Femoral fixation of hamstring grafts in posterior cruciate ligament reconstruction: biomechanical evaluation of different fixation techniques: is there an acute angle effect?

BACKGROUND: The literature provides little biomechanical data about femoral fixation of hamstring grafts in posterior cruciate ligament reconstruction. HYPOTHESIS: A hybrid fixation technique with use of an undersized screw has sufficient strength to provide secure fixation of posterior cruciate ligament grafts. Additional aperture fixation with a biodegradable interference screw can prevent graft damage that might be caused by an acute angle on the edge of the femoral tunnel. STUDY DESIGN: Controlled laboratory study. METHODS: In part 1, extracortical fixation of posterior cruciate ligament reconstructions with quadrupled porcine flexor digitorum grafts to simulate human hamstring grafts was compared with hybrid fixation methods using 6-, 7-, and 8-mm screws. Groups were tested in cycling loading with the load applied in line with the bone tunnel. In part 2, extracortical fixation was compared with hybrid fixation using a 1-mm undersized screw anterior and posterior to the graft. Structural properties and graft abrasion were evaluated after cyclic loading with the load applied at 90 degrees to the tunnel. In each group, 8 porcine knees were tested. RESULTS: In part 1, stiffness, maximum load, and yield load were significantly higher for hybrid fixation than for extracortical fixation. Hybrid fixation with an 8-mm screw resulted in higher yield load than with a 7-mm screw. In part 2, graft laceration was more pronounced in specimens with extracortical fixation than with hybrid fixation. Posterior screw placement was superior to the anterior position. CONCLUSION: For all parameters, hybrid fixation with an interference screw provided superior structural results. No relevant disadvantages of undersized screws could be found. Graft damage due to abrasion at the edge of the femoral bone tunnel was reduced by use of an interference screw. The posterior screw placement seems favorable. CLINICAL RELEVANCE: Hybrid fixation of hamstring grafts in posterior cruciate ligament reconstruction is superior to extracortical fixation alone with no relevant disadvantages of undersized screws. The results raise the suspicion of an acute angle effect of the femoral bone tunnel.     

A new bicortical tibial fixation technique in anterior cruciate ligament reconstruction with quadruple hamstring graft

We report a prospective series of 101 patients receiving a four-strand semitendinosus-gracilis autograft for anterior cruciate ligament reconstruction using a new bicortical tibial fixation technique with bioabsorbable interference screws. Patients (average age 32 years) were operated on between November 1997 and Mai 1998, and follow-up was at least 12 months postoperatively. The evaluation consisted of history, clinical examination, IKDC score, Cincinnati Knee Score, KT-1000 testing, standardized radiography and magnetic resonance imaging. One hundred patients were available for follow-up. There were two traumatic reruptures 6 and 11 months postoperatively. By IKDC score 87 patients were in groups A and B, 12 in group C, and 2 with a rerupture in group D. Mean Cincinnati Knee Score was 82 (range 46–100), KT-1000 manual maximum at follow-up showed an average difference of 1.7 mm between the sides. Full extension was rapidly achieved in all cases, and flexion averaged 135°. Considering the enlargement caused by the bioabsorbable interference screws, the incidence of tunnel widening was 6.6% on the femoral side and 1.7% on the tibial side. Tunnel widening did not affect the clinical results. Three patients experienced an effusion after more than 6 months postoperatively. There was one infection, which settled without functional impairment after early arthroscopic lavage and intravenous antibiotics. Otherwise no complications occurred. The described technique for anterior cruciate ligament reconstruction combines the advantage of anatomical graft position with sufficient graft fixation. A short intra-articular graft construct with a strong tendon to bone interface was created. Clinically, 87% of patients had a normal or nearly normal IKDC score at follow-up. Magnetic resonance imaging revealed a considerable increase in tunnel area caused by the insertion of the interference screws. On the other hand, the development of a “fibrous interzone” between the graft and the bone tunnel was prevented in most cases. At short-term follow-up the bicortical tibial fixation proved to be efficient even with an aggressive rehabilitation program. Received: 26 November 1999 Accepted: 5 March 2000     

