A prospective evaluation of tunnel enlargement in anterior cruciate ligament reconstruction with hamstrings: extracortical versus anatomical fixation

Changes in the femoral and tibial bone tunnel were studied prospectively after arthroscopic ACL reconstruction with quadruple hamstring autograft. To determine whether tunnel enlargement can be decreased by fixing the graft close to the joint line having a stiffer fixation construct we compared "anatomical" (one absorbable interference screw femorally, and bicortical fixation with two absorbable interference screws tibially) and extracortical fixation techniques (Endobutton femorally, and two no. 6 Ethibond sutures over a suture washer tibially). Over a 2-year period we evaluated 60 patients clinically (IKDC scale, Cincinnati Knee Score, KT-1000) and radiographically (confirmed by MRI). The operated knee was radiographed immediately postoperatively and 6 and 24 months postoperatively. The femoral and tibial bone tunnel diameter was measured on anteroposterior and lateral images, and the tunnel area was calculated and compared to the initial area calculated from the perioperative drill size. In the "anatomical" group the immediately postoperative bone tunnel area was 75% larger than the initial tunnel area, after 6 months it was increased another 31%, and between 6 and 24 months it remained basically unchanged. In the "extracortical" group there was no significant enlargement immediately postoperatively, but after 6 months it was 65% larger than the initial area of drill and graft size, and between 6 and 24 months it decreased to 47%. There was no correlation between the amount of tunnel enlargement and clinical scores or KT-1000 measurement. Arthroscopic ACL reconstruction with quadruple hamstring autograft is associated with bone tunnel enlargement. Using a purely extracortical fixation technique thus significantly increased the tibial and femoral tunnel area during the first 6 postoperative months, while it decreased slightly thereafter. The insertion of large interference screws apparently not only compresses the graft in the bone tunnel but also significantly enlarges the bone tunnel itself. The immediate enlargement at the time of the operation is followed by a reduced further enlargement at 6 months and then stabilization. Tunnel widening did not influence clinical outcome over a 2-year period.     

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.     

Femoral tunnel enlargement after anatomic ACL reconstruction: a biological problem?

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.     

The mid- to long-term results of the anterior cruciate ligament reconstruction with hamstring tendons using Transfix technique

In this study, mid to long-term results of anterior cruciate ligament reconstruction with hamstring tendons and Transfix technique were evaluated. Anterior cruciate ligament (ACL) reconstruction with four-strand hamstring tendon was performed with Transfix technique on 271 (198 males, 73 females; mean age 25.7; 17–52) patients with anterior cruciate ligament ruptures. The patients were followed up with clinical examination, Lysholm and Tegner activity scales, IKDC scoring system, KT-1000 test and radiological examination. The mean follow-up period was 82 (48–100) months; 204 (75%) patients had no subjective complaints. According to the KT-1000 test, only 14 (5%) patients had more than 5 mm laxity postoperatively, whereas, 161 (59%) patients had more than 5 mm laxity preoperatively. In addition to this, only 19 (7%) patients had Lysholm scores less than 80 postoperatively, whereas 154 (57%) patients scored less than 80 preoperatively. When compared with Tegner activity scale, 189 (70%) patients scored <6 preoperatively and only 24 (8%) postoperatively; 78 (29%) patients scored D preoperatively and only 5 (2%) patients scored D postoperatively on the basis of the IKDC scoring system. Our functional results were found to be satisfactory in more than 90% of patients. Commonly seen problems in ACL reconstruction such as inaccurate graft placement and tunnel widening were found to be consistent with the values in relevant literature. However, we demonstrated that the functional results and the stability of the knee were not related with tunnel widening. This study concludes that the reconstruction of ACL with hamstring tendons and the Transfix technique is reasonably successful, safe and causes low morbidity. Furthermore, we believe that proper graft preparation, accurate tunnel placement, notch-plasty, fixation and rehabilitation program are all as important as the choice of graft and fixation material.     

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.     

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.     

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).     

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     

The attic of the femoral tunnel in anterior cruciate ligament reconstruction: a comparison of outcomes of two suspensory femoral fixation systems

Purpose

This study aimed to find answers to the following questions: (1) Is it possible to determine and measure the space between the top of the graft and entrance of implant tunnel by magnetic resonance imaging (MRI)? (2) Is there any correlation between the hole above the graft in femoral tunnel and the femoral tunnel widening? (3) Does the tunnel widening affect clinical outcomes? (4) Are clinical and radiological outcomes of Toggle Loc with Zip Loop implant-loop design better than Endobutton CL?

