SEMITENDINOSUS TENDON AND THE KENNEDY LIGAMENT AUGMENTATION DEVICE IN ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

PETER J. FOWLER, MD, FRCS(C)

Reconstruction of the torn-assisted anterior cruciate ligament reconstruction may be accomplished by an arthroscopically assisted technique that uses a synthetically augmented semitendinosus tendon autograft. Augmentation is provided by the ligament augmentation device. The function of the composite graft, which is sufficiently strong to allow early stress, is based on the principle of load sharing. Adherence to standard principles of ligament surgery, strict attention to anatomic details, and precise surgical technique are essential if the final goal of a stable knee with full range of motion is to be achieved. KEY WORDS: anterior cruclate ligaments, reconstruction, technique, arthroscopically assisted, synthetic augmentation, autograft

The past 20 years have witnessed the development of numerous and varied surgical techniques that serve to restore stability to the anterior cruciate ligament (ACL)- deficient knee. Primary repair and reconstruction with and without augmentation and the use of autologous and allogous tissue and synthetic material in intra-articular and extra-articular procedures have been described in the literature. More recently, arthroscopically assisted meth- ods which again incorporate various techniques have been developed and are being perfected.

Reconstruction of the ACL can be accomplished by means of an arthroscopically assisted technique that uses either autogenous or allogous tissue and the ligament augmentation device (LAD; 3M, St Paul, MN). Standard principles of ligament surgery are adhered to in order to prevent graft impingement andexcursion. The compos- ite graft, which is comprised of the LAD plus a biologic graft, is sufficiently strong to allow stress from the outset. The gradual strengthening and maturation of the biologic component protects the polypropylene from fatigue fail- ure.

The concept of augmentation and the construction of a composite graft was developed by the late Dr J. C. Kennedy as a possible solution to the problem of insuf- ficient graft strength after ACL reconstruction. His ex- tensive experience with autogenous ACL reconstruction in both animals and humans, as well as the work of oth- ers, have shown not infrequently a functionally deficient graft and the return of symptomatic giving way. ~ Inad- equate intra-operative tensioning due to initial autograft weakness, as well autograft weakening before recolla-

From the Section of Sport Medicine, University of Western Ontario, London, Ontario, Canada.

Address reprint requests to Peter J. Fowler, MD, FRCS(C), Box 5339, Postal Station A, London, Ontario, Canada N6A 5A5,

Copyright �9 1992 by W. B. Saunders Company 1048-6666/92/0202-0012505.00/0

genizing and restrengthening, were recognized as two specific problems that contributed to these unsatisfactory results. 1'2 This knowledge prompted the addition of me- chanical augmentation to autologous tissue.

The LAD functions to protect the biologic tissue during revascularization and to provide it with initial strength. The composite graft can be adequately tensioned intra- operatively, eliminating pathological laxity and allowing earlier motion and functional rehabilitation.

BIOMECHANICS OF THE LAD

The LAD is a 1.5-mm thick polypropylene braid that is heat-sealed at each end to prevent unravelling. Its bio- mechanical properties include a tensile strength of 1,500 N, a decrease in tensile strength of approximately 9% at 500,000 cyclic loads, and a mean strain change of 3% after 1 million cyclic loads. 1'3 The device's stiffness is approx- imately double that of the ACL. With these characteris- tics the LAD should not develop laxity in the early post- operative period.

The tensile strength of the suture connection between the synthetic and biologic components has been shown in animal cadaver studies to be 400 N, which is more than adequate to allow the load sharing function of the LAD in the immediate postoperative phase. 1 Load sharing, which is a critical aspect of the augmentation concept, is most effective during the first postoperative year. In 2 weeks to 4 months postoperatively, the LAD carries a significant percentage of the load. 3'4 At the same time, as the biologic tissue shares some of this load, collagen or- ganization is 'stimulated and maturation of the tissue oc- curs. This maturation allows gradual acceptance of in- creased load by the biologic graft preventing the LAD from acting as an isolated synthetic prosthetic ligament, s

Operative Techniques in Orthopaedics, Vol 2, No 2 (April), 1992: pp 117-124 1 17

INDICATIONS

The LAD is indicated for use as augmentation for autog- enous or allograft tissue in ligament reconstruction sur- gery. More specifically, these include symptomatic func- tional ACL insufficiency, ACL insufficiency with repara- ble meniscal lesions, and acute ACL disruptions in healthy, active individuals. Relative contraindications may include previous intra-articular infection and open physes capable of significant growth.