Bone tunnel enlargement following anterior cruciate ligament reconstruction: a randomised comparison of hamstring and patellar tendon grafts with 2-year follow-up

Radiographic tibial and femoral bone tunnel enlargement has been demonstrated following anterior cruciate ligament (ACL) reconstruction. This study investigated whether bone tunnel enlargement differs between four-strand hamstring (HS) and patellar tendon (PT) ACL reconstructions over the course of a 2-year follow-up. Patients undergoing primary ACL reconstruction (n = 65) were randomised to receive either a PT or HS autograft. Femoral fixation in both groups was by means of an Endobutton. On the tibial side the PT grafts were fixed using a metallic interference screw, and the HS tendons by sutures tied to a fixation post. The PT grafts were inserted such that the proximal end of the distal bone block was within 10 mm of the tibial articular surface, resulting in a portion of free patellar tendon in the femoral tunnel immediately proximal to the articular surface. Patients were reviewed after 4 months and 1 and 2 years. Tunnel enlargement was determined by measuring the widths of the femoral and tibial tunnels with a digital caliper in both lateral and anteroposterior radiographs. Because of the presence of the interference screw and the proximity of the bone block to the tibial articular surface, the tibial tunnel could not be reliably measured in the PT group. Measurements were corrected for magnification, and changes in tunnel width were recorded relative to the diameters drilled at surgery. Standard clinical measures were also noted. In 32% of patients in the PT group there was femoral tunnel obliteration from 4 months onwards. For the other patients there was a significantly greater increase in femoral tunnel width in the HS group than in the PT group at each follow-up, but no significant change with time. There was also a marked increase in tibial tunnel width in the HS group at 4 months but not thereafter. There was no relationship between tunnel enlargement and clinical measurements. Although tunnel enlargement is more common and greater with HS grafts, it does not appear to affect the clinical outcome in the first 2 postoperative years. Femoral suspensory fixation does not in itself appear to be the principal cause of femoral tunnel enlargement, at least for PT grafts.     

Bone tunnel enlargement after anterior cruciate ligament reconstruction using hamstring tendons

We retrospectively reviewed 87 anterior cruciate ligament reconstructions using autogenous hamstring tendons with the Endobutton technique to investigate the relationship between bone tunnel enlargement and clinical outcome and to identify factors that contribute to the enlargement. The clinical outcome was evaluated using the Lysholm score and KT-1000 arthrometer. The location of the femoral tunnel with respect to Blumensaat's line, the tibial tunnel with respect to the tibial plateau, and the angle between the femoral tunnel and Blumensaat's line (femoral tunnel angle) were measured. Bone tunnel enlargement was observed in 32 patients (37%). Enlargement occurred in 22 of the femoral tunnels and 26 of the tibial tunnels. Enlargement of both tunnels occurred in 16 knees. There was no statistical difference in Lysholm scores or KT-1000 arthrometer measurements between the enlarged group and the unenlarged group. The femoral tunnel was placed more anteriorly in the enlarged femoral tunnel group than in the unenlarged femoral tunnel group. The tibial tunnel was placed more anteriorly in the enlarged tibial tunnel group than in the unenlarged tibial tunnel group. The femoral tunnel angle was significantly smaller in the enlarged femoral tunnel group than in the femoral unenlarged group. Gender, patient age, intraoperative isometricity, and graft size were not significant factors. Bone tunnel enlargement was not correlated with the clinical outcome measures. We conclude that the main factor associated with tunnel enlargement are the locations and angles of the tunnels. The windshield-wiper motion of the graft may be enhanced by changing tension in the graft due to tunnel malposition. An acute femoral tunnel angle may increase the mechanical stress on the anterior margin of the femoral tunnel.     

