ISAKOS
Journal

Graft Choice for ACL Reconstruction

Dr. Don Johnson
Assistant Professor Orthopedic Surgery
Director Sports Medicine Clinic
Carleton University
Ottawa On, Canada
Ph 613 520-3510
Fax 613 520-3974

History
The type of graft that the surgeon chooses for ACL reconstruction has evolved over the past few decades. Erickson popularized the patellar tendon graft autograft that Jones had originally described in 1960. This became the popular graft choice in the late 70's.

In the light of harvest site morbidity and post op stiffness associated with the patellar tendon graft, many surgeons began to look at other choices, semi- tendinosis, allograft, and synthetics. Fowler and then Rosenberg popularized the use of the semi-tendinosus. However even Fowler was not convinced of strength of the graft as he developed the LAD (ligament augmentation device) to supplement the semitendinosus. Gore-Tex, Leeds-Keio and Dacron were choices as an alternative synthetic graft. The initial experience was usually satisfactory. However, with the longer follow up, the results gradually deteriorated.

Allograft was another choice that avoided the problem of harvest site morbidity. The initial allograft that was sterilized with ethylene oxide had very poor results. The freeze dried, fresh frozen and cryopreserved are the most popular methods of preservation of allografts today. This has become a popular alternative to the autograft to reduce the harvest site morbidity, as well as the operative time.

The aggressive post-op rehab program advocated by Shelbourne in the 90's greatly diminished the problems associated with the patellar tendon graft. Prior to this change you had to be an athlete just to survive the rehab program.

There was renewed interest in the semi-tendinosis during the mid 90's. Biomechanical testing on the multiple bundle semitendinosus and gracilus grafts demonstrated it to be stronger and stiffer. This knowledge combined with improved fixation with devices such as the endo-button gave surgeons more confidence with no bone soft tissue grafts. The endo button made the procedure endoscopic, and eliminated the need for the second incision.

Fulkerson and others popularized the use of the quadriceps tendon graft. This again reduced the harvest morbidity, especially when only the tendon portion was harvested.

Shelbourne has described the use of the patellar tendon autograft from the opposite knee. With both the patellar tendon and the semitendinosus added to the list of graft choices, the need for the use of an allograft is minimized.

The latest twist in fixation is to use an interference fit screw to fixate the graft at the tunnel entrance. This produces a graft construct that is strong, short, and stiff. It means that now the surgeon just has to learn one technique for drilling the tunnels and he can chose whatever graft he wishes, hamstring, patellar tendon, quadriceps tendon or allograft.

Successful anterior cruciate ligament reconstruction is dependent on a number of factors including: patient selection, surgical technique, postoperative rehabilitation, and associated secondary restraint ligamentous instability. Errors in graft selection, tunnel placement, tensioning, or fixation methods chosen may also lead to graft failure. The comparison studies in the literature show that the outcome is almost the same irregardless of the graft choice. The most important aspect of the operation is to place the tunnels in the correct position. The choice of graft is really incidental.


Table 1
Table 1: The evolution in graft choice at the Sports Medicine Clinic.

Patellar Tendon
The patellar tendon graft was originally described as the gold standard graft. It is still the most widely used ACL replacement graft, but is not without it's problems.

Shelbourne has pushed the envelope further with the patellar tendon graft. He has recently reported on the use of the patellar tendon graft from the opposite knee, with an average return to play of 4 months post op.

The advantages of the patellar tendon graft are early bone to bone healing at 6 weeks, consistent size and shape of the graft and ease of harvest.

The disadvantages are the harvest site morbidity of patellar tendonitis and anterior knee pain, patellofemoral joint tightness with late chondromalacia, late patella fracture, late patellar tendon rupture, loss of range of motion, injury to the infra-patellar branch of the saphenous nerve. As you can see in the reference list, most of the complications are due to the harvest of the patellar tendon. This is still the main drawback to the use of the graft.