THE USE OF THE SEMITENDINOSUS

There are a number of attractive aspects to the use of the semitendinosus tendon as the autologous tissue. The ex- tensor mechanism of the knee is not "r and while serious complications of patellar tendon grafts are not common occurrences, these have been documented. 6'7 Burks et al, in a recent canine study, 8 suggested that at 6 months after harvesting a patellar tendon graft, decreases of up to 30% in patellar tendon strength can occur. As well, they reported an average of a 10% decrease in pa- tellar tendon length. Such alterations in the extensor mechanism may be disabling.

The use of the semitendinosus would appear to be less subtraction from an already abnormal knee. Loss of this tendon seems to create a minimal deficit in hamstring strength that may be restored by rehabilitation. 9 Distally, the anatomic fixation of the tendon may be maintained and the need for mechanical fixation eliminated. "If the semi tendinosus is not of adequate size, it may be transected at its distal insertion, doubled, and used with the LAD as a free graft. Alternatively, the gracilis may be harvested using the same incision and technique and added to the composite graft.

In posterior cruciate ligament (PCL) reconstruction, the semitendinosus combined with gracilis and the LAD is our standard composite graft, s

PREOPERATIVE ASSESSMENT

A detailed history of the initial injury and subsequent functional instability is documented. Included in the standard radiographic analysis is a tunnel view, prefera- bly standing, to assess the intercondylar notch and the cartilage spaces of the tibiofemoral joint and magnetic resonance imaging of the acutely injured knee} ~

SURGICAL TECHNIQUE

A detailed examination of the knee under anesthesia pre- cedes every surgical procedure. One gram of cefazolin is routinely administered intravenously. The procedure is performed with the patient supine and the knees flexed 90 ~ over a break in the operating room table. A tourni- quet is placed high on the thigh which is supported by a leg holder. In situations where the diagnosis is not de- finitive, a diagnostic arthroscopy is performed before graft harvesting and preparation.

Fig 1. Incision sites over the insertion of the pes anserinus and the distal intermuscular septum.

Fig 2. The fascial connections of the semitendinosus are re- leased.

118 PETER J. FOWLER

GRAFT HARVEST

The semitendinosus tendon is harvested through a 3-crn longitudinal incision overlying the pes anserinus inser- tion. The distal end of the semitendinosus tendon is ex- posed (Fig 1). The fascial connection between the semi~ tendinosus and the medial gastrocnemius is completely released (Fig 2). This is an important step, otherwise the tendon stripper can be derailed by this fascial connection

and a semitendinosus graft of inadequate length may re- sult.

The tendon stripper is used to transect the semitendi- nosus proximally (Figs 3 and 4). The tendon is then dis- sected along its musculotendinous junction to its distal insertion and separated from the insertion of the gracilis tendon (Fig 4).

SUTURING OF LAD A 6-ram wide LAD of appropriate length is selected. This is placed on the semitendinosus tendon and held se- curely with bulldog clamps (Fig 5). One heavy absorb- able suture is used to tag the end of the tendon and a similar suture anchors the end of the LAD here. With a 00 absorbable suture, the LAD is secured to the tendon. A running suture is used and an effort is made to tube the biologic tissue around the LAD (Fig 5). At the distal 3 cm of the composite graft are placed interrupted sutures of a 00 nonabsorbable material. A tendon leader is attached to the composite graft using a heavy suture (Fig 6). This step facilitates the eventual passage of the composite graft through the tibial tunnel and over the top to the lateral femur.

ACCESS TO THE OVER-THE-TOP POSITION A longitudinal incision is made over the iliotibial band just proximal to the lateral femoral condyle. The iliotibial band is split in line with its fibres just anterior to the

Fig 3. (A,B) A tendon stripper is used to harvest the semi~ tendinosus tendon. Fig 4. A graft of adequate length is obtained.

SEMITENDINOSUS ACL RECONSTRUCTION WITH THE LAD 119

Fig 5. The graft is tubed around the LAD using a running suture.

lateral intermuscular septum and the vastus lateralis musculature is lifted from the intermuscular septum. A 1.5-cm aperture is now made through the intermuscular septum just proximal to Kaplan's fibres.

INTRODUCTION OF THE ARTHROSCOPE

At arthroscopy any intra-articular meniscal or chondral lesions are treated. Synovium and remnants of ACL are then removed from the lateral femoral condyle in the notch using the motorized resector through an anterome- dial portal. This exposes the over-the-top position. A

Fig 7. The femoral channel is chamfered.

/ I /

GRAFT AD)

TENDON LEADER

Fig 6. The composite graft is attached to the tendon leader.

\

TIBIAL DRILL GUIDE

UIDE PIN

Fig 8. A tibial drill guide is used to facilitate pin placement.

120 PETER J. FOWLER

long-handled narrow-shaft curette is used to groove a 5- to 6-mm bonychanne l into the lateral femoral condyle. This, which creates a more anatomic graft placement, is carefully chamfered with a 6-mm long-handled rasp (Fig 7).

