/mm, respectively).11 As mentioned, this strength and stiffness of the graft tissue is a dynamic property that undergoes predictable changes during ligamentization. While the initial soft-tissue characteristics are favorable compared to native tissue, the ultimate load to failure of the patellar tendon autograft has been shown to decrease over time and stabilizes at approximately 80% of its initial strength at 12 months.12

Apart from its favorable initial biomechanical properties, the most compelling advantage of BPTB autograft is the presence of the bone plug on each end of the tendon (Fig. 50-3). The native bone-tendon interface is harvested in its entirety. This obviates the issue of soft-tissue tendon-to-bone healing, which is problematic in other graft choices. In the BPTB autograft, the bone plug of the graft is fixed directly to the bone in the tunnel, ensuring bone-to-bone healing. This healing is thought to be more rapid than soft tissue-to-bone healing as appositional integration of the graft bone into the host has been demonstrated at 3 to 4 weeks after surgery in a dog model.13

Fixation of bone plugs is traditionally the most reliable and predictable type of graft fixation. The bone plugs themselves can provide an interference fit within the tunnel. Mechanical locking of the bone plugs with an interference screw provides rigid fixation that allows for early, aggressive rehabilitation. The ability to achieve aperture fixation with bone-to-bone healing is thought to prevent longitudinal graft motion in the tunnel.

A significant disadvantage of the BPTB autograft is donor site morbidity. Meticulous surgical technique is required to prevent intraoperative complications at the donor site such as patellar fracture and damage to the infrapatellar branch of the saphe-nous nerve. Major postoperative complications such as patellar tendon rupture and delayed patellar fracture are rare, but do occur.

Although major intraoperative or postoperative complications at the donor site are uncommon, there is ongoing concern about

Acl Bptb Surgery FixationQuadripal Semi Graft

Figure 50-1 A, Aperture fixation with interference screws is the most common fixation strategy for grafts that incorporate bone plugs. Aperture fixation minimizes micromotion of the graft within the tunnel. B, Periosteal or suspensory fixation involves fixing the graft to posts or buttons outside the tunnel. With indirect periosteal fixation, as pictured here, linkage material such as suture is used to connect the graft to the fixation device. These types of fixation devices are often used in soft-tissue grafts without bone plugs and are thought to allow longitudinal micromotion in the tunnel (the "bungee effect").

Table 50-3 Criteria to Compare Graft Choices

Table 50-3 Criteria to Compare Graft Choices

Acl Plug Graft
Harner CD: Anterior Cruciate Ligament Graft Selection in 2005. Paper presented at the American Academy of Orthopaedic Surgeons 72nd Annual Meeting, 2005, Washington, DC.
Ligamentization Acl Graft

Figure 50-2 A, Bone-patellar tendon-bone (BPTB) harvest: The central third of the patellar tendon is harvested with bone plugs from the patella and tibia. B, Bone-patellar tendon-bone graft prepared for an anterior cruciate ligament (ACL) procedure (left) and arthroscopic picture after BPTB ACL reconstruction (right).

Figure 50-2 A, Bone-patellar tendon-bone (BPTB) harvest: The central third of the patellar tendon is harvested with bone plugs from the patella and tibia. B, Bone-patellar tendon-bone graft prepared for an anterior cruciate ligament (ACL) procedure (left) and arthroscopic picture after BPTB ACL reconstruction (right).

Patellofemoral Ligament Repair Procedure
Figure 50-3 Arthroscopic picture after hamstring graft anterior cruciate ligament reconstruction.

permanent changes to the extensor mechanism resulting in altered patellofemoral biomechanics. Common long-term sequelae that have been reported after BPTB harvest include loss of quadriceps strength, patellofemoral crepitation, anterior knee pain, loss of flexion, and pain when kneeling.14-16 Many of these reported sequelae are based on retrospective studies that lack comparison groups. For example, while anterior knee pain has been reported to occur in 10% to 40% of patients after BPTB autograft harvest, it is increasingly clear that anterior knee pain may occur after ACL reconstruction regardless of graft choice.17 Bynum et al18 showed that up to 40% of patients with ACL rupture will have anterior knee pain prior to their operation, suggesting that the etiology of anterior knee pain associated with ACL injury and reconstruction is multifactorial. Many reports of quadriceps atrophy after BPTB autograft harvest predate the accelerated rehabilitation programs used currently; therefore, implicating the graft type as the primary etiology of the quadriceps weakness is problematic.