Semi-Tendinosus
With the improvement in the technique of the preparation of the multiple bundle graft, this graft choice has become more popular.

The advantages of the multiple bundle graft is that the it now is stronger and stiffer,


Grafts courtesy Dr. Steve Howell.

 

The disadvantages of the graft are the various methods use to fix the graft to bone, staples, endo-button, interference fit screws, the graft harvest can be difficult, the tendons can be cut off short, and there is a longer time for graft healing to bone, approximately 10-12 weeks.

Issues in Hamstring Grafts
There are several issues with hamstring grafts that have to be dealt with, such as the graft strength, fixation to bone, donor site morbidity and length of time to heal to the bone tunnel.

Graft Strength
Noyes originally reported that one strand is only 70% of the strength of the ACL. Sepaga subsequently reported that the semi-t and gracilis composite graft is equal to an 11 mm patellar tendon graft. Marder and Larson felt that the 4 bundle composite graft that is tensioned equally is 250% the strength of the normal ACL. Howell demonstrated that 4 bundles of composite graft has 4,300 N to failure compared to1750 N to failure for the native ACL.

Graft Stiffness
Brown has shown that a 4 bundle semi-t and gracilis composite graft is 2X the patellar tendon stiffness and 3X normal ACL stiffness.

Graft Fixation
The fixation has evolved from staples to endobutton to interference screws and ultimately to cross pins. Both the Endo button and tying sutures over periosteal buttons may be too weak and elastic, producing the bungee effect in the graft. This leads to a layer of fibrous tissue around the graft giving the tunnel enlargement appearance. This is a weak fixation. Isabashi and Fu showed that moving the fixation closer to the tunnel entrance shortened the graft and improved the results. Pinczewski showed no difference in outcome with interference screw fixation in semi-t and patellar tendon, except for harvest site morbidity (difficulty in kneeling) Pull out strength studies by several authors, Caborn, Weiler, Paulos, showed adequate pullout strength for the interference screw soft tissue fixation. (all above 400 N )

Graft Healing
Semitendinosus takes 10-12 weeks to heal to bone. During this period of time the graft has to be protected if the fixation is not strong.

Donor site Morbidity
In follow up the semitendinosus reconstruction has 3-21% of anterior knee pain compared to 12-40% for the patellar tendon reconstruction. Lipsome found there was no demonstrable weakness of knee flexion after hamstring harvest. Injury to the saphenous nerve is an uncommon complication of the tendon stripping.

Early aggressive rehabilitation
Aligetti and Marder showed there was no difference in outcome with early aggressive rehab. Therefore, the semitendinosus graft has been shown to withstand aggressive rehab, and early return to sports. Howell has also reported early return to sports without a brace at 6 months using cross pin femoral fixation.

Allograft
The main allure of the allograft is the absence of harvest site morbidity. However, the allograft did not initially have good reviews due to the ethylene oxide sterilization process. This caused the graft to be weak and fail easily. With the advent of the freeze dried and cryopreserved process there is minimal risk of disease transmission or graft weakness.

The advantages of the allograft are no harvest site morbidity, are available off the shelf.

The disadvantages of the allograft are the risk of disease transmission, a weak graft, if radiated or from an older patient, a longer time to incorporate into the bone tunnels, the graft is not universally available, and is expensive.

Quads tendon
The quadriceps tendon has gained popularity in the late 90's due to the ease of harvest and the large cross sectional size. Fulkerson has popularized this graft source. Day, Morgan and others have advocated the use of the graft harvested without a bone block from the patella. This further reduces the morbidity of the harvest.

The advantages of the quads tendon graft is less harvest site morbidity, and a larger cross sectional area of graft.

The disadvantages are harvest site morbidity, and the graft has a bone block on only one end of graft.

Synthetic
The initial allure of the synthetic was as an alternative to the patellar tendon graft harvest problems. However, with long term follow up the failures became unacceptable.

The advantages of synthetic grafts are no harvest site morbidity, no disease transmission.