PREPARATION OF THE TIBIAL TUNNEL

Using a tibial drill-guide placed in the anteromedial as- pect of the ACL insertion,- a guide pin is "introduced through the previous pes anserinus incision (Fig 8). The guide pin is placed approximately 30 o to the articular sur- face of the anterior tibia. The composite graft is routinely sized; however, a tunnel created by a 6-ram reamer over the guide pin is generally adequate to allow graft pas- sage.

In acute ACL reconstructions the tibial stump of the torn ACL is retained and the composite graft is passed through it. This is an effort to preserve some of the func- tion of the nerve mechanoreceptors that have been iden- tiffed and described histologically, 13 many of which are located near the tibial insertion of the ACL.

stainless-steel wire is attached through the eye of the gaff hook and brought into the knee (Fig 9). One end of this wire remains at the lateral incision held with a haemostat, and the other end is brought out through the tibial tunnel using an arthroscopy grasper. The tendon leader and graft, attached to this wire, are then pulle d through the tibial tunnel and intercondylar notch, through the over- theLtop groove in the lateral femoral condyle, through the aperture in the lateral intermuscular septum, and into the lateral incision (Fig 10). Figure 11 illustrates the composite graft ideally placed through the notch and over-the-top.

TENSIONING OF THE COMPOSITE GRAFT

The knee is put through a range of motion. The graft is held securely and checked for any residual movement. With the knee in full extension, tension from 12 to 14 Ibs of pull is applied while the gr.aft is fixed to the lateral

POSITIONING OF THE COMPOSITE GRAFT

The "gaff hook," a large, round, eyed hook is introduced through the anterolateral portal, through the over-the- top groove, and brought out the lateral incision. A 00

2 0 WIRE

LARGE EYED HOOK

',,,~ "O

Fig 9. A gaff hook is used to bring a 00 wire into the knee joint from the lateral incision and then with an arthroscopy grasper out through the tibial tunnel.

Fig 10. The tendon leader is pulled from the lateral Incision through the tibial tunnel and around the femoral condyle.

SEMITENDINOSUS ACL RECONSTRUCTION WITH THE LAD 121

Fig 11. The composite graft through the notch and over the top.

femur with two barbed staples inserted in belt-buckle fashion (Fig 12).

Fig 13. The semitendinosus transected proximally and dis- tally and folded in half.

place (Fig 14). The preparation of the over-the-top posi- tion, the creation of the tibial tunnel, and the passage of the graft are performed as described previously. A screw and ligament washer can be used to fix the loop-end of the graft to the femur (Figs 15 and 16). Care should be taken not to include the LAD in the femoral fixation. Tibial fixation of the composite graft is accomplished with three motorized staples placed in sequence.

This composite graft, which should be even stronger with more tendon substance in the intra-articular posi- tion, may be used if the semitendinosus tendon is not impressive (Fig 17). Some use this technique routinely.

ALTERNATE METHOD--SEMITENDINOSUS FREE GRAFT

The semi tendinosus is harves ted as described and transected at its distal insertion as well. The semitendi- nosus is folded in half (Fig 13), and using a suture board, the LAD is sandwiched inside this loop and sutured in

REHABILITATION

Postoperatively, the leg is placed in a hinged knee brace. Flexion from neutral extension allowed a s wel l as pro- tected weight bearing for the first 6 weeks. The rehabil- itation regimen includes early motion and isometric quadriceps s t rengthening using functional exercises when possible. These are followed by progressive con- centric and then eccentric strengthening. Full rehabilita- tion of the knee should occur by 6 months after surgery. The use of an ACL protective brace is recommended for a minimum of 1 year after the patient returns to participa- tion in any ACL loading activity.

CLINICAL RESULTS

The initial 43 of 143 LAD-augmented ACL reconstruc- tions performed by Dr Kennedy using the Marshall- Macintosh technique were reviewed at a mean follow-up of 4 years. 1 These were compared with the same follow- \ up period of 45 patients who had undergone the same reconstruction procedure without augmentation. Evalu-

RECONSTRUCTED ACL, TENSIONED AND STAPLED TO DISTAL FEMUR

Fig 12. The graft is tensioned and stapled to the distal femur. The end of the composite graft is doubled over the first sta- ple and held with a second staple.

Fig 14. The LAD is sandwiched inside the loop of semiten- dinosus and sutured in place.

122 PETER J. FOWLER

Fig 15. The screw is placed through the loop of semitendi- nosus.