Tibial bone bridge and bone block fixation in double-bundle anterior cruciate ligament reconstruction without hardware: a technical note

Current techniques for tibial graft fixation in four tunnels double bundle (DB) anterior cruciate ligament (ACL) reconstruction are by means of two interference screws or by extracortical fixation with a variety of different implants. We introduce a new alternative tibial graft fixation technique for four tunnels DB ACL reconstruction without hardware. About 3.5 to 5.5 cm bone cylinder with a diameter of 7 mm is harvested from the anteromedial (and posterolateral) tibial bone tunnel (s) with a core reamer. The anteromedial (AM) and posterolateral (PL) hamstring tendon grafts (or alternatively tendon allografts) are looped over an extracortical femoral fixation device and cut in length according to the total femorotibial bone tunnel length. The distal 3 cm of each, the AM- and PL bundle graft are armed with two strong No. 2 nonresorbable sutures and the four suture ends of each graft are tied to each other over the 2 cm wide cortical bone bridge between the tibial AM and PL bone tunnel. In addition the AM- and/or PL bone block which was harvested at the beginning of the procedure is re-impacted into the two tibial bone tunnels. A dorsal splint is used for the first two postoperative weeks and physiotherapy is started the second postoperative day. The technique is applicable for four tunnels DB ACL reconstruction in patients with good tibial bone quality. The strong fixation technique preserves important tibial bone stock and avoids the use of tibial hardware which knows disadvantages. It does increase tendon to bone contact and tendon-to-bone healing and does reduce implant costs to those of a single bundle (SB) ACL reconstruction. Revision surgery may be facilitated significantly but the technique should not be used when bony defects are present. In case of insufficient bone bridge fixation or bone blocks hardware fixation can be applied as usual. Not supported by outside funding or grant(s): No benefits in any form have been received, or will be received, from a commercial party related directly or indirectly to the subject of this article. The study complies with the current laws of the country, in which it was performed.     

Comparison of three techniques of anterior cruciate ligament reconstruction with bone-patellar tendon-bone graft. Differences in anterior tibial translation and tunnel enlargement with each technique

BACKGROUND: Anatomic fixation of the graft in anterior cruciate ligament reconstruction has improved stability of the reconstructed knee joint in experimental studies. HYPOTHESIS: Anatomic fixation of the bone-patellar tendon-bone autograft will reduce tunnel enlargement and improve clinical results. STUDY DESIGN: Prospective cohort study. METHODS: Sixty patients were randomly divided into three groups: a nonanatomic fixation group (traditional single-incision reconstruction), an anatomic fixation group (reconstruction in which a bone plug was grafted into the tibial tunnel), and an anatomic fixation group with all-inside reconstruction. Stability of the knee joint was examined with a KT-1000 arthrometer at 2, 4, 6, 12, and 24 months after surgery. At 12 months, anteroposterior and lateral radiographs were made to assess tunnel enlargement. RESULTS: Although the magnitude of tibial displacement gradually increased after reconstruction in all three groups, the anatomic fixation group had significantly better stability than the groups undergoing nonanatomic fixation or all-inside anatomic fixation at 4 and 6 months after anterior cruciate ligament reconstruction. However, there was no significant difference between the three groups at 24 months. Regarding the tibial tunnel, residual rates and enlargement of tunnels were different between the reconstruction techniques. The nonanatomic reconstruction group had significantly greater tunnel enlargement. CONCLUSION: Anatomic fixation of the graft decreased the tunnel enlargement but had no effect on knee stability at 2-year follow-up.     

Tunnel widening following anterior cruciate ligament reconstruction using hamstring autograft: a comparison between double cross-pin and suspensory graft fixation

Femoral and tibial tunnel widening following ACL reconstruction using hamstring autograft has been described. Greater tunnel widening has been reported with suspensory fixation systems. We hypothesized that greater tunnel widening will be observed in patients whose hamstring autograft was fixated using a cortical, suspensory system, compared to double cross-pin fixation on the femur. We performed clinical and radiographic evaluation on 46 patients at minimum 2 years after primary ACL reconstruction. We measured subjective and objective outcomes including KT-1000 and AP, lateral radiographs. A musculoskeletal radiologist, independent of the surgical team, measured tunnel width, while correcting for magnification, at the widest point and at 1 cm away from tibial and femoral tunnel apertures. Patients in the suspensory graft fixation group exhibited significantly greater absolute change and greater percent change in femoral tunnel diameter compared to patients with double cross-pin fixation (P ≤ 0.05). This difference was noted on both AP and lateral radiographs and at both measurement sites. There was no significant difference between groups for tibial tunnel widening, IKDC subjective scores or KT-1000 side to side differences. There was significantly more femoral tunnel widening associated with the use of the endobutton suspensory fixation system compared to the use of double cross-pins for fixation within the tunnel.     

