The effect of early motion on tibial tunnel widening after anterior cruciate ligament replacement using hamstring tendon grafts

Long-term effects of non-weight bearing and immobilization after anterior cruciate ligament reconstruction on joint contracture formation in rats

PURPOSE

Non-weight bearing improves and immobilization worsens contracture induced by anterior cruciate ligament reconstruction (ACLR), but effect persistence after reloading and remobilization remains unclear, and the combined effects of these factors on ACLR-induced contracture are unknown. We aimed to determine 1) whether the effects of short-term (2-week) non-weight bearing or immobilization after ACLR on contracture would be sustained by reloading or remobilization during a 10-week observation period, and 2) how the combination of both interventions compared to the outcome of either alone.

METHODS

We divided 88 ACL-reconstructed male rats into four groups: non-intervention, non-weight bearing, joint immobilization, and both interventions. Interventions were performed for 2 weeks, followed by rearing without intervention. Twelve untreated rats were used as controls. At 2, 4, and 12 weeks post-surgery, we assessed range of motion (ROM) and histological changes.

RESULTS

ACLR resulted in persistent loss of ROM, accompanied by synovial shortening, capsule thickening, and osteophyte formation. Two weeks of non-weight bearing increased ROM and reduced osteophyte size, but the beneficial effects disappeared within 10 weeks after reloading. Two-week immobilization decreased ROM and facilitated synovial shortening. After remobilization, ROM partially recovered but remained below non-intervention levels at 12 weeks. When both interventions were combined, ROM was similar to immobilization alone.

CONCLUSIONS

The beneficial effects of 2-week non-weight bearing on contracture diminished within 10 weeks after reloading. The adverse effects of 2-week immobilization on contracture persisted after 10 weeks of remobilization. The effects of the combined use of both interventions on contracture were primarily determined by immobilization.

No Difference in Bone Tunnel Enlargement and Clinical Outcome between Cortical Suspension and Hybrid Femoral Fixation in Hamstring Anterior Cruciate Ligament Reconstruction

OBJECTIVE

The best method for femoral fixation in anterior cruciate ligament reconstruction (ACLR) remains controversial. The study assesses the bone tunnel enlargement and clinical outcome in hamstring ACLR using cortical suspension or hybrid (cortical suspension and compression) femoral fixation.

METHODS

From January 2010 to December 2021, 102 patients who underwent quadruple hamstring ACLR using cortical suspension (39 patients) or hybrid (63 patients) fixation on the femoral side were retrospectively analyzed. Clinical evaluation was conducted using the international knee documentation committee score, the Lysholm score, the Tegner activity level scale, the knee injury and osteoarthritis outcome score (quality of life score), the Lachman test, and the side-to-side difference by the KT-1000 arthrometer. The complications after the surgery were also evaluated. These data were compared at baseline and last follow-up. The diameters of the femoral tunnel were calculated at three sites: the width of the entrance of the femoral tunnel, 1 cm proximal to the entrance of the femoral tunnel and the largest diameter of the femoral tunnel on magnetic resonance imaging (MRI) coronal images. Bone tunnel widening data were contrasted between MRI images conducted at least 2 years and within 2 weeks after surgery. The morphology of bone tunnel enlargement was also observed and recorded. The categorical parameters were analyzed using the χ2-test and Fisher's exact test. The continuous variables conforming to a normal distribution were analyzed using Student's t-test, and the Mann-Whitney U-test was undertaken between the two groups without normal distribution.

RESULTS

Both cortical suspension and hybrid femoral fixation in quadruple hamstring ACLR achieved significantly improved patient-reported outcome scores and knee stability compared to preoperative data. However, no significant differences were found between these two methods in clinical evaluations, postoperative complications, and patient-reported outcome scores. Although the mean diameter of the enlarged bone tunnel was lowered by an additional bioabsorbable interference screw fixation near the joint line, a statistically insignificant difference was found between the hybrid and cortical suspension fixation on the femoral side. There was no statistical difference in the distribution of enlarged bone tunnel morphology between groups.

CONCLUSIONS

No significant difference was found in the bone tunnel enlargement and clinical outcome between cortical suspension and hybrid femoral fixation in ACLR using hamstring autograft.

Less tunnel enlargement in triple-bundle versus double-bundle anterior cruciate ligament reconstruction: A randomized clinical trial

BACKGROUND

No study thus far has compared tunnel enlargement between double-bundle and triple-bundle anterior cruciate ligament reconstruction. We compared tibial tunnel enlargement and rate of tibial tunnel coalition between these two reconstructions, hypothesizing that tibial tunnel enlargement in triple-bundle reconstruction is less than that in double-bundle reconstruction, and that the tunnel coalition rate is equal between the two procedures.

