Biazzo A, Manzotti A, Motavalli K, Confalonieri N.
Key words: bone- patellar tendon- bone; press-fit; anterior cruciate ligament; knee; arthroscopy; interference screw.
The aim of this paper is to present our 20-year follow-up with femoral press-fit fixation in anterior cruciate ligament reconstruction using bone-patellar tendon-bone autograft, comparing the results with an omogeneous group of patients who underwent the same procedure with femoral interference screw fixation.
The patient population was randomly placed in two groups: group A (53 patients), who underwent femoral screw fixation; group B (56 patients), who underwent femoral press-fit fixation. For tibial fixation were used screws in both groups.
At last follow-up (average 19,5 years), 28% of patients in group A and 64% of patients in group B had excellent International Knee Documentation Committee score (grade A); 66% of patients in group A and 32% of patients in group B had good International Knee Documentation Committee scores (grade B); 6% of patients in group A and 4% in group B had fair scores (grade C). The difference between the two groups was not statistically significant (p=0,002).
Our results are similar to those reported in the literature and prove that femoral press-fit fixation has the same efficacy of screw fixation but avoids all disadvantages of hardware. Our most important complication was anterior algodystrophy, observed in 17% of patients in group A and 13% of patients in group B.
Femoral press-fit fixation of bone- patellar tendon- bone autograft is an efficient procedure; it provides stable fixation at low cost, it ensures unlimited bone-to-bone healing and high primary stability, avoiding the disadvantages of hardware fixation and the need for removal in case of revision. It is a technically high demanging procedure and it should be avoided in patient with poor bone quality and with pre-existing patello-femoral problems.
The anterior cruciate ligament (ACL) is one of the most frequently injured ligaments in the human body. So ACL reconstruction has become a common surgical procedure in orthopaedic surgery. Many different grafts have been used but the bone -patellar tendon-bone (B-PT-B) autograft is considered the gold standard [1,2,9,20,23,31]. The main advantage of B-PT-B autograft include high load to failure, adequate stiffness and rapid bone healing . Various techniques have been used for femoral fixation of the graft, among which interference screws have been the most widely used, although various complications have been reported, including divergent screw placement, possible impingement and abrasion . Metal interference screws are difficult to remove in case of revision surgery and they may also produce disturbance in postoperative magnetic resonance imaging. To avoid difficulties related to fixation devices, in 1987 Hertel developed a femoral press-fit fixation and in 1989 a tibial press-fit fixation . Then several authors like Boszotta , Paessler  and others [3,25] developed similar techniques. Several biomechanical studies have been performed in order to compare the press-fit fixation with commonly used implant fixations. The press-fit fixation has been shown to have similar pull-out strenght and stiffness compared to fixation with interference screws in animal models [13,19,24,26,27,30].
The aim of this paper is to present our 20-year follow-up with femoral press-fit fixation in ACL reconstruction using B-PT-B autograft, comparing the results with an omogeneous group of patients who underwent the same procedure with femoral interference screw fixation.
Materials and Methods
Between September 1994 and September 1997 the authors performed 109 ACL reconstructions using BPTB autograft.
Inclusion criterion was: documented ACL lesion associated with subjective knee instability. Exclusion criteria were: concurrent fracture of the knee and posterior cruciate ligament injury. The study design was approved by the local ethics committee and all patients gave informed consent prior to inclusion in this trial.
This patient population was randomly placed in two groups, regarding the treatment. In the first group (Group A; n= 53), femoral interference screw fixation technique was used; while in the second group (Group B; n= 56), femoral press-fit fixation was used. In both groups was used the tibial interference fixation.
Group A: 53 patiens randomly assigned to femoral and tibial interference screw fixation with screw (Kurosaka screw, Depuy, Warsaw, IN) . We had 34 male and 19 female. Mean age was 28 years (range 15-41); the left knee was affected in 29 patients, the right knee in 24. Seventeen were professional athlets. The time between injury and surgery ranged from 1 month to 25 months (median 6 months). Twelve patients had undergone previous knee arthroscopies for meniscus tears. During ACL reconstruction we performed 18 meniscectomies, 13 medial and 5 lateral.
Group B: 56 patients randomly assigned to femoral press-fit fixation. We had 41 male and 15 female. Mean age was 23 years (range 18-39); the left knee was affected in 24 patients, the right knee in 32. None of them were athlets, but all were amateur sport players. The time between injury and surgery ranged from 20 days to 18 months (median 5 months). Seven patients had undergone previous knee arthroscopies. During ACL reconstruction we performed 13 meniscectomies, 5 medial and 8 lateral.