Augmentation of femoral fixation in hamstring anterior cruciate ligament reconstruction with a bioabsorbable bead: a prospective single-blind randomized clinical trial

BACKGROUND: The EndoPearl is an adjunct to bioabsorbable interference screw fixation in the femoral tunnel in anterior cruciate ligament (ACL) reconstruction. The purpose of the study was to assess the clinical effectiveness of the EndoPearl using the KT-1000 Knee Arthrometer and the Mohtadi ACL Quality of Life (ACL-QOL) Questionnaire. HYPOTHESIS: The application of the EndoPearl in hamstring ACL reconstruction has no significant benefit when compared to conventional treatment in KT-1000 and ACL-QOL Questionnaire outcomes. STUDY DESIGN: Prospective single-blind randomized clinical trial. METHODS: ACL reconstruction with autogenous semitendinosus and gracilis tendons was performed on 35 patients. Preoperatively, 3 months, 6 months, and 18 months postoperatively, patients' knees were evaluated using the KT-1000 Knee Arthrometer and the ACL-QOL Questionnaire. RESULTS: Statistically significant differences were achieved in terms of KT-1000 side-to-side differences between the study group and the control group at 6 months and 18 months postoperatively; the mean side-to-side differences are significantly less in the study group when compared to the control group. Statistically significant differences were not detected when comparing the ACL-QOL Questionnaire between the two groups at all time intervals. CONCLUSION: The application of the EndoPearl in conjunction with a bioscrew in the femoral tunnel in autogenous ACL reconstruction using semitendinosus and gracilis tendon grafts provides a significantly decreased laxity up to 18 months postoperatively in terms of KT-1000 side-to-side differences.     

The role of periosteal flap in the prevention of femoral widening in anterior cruciate ligament reconstruction using hamstring tendons

Tunnel widening in anterior cruciate ligament reconstruction has been reported for many years, whatever the type of plasty (allo- or autograft) or graft (patellar or hamstring tendons). Recently, the hypothesis has been formulated that widening would be responsible for later laxity of the knees. Micromobility of the graft or biological factors are classically responsible for the enlargement. In order to improve the biological conditions around the graft within the tunnel, we have developed a surgical technique using a periosteal flap. The periosteal flap is harvested at the superior and medial metaphysis of the tibia and wrapped around the proximal part of the four strands of gracilis and semitendinosus tendons near the outlet of the femoral tunnel. Forty-one patients with isolated rupture of the ACL were included in a prospective and randomized study: the first group of 20 patients had femoral fixation by Transfix and resorbable screw, the second group of 21 patients had femoral fixation by Transfix and periosteal flap. The diameters of the tunnel were measured between the sclerotic margins at the tunnel entrance and 1 cm above, and compared to the peroperative drill size. The percentage change in diameter was calculated as: (tunnel diameter–drill size)/drill size. The two groups of patients were comparable as to gender, side, age, KT-1000 side to side difference, femoral tunnel diameter and follow-up. At 2.5 months and 11 months postoperatively on average, there was a significant reduction of enlargement at the outlet of the tunnel with the use of a periosteal flap but widening was constant.     