METHODS

This prospective randomized clinical trial included 25 patients who underwent computed tomography 2 weeks and 1 year postoperatively. Eleven patients underwent double-bundle anterior cruciate ligament reconstruction and 14 underwent triple-bundle anterior cruciate ligament reconstruction. Tunnel positions and tunnel coalition at the tibial tunnel aperture were assessed using three-dimensional computed tomography. Tunnel enlargement rate was calculated by measuring the sagittal and axial widths of the tibial bone tunnel 10 mm from the tibial tunnel aperture. These parameters were then compared between the groups.

RESULTS

The changes in tunnel positions and tunnel coalitions between groups were not significantly different. On both sagittal and axial views, the tunnel enlargement rates of the medial and lateral sections of the anteromedial bundle in the triple-bundle group were significantly smaller than those in the double-bundle group (sagittal view, p = 0.02 and < 0.01, respectively; axial view, p = 0.02 and ≤ 0.05, respectively). The groups did not differ significantly in terms of posterolateral tunnel enlargement.

CONCLUSION

Tunnel widening in the medial and lateral sections of the anteromedial bundle-associated tibial tunnel in triple-bundle anterior cruciate ligament reconstruction was smaller than that of double-bundle reconstruction. The tunnel coalition rates between the two reconstructions were not significantly different.

Low Femoral Tunnel Widening Incidence Rate After ACL Reconstruction Using Patellar Tendon Graft with Press-Fit Fixation

Background

Femoral tunnel widening after ACL reconstruction is a common phenomenon. We hypothesized that using a patellar tendon graft with a press-fit fixation technique without any fixation device reduces the incidence of femoral tunnel widening.

Methods

This study was conducted on 467 patients with ACL surgery between 2003 and 2015. Two hundred and nineteen of them had an ACL surgery with patellar tendon (PT) graft, and two hundred and forty-eight of them with hamstring tendon (HS). Exclusion criteria were history of previous ACL reconstruction of either knee, multiple ligament injury, or evidence of osteoarthritis on radiographs. The femoral tunnels were measured on the anteroposterior (ap) and lateral radiographs 6 months after the operation. Two independent orthopedic surgeons measured all radiographs twice and recorded the tunnel widenings. We hypothesized that using an implant-free press-fit technique with PT graft can reduce the femoral tunnel widening incidence rate.

Results

The mean incidence rate of the tunnel widening in the HS group was, on the AP and the lateral femoral views, 88% (n = 217) and 83% (n = 205), while in the PT group, 17% (n = 37) and 2% (n = 4), respectively. There was a significant difference both on AP and lateral radiographs (HS vs. PT: fem. AP: 89% vs. 17% p < 0.001; HS vs. PT: fem. lat: 84% vs. 2% p < 0.001).

Conclusion

The femoral tunnel widening incidence rate during an ACL reconstruction is significantly less when using PT tendon with femoral press-fit fixation than when using HT tendon with suspensory fixation method.

Does Accelerated Rehabilitation Provide Better Outcomes Than Restricted Rehabilitation in Postarthroscopic Repair of Meniscal Injury?

CONTEXT

Meniscal injury is a common pathology, and the postoperative rehabilitation program is essential to patients after surgery. However, the optimal rehabilitation plan after meniscus suture is still controversial.

OBJECTIVE

To compare the clinical outcomes between accelerated rehabilitation and restricted programs in patients with meniscus suture (with or without anterior cruciate ligament reconstruction, ACLR).

EVIDENCE ACQUISITION

Four databases, including PubMed, Ovid, Embase, and the Cochrane Library, were searched up to November 2021. This study only included studies comparing the clinical outcomes between accelerated (immediate range of motion and weight-bearing) and restricted rehabilitation (immobilization and progressive weight-bearing) for meniscus suture. All selected studies were divided into 2 subgroups: isolated meniscus suture or combined with ACLR. The Lysholm score, Tegner score, and Knee Injury and Osteoarthritis Outcome Score were evaluated in simple meniscus sutures no less than 1 year. Failure rate was evaluated in both groups, and the tunnel enlargement was additionally evaluated in patients who underwent ACLR.