Pain with kneeling, on the other hand, is supported by consistent data from randomized, controlled studies comparing

BPTB grafts to hamstring grafts.17 This pain is usually mild and its affect on patient-relevant outcomes is unknown. For patients who are required to kneel for prolonged periods, BPTB autografts are probably not a good graft choice.

Multiple studies have demonstrated long-term stability after BPTB ACL reconstruction approaching 95%.14-16,19,20 Proponents of this graft point to its rigid fixation constructs, predictable bone-to-bone healing, robust initial graft strength, and reliable and durable stability. It remains the most common graft used in professional athletes. Relative contraindications to BPTB auto-graft include patellofemoral arthritis, advanced age, and previous patellar tendon graft harvest.

Hamstring Tendon

There is a long history of successful clinical outcomes following knee ligament reconstruction using hamstring grafts.21-25 However, concerns remain regarding the recurrence of atrau-matic knee laxity, gender differences, fixation strategies, bone tunnel widening, residual hamstring weakness, and the suitability of hamstring grafts for certain athletic activities. Hamstring graft constructs continue to evolve, and it is difficult to compare results of historic studies due to variations in the reported surgical techniques. While initial hamstring grafts consisted of a single- or double-strand hamstring graft, at present, the most common type of hamstring graft is the quadrupled semitendi-nosus and gracilis graft.22,26,27 This graft is a semitendinosus tendon and gracilis tendon doubled, or folded over, to produce four strands in the final construct.

Hamstring grafts are harvested through a small incision performed at the level of the pes anserinus. Dissection is taken down to the level of the sartorius fascia, which is incised. The semitendinosus and gracilis tendons are identified, freed from fascial attachments, and harvested using a tendon stripper. Meticulous care is used to free the tendon of all attachments so as to prevent transection of the tendon with the stripper. Once harvested, residual muscle is carefully dissected off the tendons and they are folded over one of a myriad of fixation devices to produce a quadruple-strand graft.

The quadruple hamstring graft has the highest initial ultimate strength and stiffness of any of the commonly used grafts.28 However, this value is from in vitro data after equal tensioning of all strands. Clinically, this uniform tensioning may be difficult to achieve, reducing the initial biomechanical properties of the graft. In addition to its high initial strength, the dimensionality of the quadruple hamstring is more akin to the native ACL as it is round and has a larger cross-sectional area than the BPTB auto-graft. This provides improved "fill" of the bone tunnels with graft material. Proponents of this graft also suggest that the multiple strands of the quadruple graft construct may recapitulate the distinct functional units of the two-band ACL structure.

In general, hamstring graft harvest results in less immediate postoperative pain and morbidity than are present after a BPTB autograft. Because the incision is away from the patella, patients rarely complain of discomfort while kneeling. In skeletally immature patients, hamstring grafts offer the advantage of soft-tissue apposition to the growth plate. Bone plugs at the end of BPTB autografts could theoretically bridge the physis leading to premature closure resulting in angular deformities or limb length discrepancies; hamstring ACL reconstruction in this patient population has been shown to have a low risk of growth disturbance.29

While these properties of hamstring grafts are compelling, there are distinct disadvantages of hamstring grafts compared to BPTB grafts. Fixation strategies for hamstring tendon graft have been problematic. In the past, fixation of hamstring tendons was performed by suturing the ends of the graft and fixing the sutures around posts placed outside the bone tunnels. Because of the elasticity of the sutures and the long length created by the entire graft and suture unit, there was concern about the "bungee effect" with micromotion of the graft in the tunnels. This is thought to interfere with healing of the graft soft tissue to the bone as well as resulting in graft tunnel widening.

Recently, new methods of hamstring graft fixation have evolved that provide aperture fixation and provide pull-out strength comparable with that of interference screw fixation for bone-tendon constructs. For example, soft-tissue interference screws, designed with blunt threads designed not to cut the hamstring tendons, provide aperture fixation of the tendon to the bone. These interference screws are available in biore-sorbable formulations and are available impregnated with hydroxyapatite with the theoretical advantage of improved bone ingrowth.