Clinical evaluation was assessed with International Knee Documentation Committee score (IKDC)  and with arthrometer KT-1000. The data was stored on a Microsoft Excel database. Statistical analysis was performed using t-student test. Significance was set < 0,001.
Surgical technique and rehabilitation
All operations were carried out under general or spinal anesthesia and tourniquet. A diagnostic arthroscopy was perfomed to verify the rupture of the ACL and to address associated injuries as mentioned above. After removing the ACL remnants the femoral notch was prepared. The medial wall of the lateral femoral condyle was debrided until the posterior arch of the notch was clearly visible. Then a midline incision over the medial edge of the ipsilateral patellar tendon was made. The B-PT-B autograft was 10 mm wide and harvested with 20-25 mm of bone from the patellar and tibial tubercle. The bone blocks were formed to a trapezoid shape by using an oscillating saw. The tibial and femoral tunnels were reamed to an appropriate size depending on the width of the autograft bone blocks (in group B, 1 mm undersized to the bone graft). Then the graft was pulled through the tunnels with out-in technique for the tibial autograft and in-out technique for the femoral autograft, using a pull-through suture, so that the patella bone block was within the femoral tunnel and the tibial bone block was within the tibial tunnel. The graft was positioned so that no bone protruded into the joint. In group A an interference screw of Kurosaka (average dimension 7 x 25 mm) was used both in the femoral and in the tibial tunnel to fix the bone block. In group B, an interference screw of Kurosaka (average dimension 7 x 25 mm) was used to fix the tibial bone block, while the fixation of the femoral autograft was a press-fit fixation.
Rehabilitation differs in group A and B.
Group A. Standard protocol with brace adjusted to allow 0 to 90 degrees of flexion during the first 2 weeks, then full range of motion was allowed. Full weight-bearing was permitted.
Group B. A fixed splint in full extension was worn during the first 2 weeks. The patient walked with toe touch weight-bearing using crutches. The immediate active quadriceps isometric exercises were started. On the fifteenth postoperative day, the brace was adjusted to allow motion between 0-60 degrees of flexion. The patient continued walking with toe touch weight-bearing using crutches. Four weeks after surgery, the brace was adjusted to allow between 0 to 90 degrees of flexion and the patient was permitted to bear 50% of his weight. At five weeks the brace was adjusted to allow 0 to 120 degrees of flexion and full weight-bearing was permitted. Six weeks after surgery full flexion was allowed. Swimming and bicycle without resistance were allowed.
Average follow-up was 19,5 years (range 18-21 years). None of the patients returned complaining of instability. All patients returned to normal activities such as moderate physical work, running or jogging.
At the last follow-up, 28% of patients in group A and 64% of patients in group B had excellent IKDC score (grade A); 66% of patients in group A and 32% of patients in group B had good IKDC score (grade B); 6% of patients in group A and 4% in group B had fair IKDC score (grade C) (Table 1). The difference between the two groups was not statistically significant (p=0,002).
Using the KT-1000 arthrometer, the side-to-side difference was 1-2 mm in 35% and 68% of patients respectively in group A and B. The side-to-side difference was 3-5 mm in 65% and 32% of patients respectively in group A and B. We did not find side-to-side differences > 5 mm in both groups (Table 2). No statistically significant difference between the two groups was observed (p=0,002).
The most frequent complication was muscle atrophy (21% in group A and 25% in group B), followed by anterior algodystrophy (17% in group A and 13% in group B). Arthrofibrosis occurred in 6% of patients in group A and 11% in group B, all treated with arthroscopical arthrolysis. Two patients in group A had to be revised because of Cyclops syndromes. All complications are listed in Table 3.
The concept of press-fit fixation was introduced by Hertel in 1987 . It is a simple technique that offers several advantages, including biological graft healing, the absence of any intra-articular hardware making easier revision surgery, and avoidance of the cost of femoral implants . Different authors [5,6] reported no statistical difference in failure or stiffness comparing a press-fit bone plug with a patellar tendon bone plug with interference screw fixation. Several biomechanical studies have been conducted in order to compare the press-fit fixation with commonly used hardware fixations. The press-fit fixation has been shown to have similar pull-out strength  and stiffness  when compared to fixation with interference screw in animal models. In 1995 Malek et al.  performed a cadaveric study between femoral press-fit fixation and interference fixation with Kurosaka’s screw. They could find two reasons for the success of press-fit fixation: the power of press- fit in an undersized bone tunnel and the angle between tendon and bone plug inside the femoral tunnel. This angle decreases from extension to flexion of the knee and pull-out of the bone is possible only beyond 60 degrees of flexion. This is the rationale we allow knee flexion beyond 60 degrees only during the fifth-sixth week, when the autograft is incorporated into the femoral tunnel. Papageorgiou et al.  demostrated that the bone plugs are fully incorporated after a healing period of 6 weeks in an animal model.