The disadvantages are a higher rate of late graft failure, an increased risk of late infection, and they are expensive.

ACL Graft Choice References

Allografts

  • Jackson,D.W., and Kurzweil,P.R.: Allografts in knee ligament surgery. In Ligament and Extensor Mechanism of the Knee: Diagnosis and Treatment, pp.349-360. Edited by W.N. Scott. St. Louis, Mosby Year Book, 1991.
  • Jackson,D.W.; Windler,G.E.; and Simon,T.M.: Intraarticular reaction associated with the use of freeze-dried, ethylene oxide-sterilized bone-patella tendon-bone allografts in the reconstruction of the anterior cruciate ligament. Am.J. Sports Med., 18:1-10, 1990.
  • Newton,P.O.; Horibe,S.; and Woo,S.L.-Y.: Experimental studies on anterior cruciate ligament autograft and allografts. In Knee Ligaments: Structure, Function, Injuries, and Repair, pp. 389-399. Edited by D. Daniel, W.H. Akeson, and J.J. O'Connor. New York, Raven Press, 1990.
  • Nikolaou,P.K.; Seaber,A.V.; Glisson,R.R.; Ribbeck,B.M.; and Bassett, F.H., III: Anterior cruciate ligament allograft transplantation. Long-term function, histology, revascularization, and operative technique. Am.J. Sports Med., 14:348-360, 1986.
  • Noyes,F.R.; Barber,S.D.; and Mangine,R.E.: Bone-patellar ligament-bone and fascia lata allografts for reconstruction of the anterior cruciate ligament. J.Bone and Joint Surg., 72-A: 1125-1136, Sept. 1990
  • Roberts,T.S.;Drez,David,Jr.; McCarthy,William; and Paine,Russell: Anterior cruciate ligament reconstruction using freeze-dried, ethylene oxide-sterilized, bone-patellar tendon-bone allografts. Two year results in thirty- six patients. Am.J. Sports Med., 19:35-41, 1991.
  • Shino,K.;Inoue,M.;Horibe,S.;Hamada,M.; and Ono,K.: Reconstruction of the anterior cruciate ligament using allogeneic tendon: long-term followup. Am. J. Sports Med., 18:457-465, 1990.
  • Shino,Konsei; Inoue,Masahiro; Horibe,Shuji;Nagano,Juro; and Ono,Keiro: Maturation of allograft tendons transplanted into the knee. An arthroscopic and histological study. J. Bone and Joint Surg., 70-B(4):556-560, 1988.
  • Noyes FR, Barber-Westin SD. Arthroscopic-assisted allograft anterior cruciate ligament reconstruction in patients with symptomatic arthrosis. Arthroscopy. 1997 Feb;13(1):24-32.
  • Noyes FR, Barber-Westin SD Reconstruction of the anterior cruciate ligament with human allograft. Comparison of early and later results. J Bone Joint Surg Am. 1996 Apr;78(4):524-37.
  • Nin JR, Leyes M, Schweitzer D Anterior cruciate ligament reconstruction with fresh-frozen patellar tendon allografts: sixty cases with 2 years' minimum follow-up. Knee Surg Sports Traumatol Arthrosc. 1996;4(3):137-42.

Comparison Studies

  • Shelton WR, Papendick L, Dukes AD Autograft versus allograft anterior cruciate ligament reconstruction. Arthroscopy. 1997 Aug;13(4):446-9.
  • Harner CD, Olson E, Irrgang JJ, Silverstein S, Fu FH, Silbey M Allograft versus autograft anterior cruciate ligament reconstruction: 3- to 5-year outcome. Clin Orthop. 1996 Mar;(324):134-44.
  • Victor J, Bellemans J, Witvrouw E, Govaers K, Fabry G Graft selection in anterior cruciate ligament reconstruction--prospective analysis of patellar tendon autografts compared with allografts. Int Orthop. 1997;21(2):93-7.