Regardless of the fixation strategy, hamstring grafts rely on soft tissue-to-bone healing, which is thought to be slower than bone-to-bone healing. In a rhesus monkey study, the bone-bone plug interface was histologically incorporated at 8 weeks after surgery, which was the first time point at which the histology was examined.30 In a dog model of soft tissue-to-bone healing, the soft-tissue tendon graft pulled out of the bone tunnel until 12 weeks postoperatively, indicating that incorporation of the soft tissue-to-bone interface was incomplete for as long as 3 months postoperatively.7 However, other animal studies have suggested more rapid soft tissue-to-bone healing.31

Clinically, hamstring grafts have a high incidence of tunnel widening, which is sometimes seen as early as 3 months after hamstring graft ACL reconstruction. The biology behind tunnel widening is unknown but may involve an inflammatory reaction at the soft tissue-bone interface indicative of areas of incomplete incorporation. There is concern that micromotion of the soft tissue within the bone tunnel may promote this process. Williams et al32 demonstrated that tunnel expansion was noted radiographically in all patients (n = 85) after hamstring ACL reconstruction using suspensory fixation for the femoral tunnel and periosteal fixation for the tibial tunnel. The clinical significance of tunnel widening is unclear as there is no direct correlation between tunnel widening and laxity.

Other disadvantages of hamstring grafts include unpredictable hamstring size, concerns about recurrent knee laxity, and hamstring weakness. While residual hamstring weakness is not drastic, it typically measures about 10% loss after recovery. This could be problematic for athletes who play a hamstring-specific sport such as running backward (e.g., a defensive back).

Comparison of Hamstring versus Bone-Patellar Tendon-Bone Autografts

A large number of studies have been published comparing hamstring and BPTB autografts expressing a myriad of different opinions. The majority of these studies are case series reporting on the use of a single graft, without an appropriate comparison group. In addition, with the evolution of graft preparation and fixation, particularly with hamstring grafts, it is difficult to use the studies to supervise graft choice decisions. In a recent metaanalysis of 34 studies involving 1976 patients, Freedman et al33 reported a graft failure rate of 4.9% in hamstring grafts and 1.9% in bone-patellar bone grafts. Significant laxity and presence of a pivot shift was slightly higher in the hamstring groups. Anterior knee pain was present in 17.4% of BPTB patients as compared to 11.5% of hamstring patients.

Spindler et al17 recently presented a systematic review of the nine randomized, controlled trials that compared patellar tendon and hamstring tendon autografts. A slight increased laxity (approximately 1 mm) on arthrometer testing was found in the hamstring population in three of seven studies. Knee pain with kneeling was greater for the patellar tendon population in four of four studies, but only one of nine studies demonstrated increased anterior knee pain in the patellar tendon group. There were no differences in subjective outcome, return to activity, or failure rates identified by the randomized studies. This review suggests that graft type is not the major determinant of successful outcome in ACL reconstruction when using either hamstring or patellar tendon autograft.17

Quadriceps Tendon

Quadriceps tendon autografts have gained attention for primary and revision knee ligament surgery.34-36 This graft is harvested by removing a strip of the distal portion of the quadriceps along with a block of bone from the proximal patella. This results in a graft that consists of a bone plug on one end for bone-on-bone fixation and tendon of the other end for soft tissue-to-bone fixation.

Quadriceps tendon grafts have a thicker cross-sectional area than patellar tendon grafts and roughly the same tensile strength.37 Proponents of this method suggest that postoperative pain with quadriceps tendon grafts is not as intense as with BPTB harvesting. Patients with quadriceps tendon grafts usually do not have symptoms of patellar tendonitis upon return to sports and often have minimal or no difficulty kneeling. In addition to its use in the primary setting, this graft is useful in the revision setting and can be harvested even after a previous BPTB graft.

Disadvantages of this graft include the same intraoperative and postoperative risks of patellar fracture as are seen with BPTB and a decrease of up to 20% of quadriceps strength.38 Because quadriceps tendon harvest is not widely used and unfamiliar to many surgeons, the harvesting technique, with its subtle anatomic nuances, remains a challenge when using this graft. For example, the proximal patella has a curved surface with dense cortical bone that closely adheres to the suprapatel-lar pouch. When harvesting the graft, there is significant risk of entering the suprapatellar pouch and losing knee distention during ACL reconstruction.34

ALLOGRAFTS

Harvested from cadaveric sources, bone and soft-tissue allografts have been used successfully for a variety of conditions. Advantages of allograft ligament reconstruction include the avoidance of donor site morbidity and additional scars, decreased operative time, ease in performing multiple ligament reconstruction, and the use of a larger possible graft (Fig. 50-4).