Advantages of press-fit fixation include unlimited bone-to-bone healing and avoidance of all disadvantages associated with hardware fixation, such as graft laceration, bioincompatibility, biodegradability or allergic reactions [16,18]. Limitations of this technique include a certain degree of technical difficulty, limited applicability in patients with poor bone quality and patello-femoral problems.
Few reports have analized the long-term results of press-fit fixation [3,7,8,11,33] and only one author have performed a matched-pair study between femoral interference screw and press-fit fixation .
The original technique of ACL reconstruction using B-PT-B press-fit fixation was presented by Hertel in 1990 during the ESSKA congress in Stockholm , but the 10-year results were published in 2005 . They used press-fit fixation both for femoral and tibial bone plugs. Assessment using IKDC score revealed 84% of patients had normal or nearly normal knee joints at follow-up, 15% had abnormal knee joints and 1% had severly abnormal knee joint. The average injured-uninjured KT-1000 difference was 1,8 mm. Fifty-nine % had a difference of 1-2 mm, 41% a difference of 3-5 mm to the opposite knee. The most frequent reported complication was ectopic bone formation, observed in 31% of patients and most often located at the apex of the patella.
Gobbi et al.  reported the 5-year results of femoral press-fit fixation of B-PT-B in ACL reconstruction in 40 athletes. The IKDC knee score revealed 85% of patients with a normal or nearly normal knee joint. They had one pull-out of the tibial bone block that needed revision surgery and four patients with patellar pain who needed second-look arthroscopy. Al-Husseiny et al.  presented a retrospective study of 42 ACL reconstructions using B-PT-B and femoral press-fit fixation. At a medium follow-up of 29 months, IKDC knee score revealed 88% of the patients with normal or nearly normal knee joint, 10% as abnormal and 2% as severly abnormal. Using KT-1000 arthrometer the side-to-side difference was 2 mm or less in 40 patients and 3-5 mm in 2. Thirty-five % of patients had irritation on the donor site and 3 underwent late arthroscopies due to arthrofibrosis. In one case they had fracture of the patellar bone plug during impaction in the femoral tunnel.
Widuchowski et al.  reported the longest follow-up (15 years) of femoral press-fit fixation in ACL reconstruction using B-PT-B autograft. In a group of 52 patients, IKDC knee score revealed 75% of patients had normal or nearly normal knee joint. Post-operative complications were observed in 5 patients, of which one developed a superficial wound infection and 4 developed arthrofibrosis which required second-look arthroscopy in 2 of them. Felmet  reported the 10-year results of implant-free press-fit fixation for B-PT-B ACL reconstruction: IKDC score of the 148 patients enrolled in the study revealed 87% of normal or nearly normal knee joints. As major complications he described 8 Cyclops syndromes that need second-look arthroscopy and as local complications he reported numbness of the skin in 40% of the patients. The only matched-pair study between 2 techniques of fixation we could find was that of Sarzaeem et al. , who reported the short terms results of 158 patients, randomly assigned to femoral press-fit fixation and interference screw fixation. Assessment with IKDC score revealed 83% and 85% of normal or nearly normal knee joints in press-fit and screw group respectively (p > 0.05). The mean laxity assessed using a KT-1000 arthrometer improved to 2.7 and 2.5 mm in press-fit and screw group, respectively. As major complications they reported only 7 cases of infections (3 deep infections). Patello-femoral pain was observed in 12.7% of patients in press-fit group and 15.3% of patients in screw group, showing no significant differences (p > 0.05).
The donor site morbidity seems to be a major concern of all B-PT-B graft techniques. It include complications such as damaging the knee estensor apparatus, the potential for subsequent patello-femoral joint pain or crepitation, patella fracture, patella tendon rupture, infra-patella contraction, numbness caused by damage of the infra-patellar branch of the saphenous nerve and possible loss of quadriceps strenght [14,28,31]. We reported anterior algodystrophy (patello-femoral pain and numbness) as the second major complication, observed in 17% of patients in group A and 13% of patients in group B.
Our results are similar to those reported in the literature and prove that femoral press-fit fixation has the same efficacy of screw fixation but avoids all disadvantages of hardware. The main limitation of our study is the presence of two different rehabilitative protocols that may be a bias and could negatively affect our statistical results.