Synthetics

  • Larson, R.L.: Gore-tex anterior cruciate ligament reconstruction. In Ligament and Extensor Mechanism Injuries of the Knee: Diagnosis and Treatment, pp. 319-329. Edited by W.N. Scott. St. Louis, Mosby Year Book, 1991.
  • Woods,G.A.;Indelicato,P.A.; and Prevot,T.J.: The Gore-tex anterior cruciate ligament prosthesis. Two versus three year results. Am. J. Sports Med., 19: 48-55, 1991.
  • Maletius W, Gillquist J Long-term results of anterior cruciate ligament reconstruction with a Dacron prosthesis. The frequency of osteoarthritis after seven to eleven years. Am J Sports Med. 1997 May-Jun;25(3):288-93.

Hamstring Grafts

  • Lipscomb,A.B.; Johnston,R.K.; Snyder,R.B.; Warburton,M.J.; and Gilbert, P.P.: Evaluation of hamstring strength following use of semitendinosus and gracilis tendons to reconstruct the anterior cruciate ligament. Am.J. Sports Med., 10:340-342, 1982.
  • Zarins,Bertram, and Rowe,C.R.: Combined anterior cruciate-ligament reconstruction using semitendinosus tendon and iliotibial tract. J. Bone and Joint Surg., 68-A: 160-177, Feb. 1986.
  • Sgaglione,N.A.; Warren,R.F.; Wickiewicz,T.L.; Gold,D.A. and Panariello,R.A.: Primary repair with semitendinosus tendon augmentation of acute anterior cruciate ligament injuries. Am.J. Sports Med., 18:64-73, 1990.
  • Giurea M, Zorilla P, Amis AA, Aichroth P Comparative pull-out and cyclic-loading strength tests of anchorage of hamstring tendon grafts in anterior cruciate ligament reconstruction. Am J Sports Med. 1999 Sep-Oct;27(5):621-5.
  • Oates KM, Van Eenenaam DP, Briggs K, Homa K, Sterett WI Comparative injury rates of uninjured, anterior cruciate ligament-deficient, and reconstructed knees in a skiing population. Am J Sports Med. 1999 Sep-Oct;27(5):606-10.
  • Brahmabhatt V, Smolinski R, McGlowan J, Dmochowski J, Ziv I Double-stranded hamstring tendons for anterior cruciate ligament reconstruction. Am J Knee Surg. 1999 Summer;12(3):141-5.
  • Muneta et al. Two-bundle reconstruction of the anterior cruciate ligament using semitendinosus tendon with endobuttons: operative technique and preliminary results.
    Arthroscopy. 1999 Sep;15(6):618-24.
  • Howell SM et al. Comparison of endoscopic and two-incision techniques for reconstructing a torn anterior cruciate ligament using hamstring tendons. Arthroscopy. 1999 Sep;15(6):594-606.
  • Eriksson K, et al. Semitendinosus tendon regeneration after harvesting for ACL reconstruction. A prospective MRI study. Knee Surg Sports Traumatol Arthrosc. 1999;7(4):220-5.
  • Corry IS, Webb JM, Clingeleffer AJ, Pinczewski LA Arthroscopic reconstruction of the anterior cruciate ligament. A comparison of patellar tendon autograft and four-strand hamstring tendon autograft. Am J Sports Med. 1999 Jul-Aug;27(4):444-54.
  • Barber FA Tripled semitendinosus-cancellous bone anterior cruciate ligament reconstruction with bioscrew fixation. Arthroscopy. 1999 May;15(4):360-7.
  • Weiler A, Hoffmann RF, Sudkamp NP, Siepe CJ, Haas NP Replacement of the anterior cruciate ligament. Biomechanical studies for patellar and semitendinosus tendon fixation with a poly(D,L-lactide) interference screw. Unfallchirurg. 1999 Feb;102(2):115-23.