Tibial tunnel widening after anterior cruciate ligament reconstructions with hamstring tendons using Rigidfix femoral fixation and Intrafix tibial fixation

The purpose of this study was to evaluate tibial tunnel widening prospectively after anterior cruciate ligament (ACL) reconstruction with hamstring tendon grafts using Rigidfix (DePuy Mitek, Raynham, MA) femoral fixation and Intrafix (DePuy Mitek) tibial fixation. Fifty-six consecutive patients who underwent ACL reconstruction with a minimum of 2 years’ postoperative evaluation were reviewed. On the anterior–posterior (AP) and lateral radiographs, the diameter of the tibial tunnel was measured at proximal, middle, and distal positions, and the shape of the tibial tunnels were classified. Tunnel widening was defined as widening of greater than 2 mm. Group I was defined as cases with no tunnel widening, and group II was defined as cases with tunnel widening. Postoperative laxity evaluations were performed using Lachman test, pivot-shift test, and instrumented laxity testing using the KT-1000 arthrometer. On the AP radiographs, the average diameter of the tibial tunnel increased 8.8% at 6 months and 8.5% at 12 months postoperatively compared to the immediate postoperative day. On the lateral radiographs, the average diameter of the tibial tunnel increased 7.2% at 6 months and 8.1% at 12 months year postoperatively compared to the immediate postoperative day. The tunnel shape evaluation revealed predominantly linear type in 53 patients (95%). Group I was 42 patients (75%), and group II was 14 (25%). The average KT-1000 measurement was 1.0 ± 1.8 mm in group I and 2.1 ± 2.8 mm in group II (n.s.). The Lachman and pivot-shift tests showed no significant differences between the two groups. In conclusion, hamstring ACL reconstruction using Rigidfix and Intrafix fixation showed less widening of the tibial tunnels than observed in previously published studies.     

Tunnel expansion following anterior cruciate ligament reconstruction: a comparison of hamstring and patellar tendon autografts

Thirty patients having had anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone (BPTB) autograft and thirty patients having had ACL reconstruction with hamstring (HS) autograft were enrolled. All procedures were performed using an endoscopic technique with identical postoperative rehabilitation, such that the only variable was the type of graft and its fixation. Lateral and 45° posteroanterior (PA) weightbearing radiographs were performed in each patient at 6–12 (mean 9) months postoperatively in the HS group and 9–22 (mean 13) months postoperatively in the PT group. The sclerotic margins of the tunnel were measured at the widest dimension of the tunnel by a single observer and were compared with the initially drilled tunnel size after correction for radiographic magnification. For the BPTB group, all bone plugs appeared to be incorporated radiographically. On the femoral side, the bone plug was incorporated at the roof of the intercondylar notch, such that no tunnel measurement could be made. Well-defined sclerotic margins were always present at the tibial and femoral tunnels for the HS group and at the tibial tunnel for the BPTB group. The mean percentage increase in tunnel size in the PA view was 9.7% ± 14.7% for the BPTB tibial tunnel, 20.9% ± 13.4% for the HS tibial tunnel, and 30.2% ± 17.2% for the HS femoral tunnel. The mean percentage increase in tunnel size in the lateral view was 14.4% ± 16.1% for the BPTB tibial tunnel, 25.5% ± 16.7% for the HS tibial tunnel, and 28.1% ± 14.7% for the HS femoral tunnel. The difference in HS and BPTB tibial tunnel expansion on both the PA and lateral views was statistically significant (P = 0.003 and P = 0.01, respectively). Inter-observer variability was excellent with an intra-class correlation coefficient of 0.92. Tunnel expansion was significantly greater following ACL reconstruction using HS autografts than in those using BPTB autografts. The points of fixation for the HS grafts are at a greater distance from the normal insertion site and biomechanical point of action of the ACL than the points of fixation for BPTB grafts. We believe that this greater distance creates a potentially larger force moment during graft cycling which may lead to greater expansion of bone tunnels. Received: 17 March 1997 Accepted: 30 June 1997     

Comparison of eccentric and concentric screw placement for hamstring graft fixation in the tibial tunnel

Interference screw fixation of four-strand hamstring grafts for ACL reconstruction has recently been introduced. By this method, the interference screw is placed in the tibial and femoral tunnels eccentric (adjacent) to the bundled limbs of the graft. In order to maximize the graft to tunnel contact to promote ¶biological fixation, it is proposed to place the screw concentrically in ¶the tunnel, in the middle of the four limbs of the graft, pressing each limb of the graft into the tunnel wall. This would be difficult to do in the proximal, folded end of the four limb graft situated in the femoral tunnel but can be done easily in the tibial tunnel. The purpose of this study was to evaluate the effect of screw placement on the stiffness, yield load, and ultimate load of hamstring graft fixation in the tibial tunnel. Five pairs of human knees were ¶used for the study. Pull out tests ¶were performed using an MTS system, pulling along the axis of the ¶tibial tunnel. Tibial fixation stiffness was greater using concentric screw placement (P < 0.05) although there was no statistical difference in yield load, slippage, or ultimate load.     