Methods

The operative data of two surgeons were analysed. One surgeon used Endobutton CL femoral fixation (E-CL group, n = 46); the other used Toggle Loc with Zip Loop femoral fixation (TL-ZL group, n = 32). At the last follow-up, clinical evaluation was performed with International Knee Documentation Committee Subjective Knee Form (IKDC), Tegner activity scale, Lysholm score, active and passive ROM, Lachman and pivot shift tests, and KT-1000 arthrometer. Radiological evaluation including measurement of tunnel widening on X-ray and MRI and the height of attic of femoral tunnel (space above the graft in femoral tunnel) on MRI was performed.

Results

No difference was found in patient demographics, concomitant meniscal surgery and clinical outcomes. The femoral tunnel widening was evaluated significantly low in TL-ZL group on the PA X-ray and MRI. No difference was observed in the tibial tunnel widening on X-ray and MRI. A correlation between the height of attic of femoral tunnel and the femoral tunnel widening was determined. Thus, the greater the height of attic of femoral tunnel, the greater the femoral tunnel widening. No correlation was established between the tunnel widening and IKDC and Lysholm scores.

Conclusions

The results of this study demonstrate that a positive correlation exists between the height of the attic of the femoral tunnel and femoral tunnel widening. Therefore, increasing the height of the attic of the femoral tunnel may contribute to graft motion, which would then enhance femoral tunnel widening.

Level of evidence

III.     

Graft choice and graft fixation in PCL reconstruction

Several grafts and several fixation techniques have been introduced for PCL reconstruction over the past years. To date, autograft and allograft tissues are recommended for PCL reconstruction, whilst synthetic grafts should be avoided. Autograft tissues include the bone-patellar tendon-bone graft, the hamstrings and the quadriceps tendon. Allograft tissues are increasingly being used for primary PCL reconstruction. The use of allograft tissues requires a number of formal prerequisites to be fulfilled. Besides the previous mentioned graft types allograft tissues include Achilles and tibialis anterior/posterior tendons. To date no superior graft type has been identified. Several techniques and devices have been used for fixation of a PCL replacement graft. Most of these were originally developed for ACL reconstruction and then adapted to PCL reconstruction. However, biomechanical requirements of the PCL differ substantially from those of the ACL. To date, requirements for PCL graft fixations are not known. From a systematic approach femoral graft fixation can either be achieved within the bone tunnel (nearly anatomic) with an interference screw or outside the bone tunnel on the medial femoral condyle using a staple, an endobutton or a screw. Tibial graft fixation can be achieved either with an interference screw in the bone tunnel or with a staple, screw/washer or sutures tied over a bone bridge outside the bone tunnel (extra-anatomic). An alternative fixation on the tibial side is the inlay technique that reduces the acute angulation of the graft at the posterior aspect of the tibia. Further research is necessary to identify the differences between the various fixation techniques.     

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: fact or fiction?

Radiographic enlargement of bone tunnels following anterior cruciate ligament (ACL) reconstruction has been recently introduced in the literature; however, the etiology and clinical relevance of this phenomenon remain unclear. While early reports suggested that bone tunnel enlargement is mainly the result of an immune response to allograft tissue, more recent studies imply that other biological as well as mechanical factors play a more important role. Biological factors associated with tunnel enlargement include foreign-body immune response (against allografts), non-specific inflammatory response (as in osteolysis around total joint implants), cell necrosis due to toxic products in the tunnel (ethylene oxide, metal), and heat necrosis as a response to drilling (natural course). Mechanical factors contributing to tunnel enlargement include stress deprivation of bone within the tunnel wall, graft-tunnel motion, improper tunnel placement, and aggressive rehabilitation. Graft-tunnel motion refers to longitudinal and transverse motion of the graft within the bone tunnel and can occur with various graft types and fixation techniques. Aggressive rehabilitation programmes may contribute to tunnel enlargement as the graft-bone interface is subjected to early stress before biological incorporation is complete. Further basic research is required to verify the effect of the various proposed factors on the etiology of bone tunnel enlargement. We recommend that routine follow-up examinations after ACL reconstruction should include the measurement of bone tunnel size in order to contribute to a better understanding of the incidence, time course, and clinical relevance of this phenomenon. Improved and more anatomical surgical fixation techniques may be useful for the prevention of bone tunnel enlargement.     

Anterior cruciate ligament reconstruction with double-looped semitendinosus and gracilis tendon graft directly fixed to cortical bone: 5-year results