Certain scenarios are particularly attractive for allograft use. These include primary ACL reconstruction in the older patient; revision ACL reconstruction when previous autogenic sources have been used; PCL reconstruction, particularly in the setting of double bundle procedures; posterolateral corner reconstruction; multiple ligament reconstruction (ACL, PCL, lateral collateral ligament) and cases of patient preference (cosmesis, decreased postoperative pain). The most common types of allo-

Pcl Double Bundle
Figure 50-4 Achilles tendon allograft fashioned for anterior cruciate ligament reconstruction. The calcaneal bone plug has been contoured to fit within a 25 x 10-mm femoral tunnel. The tendinous end will be secured in the tibial tunnel.

grafts used as knee grafts include Achilles tendon, BPTB, and quadruple hamstring tendon.

Allografts are procured from donor cadavers after a detailed medical, social, and sexual history questionnaire is completed by the next of kin or life partner. Any history of exposure to communicable diseases, reports of unprotected sexual contacts, drug use, neurologic diseases, autoimmune disease, collagen disorders, or metabolic diseases is recorded, and positive findings disqualify the donor. Blood and laboratory tests are used to rule out bacterial and viral infection.

Allografts are processed using a variety of methods. Unfortunately, most methods that ensure complete sterility are unsuitable for human tissue. High doses of gamma irradiation (>3.0 mrad) are effective for sterilizing the tissue but cause structural weakening of the collagen. Lower dose irradiation does not reliably kill viruses. Chemical sterilization agents such as ethylene oxide leave behind a residue that can cause chronic synovitis.

Allografts are commonly preserved by deep freezing, cryo-preservation, or freeze-drying. Deep freezing is the most common method of storage and involves an antibiotic soak prior to packaging without solution and freezing to -80oC. It can then be stored for 3 to 5 years. This process destroys all the cells in the tissue and is thought to decrease the host immune response. Cryopreservation involves controlled-rate freezing with extraction of cellular water in an effort to preserve cellular viability. Freeze-drying involves a lyophilization process to ensure residual moisture of less than 5%; the graft can then be stored at room temperature for 3 to 5 years. The freeze-dried graft requires rehydration for 30 minutes prior to implantation. Freeze-drying destroys cells in the tissue and reduces the immunogenicity of the tissue, but the strength of the graft is altered by the process. The preferred processing method for knee ligament allograft surgery remains deep freezing.

A primary concern with the use of allograft is the risk of viral and bacterial disease transmission. Hepatitis and human immunodeficiency virus can be transmitted through these tissues and bacterial infections are also a possibility; Buck et al39 calculated the risk of human immunodeficiency virus transmission in properly screened and tested donors to be 1:1,600,000. A full review of the risk of disease transmission in allograft tissue is presented in Chapter 12, entitled "Safety Issues for Musculoskeletal Allografts."

Unlike organ transplants, allografts are at minimal risk of tissue rejection by the host due to the minimal protein antigen in the processed allografts. Collagen, the major constituent of the grafts, has minimal antigenicity, and frank rejection of an allograft ligament is rare. However, a low-grade immune response may occur; Harner et al40 demonstrated a mild humoral response to allograft ligament transplantation in a majority of patients at 6 months after surgery. The clinical significance of this type of immune response is unknown.

Like autografts, allografts are thought to function as a biologic scaffold and undergo cellular repopulation, revascularization, and collagen remodeling. Initial repopulation may proceed quickly, as replacement of the graft by host cells has been evident at 4 weeks postoperatively.41 However, the overall liga-mentization process is thought to proceed more slowly for allografts compared to autografts, presumably due to a prolonged remodeling phase. Animal studies have investigated the biome-chanical properties of allografts versus autografts after ligament reconstruction. In a goat model, Jackson et al42 demonstrated that allograft patellar tendon ACL reconstruction resulted in increased anteroposterior laxity, decreased ultimate tensile load, and diminished biologic incorporation compared to autograft at 6 months after surgery. However, Nikolaou et al43 demonstrated nearly identical ligament strength between ACL allograft and autograft reconstructions in a dog model at 9 months after surgery. It has been estimated that allograft incorporation takes up to 1.5 times as long as the incorporation of autograft tissue. Though the remodeling phase may be prolonged with allografts, once it is complete, allograft ligament tissue appears histologically and functionally similar to autograft tissue.