  • Siegel MG, Barber-Westin SD Arthroscopic-assisted outpatient anterior cruciate ligament reconstruction using the semitendinosus and gracilis tendons. Arthroscopy. 1998 Apr;14(3):268-77.
  • Simonian PT, Williams RJ, Deng XH, Wickiewicz TL, Warren RF Hamstring and patellar tendon graft response to cyclical loading. Am J Knee Surg. 1998 Spring;11(2):101-5.
  • Rosenberg TD, Deffner KT ACL reconstruction: semitendinosus tendon is the graft of choice. Orthopedics. 1997 May;20(5):396, 398.
  • Simonian PT, Harrison SD, Cooley VJ, Escabedo EM, Deneka DA, Larson RV Assessment of morbidity of semitendinosus and gracilis tendon harvest for ACL reconstruction. Am J Knee Surg. 1997 Spring;10(2):54-9.
  • Puddu G: Method for reconstruction of the anterior cruciate ligament using the semitendinosus tendon. Am J Sports Med 8: 402-404, 1980.
  • Gomes JLE, Marczyk LRS: Anterior cruciate ligament reconstruction with a loop or double thickness of semitendinosus tendon. Am J Sports Med 12: 199-203, 1984.
  • Zaricznyj B: Reconstruction of the anterior cruciate ligament of the knee using a double tendon graft. Clin Orthop 220:162-175, 1987.
  • Freidman MJ, Arthroscopic Semitendinosus Reconstruction for Anterior Cruciate Deficiency. Techniques in Orthopedics 2:74-80, 1988.
  • Brown CH.Steiner ME, Carson EW: The Use of Hamstring Tendons for Anterior Cruciate Reconstruction, Technique and Results. Clinics in Sports Medicine, Vol 12, No 4; 723-756.
  • Wilson WJ, Lewis F, Scranton PE: Combined Reconstruction of the Anterior Cruciate Ligament in Competitive Athletes. Journal of Bone and Joint Surgery, Vol 72A, No 5, 742-748, 1990.
  • Sgaglione NA, Warren RF, Wickiewicz TL, et al: Primary repair with semitendinosus tendon augmentation of acute anterior cruciate ligament injuries. Am J Sports Med 18: 64-73, 1990.
  • Sgaglione NA, Del Pizzo W, Fox JM, et al: Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: Comparison of results with and without braided polypropylene augmentation. Arthroscopy 8: 65-77, 1992.
  • Noyes FR, Butler DL, Grood ES, Zernicke RF, Hefzy MS; Biomechanical Analysis of Human Ligament Grafts Used In Knee Ligament Repairs and Reconstructions. The Journal of Bone and Joint Surgery, Vol 66A, No 3; p344-352, 1984.
  • To JT, Howell SM, Hull ML: Biomechanical properties of the double looped hamstring graft and three anterior cruciate ligament graft fixations. AAOS Instructional Course Atlanta 1996.
  • Brown C: Biomechanics of the semitendinosus and gracilus tendon grafts. AOSSM Toronto Canada 1995.
  • Pinczewski L, Clinical Results; Pinczewski Endoscopic Hamstring Technique Utilizing the DonJoy RCI Fixation Screw 1994.
  • Lipsomb AB, Johnston RK, Snyder RB, et al: Evaluation of hamstring strength following use of the semitendinosus and gracilus tendons to reconstruct the anterior cruciate ligament. Am J Sports Med 10: 340-342 1982.
  • Yasuda K, Tsujino J, Ohkoshi y, Tanabe Y, Kaneda K: Graft site morbidity with autogenous semitendinosus and gracilus tendons. Am J Sports Med 23: 706-713, 1995.
  • Cross MJ, Roger G, Kujawa P, et al: Regeneration of the semitendinosus and gracilus tendons following their transection for repair of the anterior cruciate ligament. Am J Sports Med 20: 221-223, 1992.