EVIDENCE SYNTHESIS

Eleven studies with 612 patients were eligible for analysis. The accelerated group included 4 studies with 330 participants, while the restricted group included 7 studies with 282 participants. For the patients after isolated meniscus suture, the accelerated group achieved higher Lysholm scores (mean difference = -4.66; 95% confidence interval, -8.6 to -0.73; P = .02; I2 = 88%) than the restricted group. For the patients after meniscus suture with ACLR, patients undergoing accelerated rehabilitation were associated with a significantly larger tibial tunnel enlargement in the anterior-posterior view (mean difference = -7.08; 95% confidence interval, -10.92 to -3.24; P = .0003; I2 = 0%) and lateral view (mean difference = -10.33; 95% confidence interval, -16.9 to -3.75; P = .002; I2 = 17%).

CONCLUSION

This meta-analysis evaluated the effects of postoperative rehabilitation in either accelerated or restricted programs in patients with meniscus lesions after repair. A significant higher mean self-reported function was discovered at final follow-ups in the accelerated group. However, a significant increase in tibial tunnel enlargement was also found in accelerated group.

The effects of immobilization duration on joint contracture formation after anterior cruciate ligament reconstruction in rats

BACKGROUND

Both myogenic and arthrogenic factors contribute to contracture formation after anterior cruciate ligament reconstruction surgery. However, effects of immobilization duration on myogenic and arthrogenic contractures after surgery are unknown. We examined the effects of immobilization duration on contracture formation.

METHODS

Rats were divided into groups according to treatment received: untreated control, knee immobilization, anterior cruciate ligament reconstruction, and anterior cruciate ligament reconstruction plus immobilization. Extension range of motion before and after myotomy as well as histomorphological knee changes were assessed two or four weeks after experiment commencement. Range of motion before myotomy mainly represents contractures due to myogenic factors. Range of motion after myotomy represents arthrogenic factors.

FINDINGS

Range of motion before and after myotomy was decreased in the immobilization, reconstruction, and reconstruction plus immobilization groups at both timepoints. In the reconstruction plus immobilization group, range of motion before and after myotomy was significantly smaller than in the immobilization and reconstruction groups. Shortening and thickening of the posterior joint capsule was induced in the immobilization and reconstruction groups. In the reconstruction plus immobilization group, capsule shortening was facilitated via adhesion formation, as compared to the immobilization and reconstruction groups.

INTERPRETATION

Our results indicate that immobilization after anterior cruciate ligament reconstruction surgery facilitates contracture formation via exacerbation of both myogenic and arthrogenic contractures within two weeks. Capsule shortening would be one of the main mechanisms for severe arthrogenic contracture observed in the reconstruction plus immobilization group. Periods of joint immobilization after surgery should be minimized to reduce contracture.

Synergistic Effect of Reverse Drilling and Bone Dust on Femoral Tendon-Bone Healing After Anterior Cruciate Ligament Reconstruction in a Rabbit Model

BACKGROUND

Anterior cruciate ligament (ACL) injuries and bone tunnel enlargement (BTE) after ACL reconstruction (ACLR) remain frequent issues. Bone dust (BD) produced by tunnel preparation with osteogenic ability and reverse drilling (RD), an easy compaction technique, make it accessible to enhance tendon-bone healing in the clinic.

HYPOTHESIS

RD and BD synergistically promote tendon-bone healing by improving peritunnel bone and preventing BTE in femurs.

STUDY DESIGN

Controlled laboratory study.

METHODS

In total, 96 New Zealand White rabbits underwent ACLR. The semitendinosus tendon was freed before medial parapatellar arthrotomy. After the native ACL was transected, bone tunnels were prepared through the footprint of the native ACL. All animals were randomly assigned to 1 of 4 groups according to different tunnel preparation methods: group 1 (irrigation after extraction drilling [ED]; control group), group 2 (irrigation after RD), group 3 (no irrigation after ED), and group 4 (no irrigation after RD). BD was harvested by irrigating tunnels and was characterized by morphology and size. The specimens underwent microarchitectural, histological, and biomechanical evaluations at 4, 8, and 12 weeks postoperatively.

RESULTS

Micro-computed tomography demonstrated more peritunnel bone and less BTE in the femurs of group 4 compared with the other groups. Histologically, BD possessed osteogenic activity in bone tunnels postoperatively. Meanwhile, group 4 regenerated a higher amount of the tendon-bone interface and more peritunnel bone than group 1. Biomechanically, group 4 showed higher failure loads and stiffness than group 1. However, peritunnel bone loss, active osteoclasts, and significant BTE were found in the femurs of group 1 and group 3 at 12 weeks postoperatively, while no strong correlation was found between BTE and inflammatory cytokines. Scanning electron microscopy and particle size analysis suggested that BD produced by ED and RD had no difference in size.