Comparative studies of allograft and autograft ACL reconstruction have failed to demonstrate consistent differences in objective or subjective outcomes.44-47 There remains some concern about long-term allograft function; however, there has been no clinical difference between allograft and autograft function at 3- and 5-year follow-up.44,45

SYNTHETIC GRAFTS

Synthetic grafts remain an appealing alternative to biologic grafts but have a long history of failure. The ideal synthetic graft would mimic the characteristics of a normal ACL graft in terms of strength, compliance, elasticity, and durability without side effects.

In the 1990s, Gore-Tex grafts (Gore and Co., Flagstaff, AZ) were used but failed dramatically. These grafts were knitted cable with eyelets on each end that allowed for fixation to the bone outside the tunnels. Repeated cycling led to fragmentation of the grafts with shedding of particulate debris that led to persistent effusions and graft failure. Dacron and carbon fiber grafts had a similar history of failure.

More recently, the Kennedy Ligament Augmentation Device (3M, St. Paul, MN) was used to supplement ACL grafts. The purpose of this device was to protect the graft reconstruction until healing occurred. Unfortunately, the ligament augmentation device was too stiff and shielded the graft from normal stresses, delaying maturation of the graft. These devices are no longer used for ACL reconstruction. Currently, there are no prosthetic ligaments in the United States approved by the U.S. Food and Drug Administration, although several are currently being used in Europe.

CONCLUSIONS

Graft selection in knee ligament surgery remains a contentious topic among orthopedic surgeons. No single graft has been shown to be clearly superior in terms of overall patient outcome. In choosing the appropriate graft for the individual patient, surgeons must be versed in each graft's biomechanical characteristics, fixation and incorporation properties, donor site morbidities, and contraindications. In addition, graft selection is mitigated by the surgeon's comfort level with the surgical techniques required for use of the grafts.

At our institution, BPTB grafts are routinely used for ACL reconstruction in young, competitive athletes. Hamstrings grafts are commonly used in patients with pre-existing patellofemoral abnormalities such as chondrosis or arthrosis and in patients whose job requires kneeling such as firefighters or wrestlers. Achilles tendon allografts are commonly used for revision ACL surgery, primary PCL reconstruction, and multiligament knee reconstruction. Increasingly, we are using Achilles tendon allografts for primary ACL reconstruction, particularly in patients older than 30 and in recreational athletes. We have found that matching individual patients with grafts that are tailored to their needs has resulted in more targeted and appropriate graft selection.

REFERENCES

1. Butler DL: Anterior cruciate ligament: Its normal response and replacement. J Orthop Res 1989;7:910-921.

2. Fu FH, Jackson DW, Jamison J, et al: Allograft reconstruction of the anterior cruciate ligament. In Jackson DW Arnoczky SP, Woo SL-Y, et al (eds): Anterior Cruciate Ligament. Current and Future Concepts. New York, Raven Press, 1993, pp 325-338.

3. McFarland EG, Morrey BF, An KN, et al: The relationship of vascular-ity and water content to tensile strength in a patellar tendon replacement of the anterior cruciate in dogs. Am J Sports Med 1986; 14: 436-448.

4. Ballock RT, Woo SL, Lyon RM, et al: Use of patellar tendon autograft for anterior cruciate ligament reconstruction in the rabbit: A long-term histologic and biomechanical study. J Orthop Res 1989;7:474-485.

5. Ng GY, Oakes BW Deacon OW et al: Biomechanics of patellar tendon autograft for reconstruction of the anterior cruciate ligament in the goat: Three-year study. J Orthop Res 1995;13:602-608.

6. Oakes BW: Collagen ultrastructure in the normal ACL and in ACL graft. In Jackson DW Arnoczky SP, Woo SL, et al (eds): Anterior Cruciate

Ligament. Current and Future Concepts, New York, Raven Press, 1993, pp 209-217.

7. Rodeo SA, Arnoczky SP, Torzilli PA, et al: Tendon-healing in a bone tunnel. A biomechanical and histological study in the dog. J Bone Joint Surg Am 1993;75:1795-1803.

8. Jomha NM, Raso VJ, Leung P: Effect of varying angles on the pullout strength of interference screw fixation. Arthroscopy 1993;9:580-583.

9. Kohn D, Rose C: Primary stability of interference screw fixation. Influence of screw diameter and insertion torque. Am J Sports Med 1994;22:334-338.