Patellar Tendon Grafts

  • Jones KG, Reconstruction of the anterior cruciate ligament using the central one-third of the patellar ligament. J Bone Joint Surg Am. 1970 Jun;52(4):838-9.
  • Yasuda,Kazunori;Tomiyama,Yuichi;Ohkoshi,Yasumitsu:and Kaneda, Kiyoshi: Arthroscopic observations of autogeneic quadriceps and patellar tendon grafts after anterior cruciate ligament reconstruction of the knee. Clin. Orthop., 246:217-224, 1989.
  • Vasseur,P.B.;Rodrigo,J.J.;Stevenson,Sharon;Clark,Geoffrey; and Sharkey, Neil: Replacement of the anterior cruciate ligament with a bone-ligament-bone anterior cruciate ligament allograft in dogs. Clin.Orthop.,219-277,1988.
  • Shelbourne,K.D.;Whitaker,H.J.;McCarroll,J.R.;Reittig,A.C. and Hirschmann, L.D.: Anterior cruciate ligament injury: evaluation of intraarticular reconstruction of acute tears without repair. Two to seven year followup of 155 athletes. Am. J. Sports Med., 18: 484-489, 1990.
  • O'Brien,S.J.; Warren,R.F.; Pavlov, Helene; Panariello, Robert; and Wickiewicz,T.L.: Reconstruction of the chronically insufficient anteriorncruciate ligament with the central third of the patellar ligament. J. Bone and Joint Surg., 73-A: 278-286, Feb. 1991.
  • Randall RL, Wolf EM, Heilmann MR, Lotz J Comparison of bone-patellar tendon-bone interference screw fixation and hamstring transfemoral screw fixation in anterior cruciate ligament reconstruction. Orthopedics. 1999 Jun;22(6):587-91.
  • Kleipool AE, Zijl JA, Willems WJ Arthroscopic anterior cruciate ligament reconstruction with bone-patellar tendon-bone allograft or autograft. A prospective study with an average follow up of 4 years. Knee Surg Sports Traumatol Arthrosc. 1998;6(4):224-30.
  • Kartus J, Stener S, Lindahl S, Eriksson BI, Karlsson J Ipsi- or contralateral patellar tendon graft in anterior cruciate ligament revision surgery. A comparison of two methods. Am J Sports Med. 1998 Jul-Aug;26(4):499-504.
  • Aune AK, Ekeland A, Cawley PW Interference screw fixation of hamstring vs patellar tendon grafts for anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 1998;6(2):99-102.
  • Bach BR Jr, Tradonsky S, Bojchuk J, Levy ME, Bush-Joseph CA, Khan NH Arthroscopically assisted anterior cruciate ligament reconstruction using patellar tendon autograft. Five- to nine-year follow-up evaluation. Am J Sports Med. 1998 Jan-Feb;26(1):20-9.
  • 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 Nov-Dec;25(6):786-95.

Comparison Studies

  • Feagin JA Jr, Wills RP, Lambert KL, Mott HW, Cunningham RR Anterior cruciate ligament reconstruction. Bone-patella tendon-bone versus semitendinosus anatomic reconstruction. Clin Orthop. 1997 Aug;(341):69-72.
  • Rowden NJ, Sher D, Rogers GJ, Schindhelm K Anterior cruciate ligament graft fixation. Initial comparison of patellar tendon and semitendinosus autografts in young fresh cadavers. Am J Sports Med. 1997 Jul-Aug;25(4):472-8.
  • Grontvedt T, Engebretsen L, Bredland T Arthroscopic reconstruction of the anterior cruciate ligament using bone-patellar tendon-bone grafts with and without augmentation. A prospective randomised study. J Bone Joint Surg Br. 1996 Sep;78(5):817-22.
  • O'Neill DB Arthroscopically assisted reconstruction of the anterior cruciate ligament. A prospective randomized analysis of three techniques. J Bone Joint Surg Am. 1996 Jun;78(6):803-13.
  • Holmes PF, James SL, Larson RL, et al: Retrospective direct comparison of three intra-articular anterior cruciate ligament reconstructions. Am J Sports Med 19: 596-600 1987.
  • Marder RA, Rasking JR, Carroll M; Prospective evaluation of arthroscopically assisted anterior Cruciate Ligament Reconstruction, Patellar Tendon vs Semitendinosus and Gracilus Tendons. American Journal of Sports Medicine Vol 19, No 5; p 478-484.
  • Steiner ME, Hecker AT, Brown CH, Hayes WC; Anterior Cruciate Ligament Graft Fixation, Comparison of Hamstring and Patellar Tendon Grafts. Am J of Sports Med Vol 22, No 2: 240-247, 1994.