CONCLUSION

Tendon-bone healing was facilitated by the synergistic effect of RD and BD in femurs.

CLINICAL RELEVANCE

This study provides a more accessible and effective surgical strategy to promote tendon-bone healing after ACLR by increasing peritunnel bone and preventing BTE in femurs.

Comparison of Rapid Rehabilitation after Anterior Cruciate Ligament Reconstruction with Tensioning Technique and Traditional Rehabilitation

To investigate the efficacy of a fast rehabilitation program for the recovery of knee joint function after arthroscopic autologous hamstring tendon transplantation for reconstruction of the anterior cruciate ligament (ACL), from January 1, 2017, to March 31, 2019, a total of 65 patients with ACL injury were randomly divided into a study group and a control group. Both groups were treated with autologous hamstring tendon to reconstruct the anterior cruciate ligament, arthroscopic transplantation, and decompression techniques. The research group was treated with a fast rehabilitation program. The control group was treated with traditional rehabilitation program. Knee flexion angles were measured at 2, 4, and 8 weeks postoperatively. KT-1000 knee anterior stability was measured at 3, 6, and 12 months after operation. Knee function was assessed by subjective knee function assessment scale (IKDC) and Lysholm knee score. The knee curvature, KT-1000 measurement, IKDC score, and Lysholm score were compared between the two groups before and after treatment. KT-1000 measured value, IKDC score, and Lysholm score in 2 groups were significantly improved 3, 6, and 12 months compared with those before treatment, and the difference was statistically significant (P < 0.001). Comparison between the two groups: 2 weeks, 4 weeks, and 8 weeks after treatment, the knee curvature in the study group was better than that in the control group, and the difference was statistically significant (P < 0.001); there was no significant difference in the measured values of KT-1000 between the two groups 3, 6, and 12 months after treatment (P > 0.05); IKDC score and Lysholm score in the study group 3 and 6 months after treatment were significantly better than those in the control group, with statistical significance (P < 0.001); there was no significant difference in IKDC score and Lysholm score between the two groups 12 months after treatment (P >0.05). Autograft hamstring tendon transplantation and tense-reducing technique for anatomical reconstruction of anterior cruciate ligament under arthroscopy combined with rapid rehabilitation program can quickly, safely, and effectively restore the knee function of patients, greatly shortening the rehabilitation period of patients.

Tibial graft fixation methods and bone tunnel enlargement: A comparison between the TensionLoc implant system and the double-spike plate

Background/objective

TensionLoc (Arthrex, Naples, Florida, USA), a tibial graft fixation system for anterior cruciate ligament (ACL) reconstruction, is expected to apply the preoperatively determined level of graft tension and allow setting of lower initial tension. Considering its mechanism, we hypothesised that TensionLoc would prevent postoperative bone tunnel enlargement (TE) through fixation with lower initial tension. Therefore, the present study aimed to compare TE between ACL reconstructions using the double-spike plate (DSP; Smith and Nephew, Andover, Massachusetts) and TensionLoc implant system.

Methods

A total of 40 patients who underwent anatomical single-bundle ACL reconstruction with a hamstring tendon graft were retrospectively analysed. In the group in which DSP and screw were used, the initial graft tension was set to 40 N at 20° of knee flexion (group D). In the other group in which TensionLoc was used, the initial graft tension was set to 30 N at 20° of knee flexion (group T). Both groups included 20 patients each. Tunnel areas were measured using computed tomography images at one week and three months after surgery, and the TE ratio was calculated according to the following equation: TE ratio (%) = (tunnel area at three months after surgery - tunnel area at one week after surgery)/tunnel area at one week after surgery × 100.

Results

The femoral TE ratios were significantly higher in group T (80.5% ± 28.8%) than in group D (45.5% ± 34.6%) (p = 0.001). However, the tibial TE ratios did not significantly differ between the two groups.

Conclusion

Compared with ACL reconstruction using DSP and screw, ACL reconstruction using TensionLoc fixed the graft with lower initial tension but showed greater femoral TE and restricted knee extension in the early postoperative period.

Differences in artificial ligament graft osseointegration of the anterior cruciate ligament in a sheep model: a comparison between interference screw and cortical suspensory fixation

Background

Interference screws are the most common femoral fixation for anterior cruciate ligament (ACL) reconstruction with polyethylene terephthalate (PET) artificial ligaments. However, interference screws have several disadvantages, such as the risk of one tunnel blowout and damage to the graft. Suspensory fixations have the advantages of high tensile strength and promotion of graft bone contact. The purpose of this study was to compare PET artificial ligament graft osseointegration between interference screw fixation (ISF) and cortical suspensory fixation (CSF) for ACL reconstruction.