Fig 16. Biologic tissue isfixed to distal femur.

ation included subjective assessment , clinical examina- tion, anter ior laxity measu remen t with the KT-1,000 ar- thrometer , Cybex s t rength analysis, and functional test- ing by a o n e - l e g g e d h o p test . Pa t i en t s w i th LAD augmenta t ion showed a t rend towards bet ter results to objective laxity and functional testing than those in the n o n a u g m e n t e d group. On subjective evaluation, clinical e x a m i n a t i o n , a n d r a d i o g r a p h i c ana lys i s , the LAD- augmen ted group had significantly bet ter results.

The results of 100 of Dr Kennedy ' s augmen ted recon- structions were evaluated at a mean of 7.5 years after surgery. 14 This s tudy showed 91% good and excellent functional results with 96% of the patients satisfied that the p rocedure had been worthwhi le .

A large series with an over 5-year fol low-up is not avail- able on the LAD-augmented semi tendinosus technique. Our center 's 2- to 4-year fol low-up show stability equal to previously repor ted augmen ted quadriceps patellar ten- don grafts with fewer cases of restricted motion. A mul-

Fig 17. Composite graft with double length of tendon and LAD in place through the notch and over the top,

ticenter US trial also showed better subjective results, in- creased mot ion , and similar stability c o m p a r e d with n o n au g m en ted controls.

If the surgical principles of synthet ic augmenta t ion are adhered to, one can provide early stability to biologic tissue of relatively low tensile s trength. A result of good stability and mot ion can be expected.

REFERENCES

1. Roth JH, Kennedy JC, Lockstadt H, et al: Polypropylene braid aug- mented and nonaugmented intra-articular anterior cruciate llga- ment reconstruction. Am J Sports Me d 13:321-336, 1985

2. Jackson DW, Grood ES, Arnoczky SP, et al: Cruciate reconstruction using freeze dried anterior cruciate ligament allograft and a liga- ment augmentation device (LAD): An experimental study in a goat model. Am J Sports Med 15:528-538, 1987

3. VanKampen CL, Mendenhall HV, McPherson GK: Synthetic aug- mentation of biological anterior cruciate ligament substitutions, in Jackson DW, Drez D (eds): The Anterior Cruciate Deficient Knee-- New Concepts in Ligament Repair. St Louis, MO, Mosby, 1987, pp 226-238

4. Hanley P, Lew W, Lewis J: Load sharing and graft forces in anterior cruciate ligament reconstruction with the ligament augmentation device. Am J Sports Med 17:414-422, 1980

5. Fowler PJ, Capra SW: Anterior cruciate ligament reconstruction with the Kennedy ligament augmentation device, in: WN Scott (ed): Ligament and Extensor Mechanism Injuries of the Knee. St Louis, MO, Mosby, 1991, pp 301-310

6. Bonamo JJ, Krinick RM, Ronald M: Rupture of the patellar ligament after use of its central third for anterior cruciate ligament reconstruc- tion: A report of two cases. J Bone Joint Surg (Am) 66:1294-1297, 1984

7. Daniel DM, Woodward EP, Loose GM, et al: The Marshall- Mclntosh anterior cruciate ligament reconstruction with the Kennedy ligament augmentation device: Report of the United States clinical trials, in Friedman MJ, Ferkel RD (eds): Prosthetic Ligament Reconstruction of the Knee. Philadelphia, PA, Saunders, 1988, pp 71-78

SEMITENDINOSUS ACL RECONSTRUCTION WITH THE LAD 123

8. Burks TR, Haut RC, Lancaster RL: Biomechanical testing of patellar tendon after removal of its central one-third. Am J Sports Med 18:148-153, 1990

9. Kramer J, Nusca D, Fowler PJ: Concentric and eccentric knee flexor and extensor capability following ACL reconstruction using the semitendinosus tendon. Am J Sports Med 1991 (in press)

10. Messieh S, Fowler PJ: Anteroposterior radiographs of the osteoar- thritic knee. J Bone Joint Surg (Br) 72-B:639-640, 1990

11. Vellet DA, Marks P, Fowler PJ, et ah Accuracy of nonorthogonal magnetic resonance imaging in acute disruption of the anterior cru- date ligament. Arthroscopy 5(4):287-293, 1989

12. Vellet DA, Marks P, Fowler PJ, et ah Occult postraumatic osteo- chondral lesions of the knee: Prevalence, classification, and short- term sequelae evaluated with MR imaging. Radiology 178:271-276, 1991

13. Kennedy JC, Alexander IJ, Hayes K: Nerve supply of the human knee and its functional importance. Am ] Sports Med 10:329-335, 1982

14. Fowler PJ, MacKinlay D, Roth JH: Long term review of intra- articular ACL reconstructions with braided polypropylene. Clinical Residents Day University of Western Ontario 1989. The Proceedings of the International Society of the Knee, Rome, Italy, 1989

124 PETER J. FOWLER