Forty-three patients who had undergone an anterior cruciate ligament (ACL) reconstruction using a doubled semitendinosus and gracilis graft were prospectively reviewed at 5-year follow-up. All had suffered subacute or chronic tears of the ligament. At surgery, the femoral tunnel was drilled first through the antero-medial portal. The correct position of the femoral and tibial guide wire was checked fluoroscopically. A cortical fixation to the bone was achieved in the femur with a Mitek anchor, directly passing the two tendons in the slot of the anchor, and in the tibia with an RCI screw, supplemented with a spiked washer and bicortical screw. Rehabilitation was aggressive, controlled and without braces. The International Knee Documentation Committee (IKDC) form, KT-1000 arthrometer, and Cybex dynamometer were employed for clinical evaluation. A radiographic study was also performed. At the 5-year follow-up all the patients had recovered full range of motion and 2% of them complained of pain during light sports activities. Four patients (9.5%) reported giving-way symptoms. The KT-1000 side-to-side difference was on average 2.1 mm at 30 lb, and 68% of the knees were within 2 mm. The final IKDC score showed 90% satisfactory results. There was no difference between the 2-year and 5-year evaluations in terms of stability. Extensor and flexor muscle strength recovery was almost complete (maximum deficit 5%). Radiographic study showed a tunnel widening in 32% of the femurs and 40% of the tibias. A correlation was found between the incidence of tibial tunnel widening and the distance of the RCI screw from the joint (the closer the screw to the joint, the lower the incidence of widening). In conclusion, we can state that, using a four-strand hamstring graft and a cortical fixation at both ends, we were able to achieve satisfactory 5-year results in 90% of the patients.     

The effect of accelerated,brace free,rehabilitation on bone tunnel enlargement after ACL reconstruction using hamstring tendons: a CT study

The mechanism of bone tunnel enlargement following anterior cruciate ligament (ACL) reconstruction is not yet clearly understood. Many authors hypothesized that aggressive rehabilitation protocols may be a potential factor for bone tunnel enlargement, especially in reconstructions performed with hamstrings autograft. The purpose of this study was to evaluate the effect of a brace free rehabilitation on the tunnel enlargement after ACL reconstruction using doubled semitendinosus and gracilis tendons (DGST): our hypothesis was that early post-operative knee motion increase the diameters of the tibial and femoral bone tunnels. Forty-five consecutive patients undergoing ACL reconstruction for chronic ACL deficiency were selected. All patients were operated by the same surgeon using autologous DGST and the same fixation devices. Patients with associated ligaments injuries and or severe chondral damage were excluded. The patients were randomly assigned to enter the control group (group A, standard post-operative rehabilitation) and the study group (group B, brace free accelerated rehabilitation). A CT scan was used to exactly determine the diameters of both femoral and tibial tunnels at various levels of lateral femoral condyle and proximal tibia, using a previously described method [17]. Measurements were done by an independent radiologist in a blinded fashion the day after the operation and at a mean follow-up of 10 months (range 9–11). Statistical analysis was performed using paired t-test. The mean femoral tunnel diameter increased significantly from 9.04 ± 0.05 (post-operative) to 9.30 ± 0.8 mm (follow-up) in group A and from 9.04 ± 0.03 to 9.94 ± 1.12 mm in group B. The mean tibial tunnel diameter increased significantly from 9.03 ± 0.04 to 10.01 ± 0.80 mm in group A and from 9.04 ± 0.03 to 10.60 ± 0.78 mm in group B. The increase in femoral and tunnel diameters observed in the study group was significantly higher than that observed in the control group. Our results suggest that bone tunnel enlargement after ACL reconstruction using hamstrings autograft can be increased by an accelerated, brace free, rehabilitation protocol.     

Tunnel enlargement after anterior cruciate ligament reconstruction in patients with post-operative septic arthritis

Tunnel enlargement is a frequent issue after ACL reconstruction and the “synovial bathing effect” is thought to be among the biological factors contributing to this phenomenon. Since the amount and the pressure of the synovial fluid inside the knee joint are higher and the length of its presence is longer in patients with post-operative septic arthritis after ACL reconstruction, we reviewed the tunnel enlargement in these cases in order to better evaluate this phenomenon in such a hostile environment. The null hypothesis of this study was that the highly represented phenomenon of the “synovial bathing effect” that occurs in an infected ACL reconstruction would not affect the amount of post-operative tunnel widening. A case-control study was done. At a mean follow up of 10 months (range 9–11 months) eight patients with septic arthritis following ACL reconstruction (group A) were radiologically reviewed using a CT scan and the diameters of femoral and tibial tunnels were measured. The results were compared with a control group (B) of uncomplicated ACL reconstruction cases operated by the same surgeon using the same technique. Although patients of Group A experienced a bigger amount of tunnel enlargement than patients of group B both on femoral (9.53 ± 1.07 vs. 9.35 ± 1.52 mm) and tibial side (10.07 ± 1.3 vs. 9.92 ± 0.74 mm), no clinical or statistically significant differences were detected between the groups (P > 0.05). No significant tunnel enlargement could be detected in patients of group A when compared with patients of group B. This seems to minimize the role of biological factors contributing to tunnel widening.     