The effect of remnant preservation on tibial tunnel enlargement in ACL reconstruction with hamstring autograft: a prospective randomized controlled trial

Purpose

To investigate the effect of remnant preservation on tibial tunnel enlargement in a single-bundle anterior cruciate ligament (ACL) reconstruction with a hamstring autograft.

Methods

From 2006 to 2009, a total of 62 patients who underwent single-bundle ACL reconstruction with a quadrupled hamstring tendon autograft were enrolled in this study. The patients were randomly divided into two groups: the preserving-remnant group and the removing-remnant group. Plain radiographs were taken at 1 week, and 3, 6, and 24 months postoperatively, and tibial tunnel enlargement was evaluated. The postoperative clinical assessment included the Lysholm rating scale and KT-1000 measurement.

Results

In total, 27 patients in the preserving-remnant group and 24 patients in the removing-remnant group were followed up and the median follow-up was 24.5 months (range 24–27 months). Tibial tunnel enlargement occurred within 6 months postoperatively. Positive enlargement was observed in 8 patients (29.6 %) in the preserving-remnant group and 14 patients (58.3 %) in the removing-remnant group (P = 0.0388). The percentage of tibial tunnel enlargement was 25.7 ± 6.7 and 34.0 ± 8.9 % in the preserving- and removing-remnant groups, respectively (P = 0.0004). In the preserving-remnant group, the average Lysholm score increased from 60.3 ± 5.3 (51–69) to 93.0 ± 3.5 (88–100), and the side-to-side difference of the KT-1000 changed from 6.3 ± 0.9 (5.1–8.0) to 1.4 ± 0.6 (0.5–2.4) mm. In the removing-remnant group, the average Lysholm score increased from 58.7 ± 6.5 (48–71) to 91.1 ± 3.9 (85–100), and the side-to-side difference of the KT-1000 changed from 6.5 ± 0.8 (5.4–8.2) to 1.7 ± 0.6 (0.6–2.8) mm.

Conclusions

It is confirmed that remnant preservation in ACL reconstruction can resist tibial tunnel enlargement but that this technique does not affect the short-term clinical outcome of ACL reconstruction.

Level of evidence

I.     

Arthroscopic anterior cruciate ligament double-bundle reconstruction using hamstring tendon grafts-fixation with two interference screws: technical note

In this article, an original double-bundle anterior cruciate ligament reconstruction technique is described. The procedure is developed using hamstring tendon grafts while maintaining tibial osseous insertion. Two tibial tunnels are drilled and a simplified and precise outside-in double tunnel femoral drilling technique is utilized. The graft fixation is made using only two interference screws.     

Close-looped graft suturing improves mechanical properties of interference screw fixation in ACL reconstruction

Purpose

In anterior cruciate ligament reconstruction with looped soft-tissue grafts, an interference screw is frequently used for tibial fixation. This study compared three alternatives thought to improve the initial mechanical properties of direct bioabsorbable interference screw fixation: suturing the graft to close the loop, adding a supplementary staple, or increasing the oversize of the screw diameter relative to the bone tunnel from 1 to 2 mm.

Methods

Twenty-eight porcine tibiae and porcine flexor digitorum profundus tendons were randomized into four testing groups: a base fixation using 10-mm-diameter screw with open-looped graft, base fixation supplemented by an extracortical staple, base fixation but closing the looped graft by suturing its ends, and base fixation but using an 11-mm screw. Graft and bone tunnel diameters were 9 mm in all specimens. Constructs were subjected to cyclic tensile load and finally pulled to failure to determine their structural properties.