Quadriceps Tendon Grafts

  • Chen CH, Chen WJ, Shih CH Arthroscopic anterior cruciate ligament reconstruction with quadriceps tendon-patellar bone autograft. J Trauma. 1999 Apr;46(4):678-82.

Complications

  • Clatworthy MG, Annear P, Bulow JU, Bartlett RJ Tunnel widening in anterior cruciate ligament reconstruction: a prospective evaluation of hamstring and patella tendon grafts. Knee Surg Sports Traumatol Arthrosc. 1999;7(3):138-45.
  • Sachs, R.A.; Daniel,D.M.; Stone,M.L.; and Garfein,R.F.: Patellofemoral problems after anterior cruciate ligament reconstruction. Am. J. Sports Med., 17:760-765, 1989.
  • Shelbourne,K.D.; Wilckens,J.H.; Mollabashy,Alla; and DeCarlo,Mark: Arthrofibrosis in acute anterior cruciate ligament reconstruction. The effect of timing of reconstruction and rehabilitation. Am. J. Sports Med., 19:332-336, 1991.
  • Miller MD, Nichols T, Butler CA Patella fracture and proximal patellar tendon rupture following arthroscopic anterior cruciate ligament reconstruction. Arthroscopy. 1999 Sep;15(6):640-3.
  • Ouweleen KM, McElroy JJ A unique complication following arthroscopic anterior cruciate ligament reconstruction. Arthroscopy. 1995 Apr;11(2):225-8.
  • Bonatus TJ et al. Patellar fracture and avulsion of the patellar ligament complicating arthroscopic anterior cruciate ligament reconstruction. Orthop Rev. 1991 Sep;20(9):770-4.
  • Benson ER et al. A delayed transverse avulsion fracture of the superior pole of the patella after anterior cruciate ligament reconstruction. Arthroscopy. 1998 Jan-Feb;14(1):85-8.
  • Marumoto JM et al. Late patellar tendon ruptures after removal of the central third for anterior cruciate ligament reconstruction. A report of two cases. Am J Sports Med. 1996 Sep-Oct;24(5):698-701. Review.
  • Shaffer BS, et al. Patellar tendon length change after anterior cruciate ligament reconstruction using the midthird patellar tendon. Am J Sports Med. 1993 May-Jun;21(3):449-54.
  • Johnson DL, Either DB, Vanarthos WJ Herniation of the patellar fat pad through the patellar tendon defect after autologous bone-patellar tendon-bone anterior cruciate ligament reconstruction. A case report. Am J Sports Med. 1996 Mar-Apr;24(2):201-4.
  • Kartus J, Magnusson L, Stener S, Brandsson S, Eriksson BI, Karlsson J Complications following arthroscopic anterior cruciate ligament reconstruction. A 2-5-year follow-up of 604 patients with special emphasis on anterior knee pain. Knee Surg Sports Traumatol Arthrosc. 1999;7(1):2-8.
  • Marumoto JM, Mitsunaga MM, Richardson AB, Medoff RJ, Mayfield GW Late patellar tendon ruptures after removal of the central third for anterior cruciate ligament reconstruction. A report of two cases. Am J Sports Med. 1996 Sep-Oct;24(5):698-701.
  • Sachs RA, Daniel D, Stone ML, Garfein RF: Patellofemoral problems after Anterior Cruciate Ligament Reconstruction. Am J Sports Med 17:760-765 1989.