We concluded that femoral press-fit fixation of B-PT-B autograft during ACL reconstruction is an efficient procedure. It provides stable fixation at low cost, it ensures unlimited bone-to-bone healing and high primary stability, avoiding the disadvantages of hardware fixation and the need for removal in case of revision. It is a technically high demanging procedure and it should be avoided in patient with poor bone quality and with pre-existing patello-femoral problems.
1. Aglietti P, Buzzi R, D’Andria S, Zaccherotti G. Long-term study of anterior cruciate ligament reconstruction for chronic instability using the central one-third patellar tendon and a lateral extraarticular tenodesis. Am J Sports Med. 1992 Jan-Feb;20(1):38-45.
2. Aglietti P, Buzzi R, Giron F, Simeone AJ, Zaccherotti G. Arthroscopic-assisted anterior cruciate ligament reconstruction with the central third patellar tendon. A 5-8-year follow-up. Knee Surg Sports Traumatol Arthrosc. 1997;5(3):138-44.
3. Al-Husseiny M, Batterjee K. Press-fit fixation in reconstruction of anterior cruciate ligament, using bone-patellar tendon-bone graft. Knee Surg Sports Traumatol Arthrosc. 2004 Mar;12(2):104-9.
4. Boszotta H. Arthroscopic anterior cruciate ligament reconstruction using a patellar tendon graft in press-fit technique: surgical technique and follow-up. Arthroscopy. 1997 Jun;13(3):332-9.
5. Brand J Jr, Weiler A, Caborn DN, Brown CH Jr, Johnson DL. Graft fixation in cruciate ligament reconstruction. Am J Sports Med. 2000 Sep-Oct;28(5):761-74.
6. Brown GA, Peña F, Grøntvedt T, Labadie D, Engebretsen L. Fixation strength of interference screw fixation in bovine, young human, and elderly human cadaver knees: influence of insertion torque, tunnel-bone block gap, and interference. Knee Surg Sports Traumatol Arthrosc. 1996;3(4):238-44.
7. Felmet G. Implant-free press-fit fixation for bone-patellar tendon-bone ACL reconstruction: 10-year results. Arch Orthop Trauma Surg. 2010 Aug;130(8):985-92. doi: 10.1007/s00402-010-1050-2.
8. Gobbi A, Diara A, Mahajan S, Zanazzo M, Tuy B. Patellar tendon anterior cruciate ligament reconstruction with conical press-fit femoral fixation: 5-year results in athletes population. Knee Surg Sports Traumatol Arthrosc. 2002 Mar;10(2):73-9.
9. Harner CD, Marks PH, Fu FH, Irrgang JJ, Silby MB, Mengato R. Anterior cruciate ligament reconstruction: endoscopic versus two-incision technique. Arthroscopy. 1994 Oct;10(5):502-12.
10. Hertel P (1990) Anatomic reconstruction of the ACL: a new techinique for ACL replacement. Presented at the 4th ESSKA congress, Stockholm.
11. Hertel P, Behrend H, Cierpinski T, Musahl V, Widjaja G. ACL reconstruction using bone-patellar tendon-bone press-fit fixation: 10-year clinical results. Knee Surg Sports Traumatol Arthrosc. 2005 May;13(4):248-55.
12. Irrgang JJ, Ho H, Harner CD, Fu FH. Use of the International Knee Documentation Committee guidelines to assess outcome following anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 1998;6(2):107-14.
13. Jagodzinski M, Scheunemann K, Knobloch K, Albrecht K, Krettek C, Hurschler C et al. Tibial press-fit fixation of the hamstring tendons for ACL-reconstruction. Knee Surg Sports Traumatol Arthrosc. 2006 Dec;14(12):1281-7.
14. Järvelä T, Paakkala T, Kannus P, Järvinen M. The incidence of patellofemoral osteoarthritis and associated findings 7 years after anterior cruciate ligament reconstruction with a bone-patellar tendon-bone autograft. Am J Sports Med. 2001 Jan-Feb;29(1):18-24.
15. Kurosaka M, Yoshiya S, Andrish JT. A biomechanical comparison of different surgical techniques of graft fixation in anterior cruciate ligament reconstruction. Am J Sports Med. 1987 May-Jun;15(3):225-9.
16. Loubignac F, Lecuire F, Rubini J, Basso M. Troublesome radiologic changes after reconstructive fixation of the anterior cruciate ligament with resorbable interference screws. Acta Orthop Belg. 1998 Mar;64(1):47-51.
17. Malek MM, DeLuca VJ, Verch DV: “Arthroscopically Assisted Anterior Cruciate Ligament Reconstruction using Central Third Patellar Tendon Autograft with Press-Fit femoral fixation” Current Techniques in Artroscopy 1995; Chapter 15;159-168.