Results

The main mode of failure in all groups was pull-out of tendon strands after slippage past the screw. The sutured graft group displayed significantly lower residual displacement (mean value reduction: 47–67 %) and higher yield load (mean value increase: 38–54 %) than any alternative tested. No other statistical differences were found.

Conclusions

Suturing a soft-tissue graft to form a closed loop enhanced the initial mechanical properties of tibial fixation with a bioabsorbable interference screw in anterior cruciate ligament reconstructions using a porcine model, and thus, this may be an efficient means to help in reducing post-operative laxity and early clinical failure. No mechanical improvement was observed for an open-looped tendon graft by adding an extracortical staple to supplement the screw fixation or by increasing the oversize of the screw to tunnel diameter from 1 to 2 mm.     

Comparison of the bioabsorbable and metal screw fixation after ACL reconstruction with a hamstring autograft in MRI and clinical outcome: a prospective randomized study

There has never been an MRI study of tunnel widening comparing bioabsorbable to metal screw fixation in autologous hamstring anterior cruciate ligament (ACL) reconstruction. We randomized 62 patients to hamstring ACL reconstruction with either a bioabsorbable (n = 31) or metal screw (n = 31) fixation. The evaluation methods were clinical examination, KT-1000 arthrometric measurement, the International Knee Documentation Committee and Lysholm scores, and MRI. There were no differences between the groups preoperatively. Fifty-five patients (89%) were available at a minimum of 2-year follow-up (range 24–36 months). There was tunnel widening in both groups, but the increase was significantly greater in the AP dimension of the femoral tunnel in the bioabsorbable screw group compared to metal group (P = 0.01). The tibial tunnels showed no intergroup difference. Ninety-four percent of the knees were normal or nearly normal according to the IKDC scores and the average Lysholm score was 91 with no intergroup difference. The follow-up AP tibial tunnel diameter was smaller with normal knee laxity compared to abnormal knee laxity. The graft failure rate in the bioabsorbable screw group was 23% (7/31 patients) and 6% (2/31 patients) in the metal screw group. The use of bioabsorbable screws resulted in more femoral tunnel widening, and more graft failures compared to metal screws. The tunnel widening in the tibia was associated with the knee laxity (P = 0.02).     

Arthroscopic anterior cruciate ligament reconstruction with periosteum-enveloping hamstring tendon graft

Tendon–bone incorporation of a tendon graft within the bone tunnel is of priority concern when using for anterior cruciate ligament (ACL) reconstruction. Superior healing process and stronger healing strength can be achieved when periosteum is sutured on the tendon inserted into a bone tunnel. We applied this idea to ACL reconstruction for enhancing tendon graft–bone tunnel healing. This is a prospective clinical outcome study with this surgical technique at minimal 2 years follow-up. Periosteum-enveloping hamstring tendon graft has been used in 68 patients. Data from 62 patients who had been followed up completely were analyzed. All patients suffered from a grade 3 or higher grade of Lachman and anterior drawer test with a positive pivot-shift test. Clinical assessments included the Lysholm knee scores, International Knee Documentation Committee (IKDC) scores, KT-1000 instrumented testing, thigh muscle assessment, and radiographic evaluation. The median Lysholm knee score was 59 (40–70) and 94 (60–100) points (P<0.01) before and after surgery. After reconstruction, 81% of patients were able to return to moderate or strenuous activity. Four (6%) patients were found to exhibit grade 2 or more ligament laxity. Complete range of motion could be achieved in 86% of patients. Three patients (5%) had positive pivot shift. Finally, 92% of patients were assessed as normal or nearly normal rating by IKDC guideline. Bone tunnels enlargement of more than 1 mm was identified in 5% of femoral tunnels and 6% of tibial tunnels. The study shows that a satisfactory result can be achieved with the periosteum-enveloping hamstring tendon graft in ACL reconstruction. Periosteum can be easily harvested at the proximal tibia from a routine incision for hamstring tendon harvesting. Besides the potential for improving tendon–bone healing, enveloped periosteum may help to seal the intra-articular tunnel opening in the early postoperative period, and thus avoid synovial fluid reflux into the tunnel. Bone tunnel enlargement could be reduced.     