10. Matthews LS, Lawrence SJ, Yahiro MA, et al: Fixation strengths of patellar tendon-bone grafts. Arthroscopy 1993;9:76-81.

11. Cooper DE, Deng XH, Burstein AL, et al: The strength of the central third patellar tendon graft. A biomechanical study. Am J Sports Med 1993;21:818-824.

12. Johnson DL, Isbell WM, Atay OA: Grafts. In Miller MD, Cole BJ (eds): Textbook of Arthroscopy. Philadelphia, Saunders, 2004, pp 3945.

13. Yoshiya S, Nagano M, Kurosaka M, et al: Graft healing in the bone tunnel in anterior cruciate ligament reconstruction. Clin Orthop 2000;376:278-286.

14. Bach BR Jr, Levy ME, Bojchuk J, et al: Single-incision endoscopic anterior cruciate ligament reconstruction using patellar tendon autograft. Minimum two-year follow-up evaluation. Am J Sports Med 1998;26: 30-40.

15. Bach BR Jr, Tradonsky S, Bojchuk J, et al: Arthroscopically assisted anterior cruciate ligament reconstruction using patellar tendon autograft. Five- to nine-year follow-up evaluation. Am J Sports Med 1998;26: 20-29.

16. O'Brien SJ, Warren RF, Pavlov H, et al: Reconstruction of the chronically insufficient anterior cruciate ligament with the central third of the patellar ligament. J Bone Joint Surg Am 1991;73:278-286.

17. Spindler KP, Kuhn JE, Freedman KB, et al: Anterior cruciate ligament reconstruction autograft choice: Bone-tendon-bone versus hamstring: does it really matter? A systematic review. Am J Sports Med 2004;32:1986-1995.

18. Bynum EB, Barrack RL, Alexander AH: Open versus closed chain kinetic exercises after anterior cruciate ligament reconstruction. A prospective randomized study. Am J Sports Med 1995;23:401-406.

19. Buss DD, Warren RF, Wickiewicz TL, et al: Arthroscopically assisted reconstruction of the anterior cruciate ligament with use of autogenous patellar-ligament grafts. Results after twenty-four to forty-two months. J Bone Joint Surg Am 1993;75:1346-1355.

20. Shelbourne KD, Gray T: Anterior cruciate ligament reconstruction with autogenous patellar tendon graft followed by accelerated rehabilitation. A two- to nine-year followup. Am J Sports Med 1997;25:786-795.

21. Aglietti P, Buzzi R, Menchetti PM, et al: Arthroscopically assisted semi-tendinosus and gracilis tendon graft in reconstruction for acute anterior cruciate ligament injuries in athletes. Am J Sports Med 1996;24: 726-731.

22. Aglietti P, Buzzi R, Zaccherotti G, et al: Patellar tendon versus doubled semitendinosus and gracilis tendons for anterior cruciate ligament reconstruction. Am J Sports Med 1994;22:211-218.

23. Aglietti P, Giron F, Buzzi R, et al: Anterior cruciate ligament reconstruction: Bone-patellar tendon-bone compared with double semitendi-nosus and gracilis tendon grafts. A prospective, randomized clinical trial. J Bone Joint Surg Am 2004;86:2143-2155.

24. Barber FA: Tripled semitendinosus-cancellous bone anterior cruciate ligament reconstruction with bioscrew fixation. Arthroscopy 1999;15: 360-367.

25. Giron F, Aglietti P, Cuomo P, et al: Anterior cruciate ligament reconstruction with double-looped semitendinosus and gracilis tendon graft directly fixed to cortical bone: 5-year results. Knee Surg Sports Trau-matol Arthrosc 2005;13:81-91.

26. Maeda A, Shino K, Horibe S, et al: Anterior cruciate ligament reconstruction with multistranded autogenous semitendinosus tendon. Am J Sports Med 1996;24:504-509.

27. Wallace MP, Howell SM, Hull ML: In vivo tensile behavior of a four-bundle hamstring graft as a replacement for the anterior cruciate ligament. J Orthop Res 1997;15:539-545.

28. Hamner DL, Brown CH Jr, Steiner ME, et al: Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechanical evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg Am 1999;81:549-557.

29. Marder RA, Raskind JR, Carroll M: Prospective evaluation of arthro-scopically assisted anterior cruciate ligament reconstruction. Patellar tendon versus semitendinosus and gracilis tendons. Am J Sports Med 1991;19:478-484.