18. Martinek V, Friederich NF. Tibial and pretibial cyst formation after anterior cruciate ligament reconstruction with bioabsorbable interference screw fixation. Arthroscopy. 1999 Apr;15(3):317-20.
19. Musahl V, Abramowitch SD, Gabriel MT, Debski RE, Hertel P, Fu FH et al. Tensile properties of an anterior cruciate ligament graft after bone-patellar tendon-bone press-fit fixation. Knee Surg Sports Traumatol Arthrosc. 2003 Mar;11(2):68-74.
20. O’Brien SJ, Warren RF, Pavlov H, Panariello R, Wickiewicz TL. Reconstruction of the chronically insufficient anterior cruciate ligament with the central third of the patellar ligament. J Bone Joint Surg Am. 1991 Feb;73(2):278-86.
21. Paessler HH, Mastrokalos DS. Anterior cruciate ligament reconstruction using semitendinosus and gracilis tendons, bone patellar tendon, or quadriceps tendon-graft with press-fit fixation without hardware. A new and innovative procedure. Orthop Clin North Am. 2003 Jan;34(1):49-64.
22. Papageorgiou CD, Ma CB, Abramowitch SD, Clineff TD, Woo SL. A multidisciplinary study of the healing of an intraarticular anterior cruciate ligament graft in a goat model. Am J Sports Med. 2001 Sep-Oct;29(5):620-6.
23. Patel JV, Church JS, Hall AJ. Central third bone-patellar tendon-bone anterior cruciate ligament reconstruction: a 5-year follow-up. Arthroscopy. 2000 Jan-Feb;16(1):67-70.
24. Pavlik A, Hidas P, Czigány T, Berkes I. Biomechanical evaluation of press-fit femoral fixation technique in ACL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2004 Nov;12(6):528-33.
25. Pavlik A, Hidas P, Tállay A, Toman J, Berkes I. Femoral press-fit fixation technique in anterior cruciate ligament reconstruction using bone-patellar tendon-bone graft: a prospective clinical evaluation of 285 patients. Am J Sports Med. 2006 Feb;34(2):220-5.
26. Rupp S, Krauss PW, Fritsch EW. Fixation strength of a biodegradable interference screw and a press-fit technique in anterior cruciate ligament reconstruction with a BPTB graft. Arthroscopy. 1997 Feb;13(1):61-5.
27. Said HG, Baloch K, Green M. A new technique for femoral and tibial tunnel bone grafting using the OATS harvesters in revision anterior cruciate ligament reconstruction. Arthroscopy. 2006 Jul;22(7):796.
28. Salmon LJ, Russell VJ, Refshauge K, Kader D, Connolly C, Linklater J et al. Long-term outcome of endoscopic anterior cruciate ligament reconstruction with patellar tendon autograft: minimum 13-year review. Am J Sports Med. 2006 May;34(5):721-32.
29. Sarzaeem MM, Najafi F, Razi M, Najafi MA. ACL reconstruction using bone-patella tendon-bone autograft: press-fit technique vs. interference screw fixation. Arch Orthop Trauma Surg. 2014 Jul;134(7):955-62. doi: 10.1007/s00402-014-1999-3.
30. Schmidt-Wiethoff R, Dargel J, Gerstner M, Schneider T, Koebke J. Bone plug length and loading angle determine the primary stability of patellar tendon-bone grafts in press-fit ACL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2006 Feb;14(2):108-11.
31. Shelbourne KD, Gray T. Minimum 10-year results after anterior cruciate ligament reconstruction: how the loss of normal knee motion compounds other factors related to the development of osteoarthritis after surgery. Am J Sports Med. 2009 Mar;37(3):471-80. doi: 10.1177/0363546508326709.
32. Shelbourne KD, Nitz P. Accelerated rehabilitation after anterior cruciate ligament reconstruction. Am J Sports Med. 1990 May-Jun;18(3):292-9.
33. Widuchowski W, Widuchowska M, Koczy B, Dragan S, Czamara A, Tomaszewski W et al. Femoral press-fit fixation in ACL reconstruction using bone-patellar tendon-bone autograft: results at 15 years follow-up. BMC Musculoskelet Disord. 2012 Jun 27;13:115. doi: 10.1186/1471-2474-13-115.
Table 1. IKDC results between the two groups (p=0,002).
Table 2. Side-to-side difference with arthrometer (p=0,002).
|Side-to-side difference with KT-1000||Kurosaka||Press-fit|
|> 10 mm||0%||0%|
Table 3. Overall complications (p=0,4).
|Extension gap >10°||0%||0%|
|Flexion gap <10°||2%||4%|
|Interference screw problems||4%||0%|