Placement of femoral tunnel between the AM and PL bundles using a transtibial technique in single-bundle ACL reconstruction

Tunnel enlargement after anterior cruciate ligament (ACL) reconstruction may compromise revision surgery. The cause of this tunnel enlargement is not yet fully understood, but it is thought to be multifactorial, with biomechanical and biological factors playing a role. Tunnel enlargement has been described particularly in patients who underwent ACL reconstruction with hamstring tendons with extracortical fixation devices. The purpose of our study was to evaluate prospectively with magnetic resonance imaging (MRI) the changes in femoral tunnel diameter following arthroscopic anatomic ACL reconstruction with hamstring tendons. At 3-month post-op, all tunnels had enlarged compared to the diameter of the drill and most tunnels enlarged more in the midsection than at the aperture. In the posterolateral tunnels, the entrance increased 16% in diameter and the middle of the tunnel increased 30% in diameter. In the anteromedial femoral tunnels, the tunnels enlarged 14% at the aperture and 35% in the midsection. All femoral tunnels enlarged and most of them enlarged in a fusiform manner. The biological factors explain better our findings than the mechanical theory, although mechanical factors may play a role and the cortical bone at the entrance of the tunnel may modify the way tunnels respond to mechanical stress.     

Tunnel widening in anterior cruciate ligament reconstruction: a prospective evaluation of hamstring and patella tendon grafts

We report a prospective series evaluating the incidence and degree of tunnel widening in a well-matched series of patients receiving a hamstring or patella tendon graft for anterior cruciate ligament (ACL) deficiency. We correlated tunnel widening with clinical factors, knee scores, KT-1000 and isokinetic muscle strength to determine the clinical significance of this finding. Seventy-three patients at least 12 months post-ACL reconstruction were evaluated. Thirty-eight patients had received a doubled semitendinous and gracilis graft and 35 a bone-patella tendon-bone graft. All patients underwent a similar endoscopic procedure and accelerated postoperative rehabilitation. Tunnel widening was determined using standardized anteroposterior (AP) and lateral X-rays adjusted for magnification. A limited series of MRIs was performed to validate these measurements. There was a significant difference in the degree of tunnel widening between the two groups. The mean increase in femoral tunnel area in the hamstring group was 100.4% compared with a decrease of 25% in the patella tendon group (P = < 0.0001). In the tibial tunnel the mean increase in the hamstring group was 73.9% compared with a decrease of 2.1% in the patella tendon group (P = < 0.0001). The MRIs validated the plain film measurements. Tunnel widening did not correlate with the clinical findings, knee scores, KT-1000 or isokinetic muscle strength. Tunnel widening is marked in the hamstring group. Tunnel widening does not correlate with instability or a poor clinical outcome in the short term. The long-term implications of this finding are still to be determined. Received: 11 March 1998 Accepted: 14 September 1998     

Behavior of the graft within the bone tunnels following anterior cruciate ligament reconstruction, studied by cinematic magnetic resonance imaging

The behavior of a ligament graft following cruciate ligament reconstruction is still an area of limited knowledge. Cinematic magnetic resonance imaging (MRI) offers the possibility of visualizing the graft, including the graft tunnels and fixation during knee motion. Twenty-three patients underwent cinematic MRI (0.2 T; Artoscan) mean ¶23.4 months (range 14–39 months) after autologous anterior cruciate ligament reconstruction (eight bone-tendon-bone, seven semitendinosus-gracilis, and eight iliotibial band). The images were read without knowledge of the clinical condition or the type of surgery performed. Signal intensity and continuity of the anterior cruciate ligament reconstruction and movement of the graft in the tibial or femoral tunnel anteriorly and posteriorly were noted. In two of the 23 patients the graft (semitendinosus-gracilis) moved in the tibial canal. The initial 9-mm tunnel had expanded by 2 mm in the anteroposterior direction at the entrance to the joint space. Only these two had a slight knee laxity, with a side-to-side difference in anterior translation measured by the KT-2000 of 4 and ¶5 mm. No movement was observed in any of the femoral tunnels. Cinematic MRI thus makes it possible to study graft behavior within the bone tunnels.