Bone tunnel enlargement after anterior cruciate ligament reconstruction with the hamstring autograft and endobutton fixation technique A clinical, radiographic and magnetic resonance imaging study with 2 years follow-up

The aim of this study was to describe the contrast-enhanced magnetic resonance imaging (MRI) appearance of bone tunnel enlargement detected on radiography after anterior cruciate ligament (ACL) reconstruction with semitendinosus and gracilis tendon endobutton (STG-endobutton) fixation technique. Fourteen patients with a STG-endobutton ACL reconstruction were examined 3 months (n = 1), 1 year (n = 1) and 2 years (n = 12) postoperatively. An age- and sex-matched group with a bone–patellar tendon–bone (BTB) autograft ACL reconstruction with similar follow-up was taken as control. Data on clinical examination, laxity and isokinetic muscle torque measurements, anteroposterior and lateral view radiography were obtained, and knee scores (Lysholm and Tegner) were collected. Contrast-enhanced MRI was performed in the STG-endobutton group with a 1.5-T imager. There were no statistical differences between the groups with respect to clinical findings, stability tests, or knee scores. In the STG-endobutton group the average femoral and tibial bone tunnel diameter detected on anteroposterior view radiography had increased at 2-year follow-up by 33% and 23%, respectively. On MRI the ligamentous graft itself was not enhanced by the contrast medium whereas periligamentous tissue within and around the STG graft bundles showed mild contrast enhancement. In conclusion, the MRI results suggest that enhancing periligamentous tissue accumulated in and around the STG graft associated with the tunnel expansion. In spite of the significant bone tunnel enlargement observed on the follow-up radiography the STG-endobutton knees were stable and the patients satisfied. Received: 26 January 1999 Accepted: 22 May 1999     

Effect of suturing the femoral portion of a four-strand graft during an ACL reconstruction

Purpose

A suture passed along the part of the graft that will be inserted into the femoral tunnel is widely used by surgeons, because it could prevent the graft sliding on the femoral fixation device during pulling from the tibial side. The aim of this study was to evaluate the biomechanical effects of suturing the intratunnel femoral part of the graft during an anterior cruciate ligament (ACL) reconstruction.

Methods

Bovine digital extensor tendons and tibias were harvested from 20 fresh-frozen mature bovine knees ranging in age from 18 to 24 months. Quadruple-strand bovine tendons were passed through the tibial tunnel and secured distally with a bioabsorbable interference screw. In one half of all grafts (N = 10), the looped-over part of the graft was sutured in a whipstitch technique over a distance of 30 mm (Group 1). In one half of all grafts (N = 10), the looped-over part was left free from any suture (Group 2). The grafts were preconditioned at 50 N for 10 min, followed by cyclic loading at 1 Hz between 50 N and 250 N for 1,000 cycles. Load-to-failure test was then carried out at a rate of 1 mm/s.

Results

There was no statistically significant difference between mean stiffness at pullout and yield load between the two groups. In all specimens on Group 1, failure occurred following to partial breaking and then slipping of the tendons between the screw and the tunnel. Concerning Group 2, in six cases failure occurred as described for Group 1 specimens. In the remaining four cases, failure occurred entirely through the ligament mid-substance.

Conclusions

Suturing in a whipstitch fashion the femoral portion of the graft doesn’t affect the mechanical proprieties of the ACL graft. When suspension fixation device is used, suturing the looped-over part of the graft could be helpful in order to provide equal tension in all of the strands of the graft at time of tibial fixation.     

The drill wobble effect: oversizing the femoral tunnel during ACL reconstruction

Objectives: In ACL reconstruction, autologous tendon graft can be attached to the femur, within a boney tunnel, using an Endobutton device. The ultimate aim being to achieve biological fixation and incorporation into the bone. Accurate bone tunnel diameter to match the tendon graft is vital to biologic incorporation and strength. The common technique of in sequence passing a guide wire, a cannulated 4.5 mm Endobutton drill, then a cannulated femoral socket drill causes the guidewire to lose cortical fixation and stability before the femoral socket drill is passed.

The Objective of this study is to analyze this common technique of femoral socket creation and determine if it results in unintentionally oversizing the femoral socket due to femoral socket drill-wobble over a destabilised guide wire.

Methods: 12 cadaveric femoral pairs equally divided between two groups underwent femoral socket creation in one of the two following sequences.

Group 1: Guidewire, 4.5 mm endobutton drill, 8 mm femoral socket drill. Group 2: Guidewire, 8 mm femoral socket drill, 4.5 mm endobutton drill. The created femoral tunnels apertures and calibres were measured and then compared for accuracy between the two groups.

Results: Passing the 4.5 mm drill before the 8 mm socket drill results in oversized tunnel apertures and calibres when compared to passing an 8 mm socket drill after the 4.5 mm drill has been passed (p<0.0001).

Conclusion: To most precisely create an 8 mm femoral socket in ACL reconstruction, the 8 mm femoral socket reamer followed by the 4.5 mm should be passed over the guide wire to prevent guide wire destabilization and drill-wobble.     

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.     

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.