30. Clancy WG Jr, Narechania RG, Rosenberg TD, et al: Anterior and posterior cruciate ligament reconstruction in rhesus monkeys. J Bone Joint Surg Am 1981;63:1270-1284.

31. Grana WA, Egle DM, Mahnken R, et al: An analysis of autograft fixation after anterior cruciate ligament reconstruction in a rabbit model. Am J Sports Med 1994;22:344-351.

32. Williams RJ 3rd, Hyman J, Petrigliano F, et al: Anterior cruciate ligament reconstruction with a four-strand hamstring tendon autograft. J Bone Joint Surg Am 2004;86:225-232.

33. Freedman KB, D'Amato MJ, Nedeff DD, et al: Arthroscopic anterior cruciate ligament reconstruction: A metaanalysis comparing patellar tendon and hamstring tendon autografts. Am J Sports Med 2003;31:2-11.

34. Fulkerson JP, Langeland R: An alternative cruciate reconstruction graft: The central quadriceps tendon. Arthroscopy 1995;11:252-254.

35. Lee S, Seong SC, Jo H, et al: Outcome of anterior cruciate ligament reconstruction using quadriceps tendon autograft. Arthroscopy 2004; 20:795-802.

36. Theut PC, Fulkerson JP, Armour EF, et al: Anterior cruciate ligament reconstruction utilizing central quadriceps free tendon. Orthop Clin North Am 2003;34:31-39.

37. Staubli HU, Schatzmann L, Brunner P, et al: Quadriceps tendon and patellar ligament: Cryosectional anatomy and structural properties in young adults. Knee Surg Sports Traumatol Arthrosc 1996;4:100-110.

38. Chen CH, Chen WJ, Shih CH: Arthroscopic anterior cruciate ligament reconstruction with quadriceps tendon-patellar bone autograft. J Trauma 1999;46:678-682.

39. Buck BE, Malinin TI, Brown MD: Bone transplantation and human immunodeficiency virus. An estimate of risk of acquired immunodeficiency syndrome (AIDS). Clin Orthop 1989;240:129-136.

40. Harner CD, Thompson W, Jamison J, et al: The immunologic response of fresh frozen patellar tendon allograft ACL reconstruction. Paper presented at American Academy of Orthopaedic Surgeons, 1995, New Orleans, LA.

41. Jackson DW Simon TM, Kurzweil PR, et al: Survival of cells after intraarticular transplantation of fresh allografts of the patellar and anterior cruciate ligaments. DNA-probe analysis in a goat model. J Bone Joint Surg Am 1992;74:112-118.

42. Jackson DW, Grood ES, Goldstein JD, et al: A comparison of patellar tendon autograft and allograft used for anterior cruciate ligament reconstruction in the goat model. Am J Sports Med 1993;21: 176185.

43. Nikolaou PK, Seaber AV Glisson RR, et al: Anterior cruciate ligament allograft transplantation. Long-term function, histology, revasculariza-tion, and operative technique. Am J Sports Med 1986;14:348-360.

44. Harner CD, Olson E, Irrgang JJ, et al: Allograft versus autograft anterior cruciate ligament reconstruction: 3- to 5-year outcome. Clin Orthop 1996;324:134-144.

45. Peterson RK, Shelton WR, Bomboy AL: Allograft versus autograft patellar tendon anterior cruciate ligament reconstruction: A 5-year follow-up. Arthroscopy 2001;17:9-13.

46. Shelton WR, Papendick L, Dukes AD: Autograft versus allograft anterior cruciate ligament reconstruction. Arthroscopy 1997;13:446-449.

47. Shino K, Nakata K, Horibe S, et al: Quantitative evaluation after arthro-scopic anterior cruciate ligament reconstruction. Allograft versus autograft. Am J Sports Med 1993;21:609-616.

51

Anterior Cruciate Ligament

Armando FF Vidal and Freddie H. Fu

Was this article helpful?

0 0
How To Bolster Your Immune System

How To Bolster Your Immune System

All Natural Immune Boosters Proven To Fight Infection, Disease And More. Discover A Natural, Safe Effective Way To Boost Your Immune System Using Ingredients From Your Kitchen Cupboard. The only common sense, no holds barred guide to hit the market today no gimmicks, no pills, just old fashioned common sense remedies to cure colds, influenza, viral infections and more.

Get My Free Audio Book


Post a comment