Methods

Forty sheep underwent ACL reconstruction of the right knee with PET artificial ligament. The graft was fixed with ISF or CSF for femoral fixation. Animals were randomly assigned to the ISF (n=20) or the CSF (n=20) groups. The sheep were sacrificed at 3 or 12 months postoperatively for biomechanical tests, micro computed tomography (micro-CT) scans, and histological assessments.

Results

The mean load-to-failure between the CSF group (836±355 N) appeared higher than that of the ISF group (604±277 N) at 3 months, but no significant difference was detected between the groups (P=0.24). At 12 months, there was also no significant difference in load-to-failure between the CSF and ISF groups (1,194±350 vs. 1,097±764 N; P=0.78). According to the micro-CT scan results, the femoral bone tunnel diameter of the ISF group appeared larger than that of the CSF group at 3 months (12±1 vs. 10±1 mm; P=0.02) and similar to that of the CSF group at 12 months (12±1 vs. 11±2 mm; P=0.38). Furthermore, histological results showed that at the graft-tunnel interface of the femoral tunnel aperture, disoriented fibers formed in the ISF group while oriented and dense fibers formed in the CSF group.

Conclusions

ACLR with synthetic ligament by cortical suspension devices with adjustable loops demonstrated a better graft-bone healing capacity at the femoral tunnel aperture compared with that from titanium interference screws over 12 months postoperatively. No significant difference was found in biomechanical strength between the two fixation methods during the early healing stage.

Influence of Graft Bending Angle on Femoral Tunnel Widening After Double-Bundle ACL Reconstruction: Comparison of Transportal and Outside-In Techniques

Background:

Previous studies have suggested that increased mechanical stress due to acute graft bending angle (GBA) is associated with tunnel widening and graft failure after anterior cruciate ligament (ACL) reconstruction. Few studies have compared the GBA between the outside-in (OI) and the transportal (TP) techniques.

Purpose:

To evaluate the influence of GBA on clinical outcomes and tunnel widening after ACL reconstruction with OI versus TP technique.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included in the study were 56 patients who underwent double-bundle ACL reconstruction (n = 28 in the OI group and n = 28 in the TP group). Clinical outcomes (Lysholm, International Knee Documentation Committee, Tegner score, and knee laxity) 1 year postoperatively were evaluated. Computed tomography scans at 5 days and 1 year postoperatively were used for imaging measurements, and the femoral tunnel was divided into the proximal third, middle, and aperture sections. The GBA and cross-sectional area (CSA) were measured using image analysis software and were compared between groups. A correlation analysis was performed to determine if the GBA affected clinical outcomes or tunnel widening.

Results:

No significant difference was observed in clinical outcomes between the groups. The GBA of both the anteromedial (AM) and posterolateral bundles were more acute in the OI group compared with the TP group (P < .05). The CSA at the AM tunnel aperture increased significantly in the OI group (84.2% ± 64.3%) compared with the TP group (51.4% ± 36.7%) (P = .04). However, there were no differences in the other sections. In the Pearson correlation test, GBA was not correlated with tunnel widening or clinical outcomes.

Conclusion:

Regardless of technique, the GBA did not have a significant influence on tunnel widening or clinical outcomes. Considering a wider AM tunnel aperture, a more proximal and posterior AM tunnel position might be appropriate with the OI technique.

[Influence of lateral posterior tibial slope on tibial tunnel expansion after anatomical single-bundle anterior cruciate ligament reconstruction]

Objective

To investigate the influence of lateral posterior tibial slope (LPTS) on tibial tunnel expansion after anatomical single-bundle anterior cruciate ligament (ACL) reconstruction and the effect of tibial tunnel expansion on knee joint function.

Methods

A clinical data of 52 patients with ACL rupture, who underwent arthroscopic anatomical single-bundle reconstruction between November 2018 and December 2019, was retrospectively analyzed. There were 32 males and 20 females with an average age of 34.3 years (range, 14-64 years). There were 22 cases of left knee and 30 cases of right knee. The time from injury to operation ranged from 7 to 30 days, with an average of 15.9 days. The knee function was evaluated by International Knee Documentation Committee (IKDC) score and Lysholm score before operation and at 3 and 6 months after operation. At 3 and 6 months after operation, the LPTS and the width of exit, middle segment, entrance, and 2 cm from the exit of the articular surface of the tibial tunnel were measured based on MRI. The expansion of tibial tunnel was calculated and graded (degrees 0-3). According to LPTS, the patients were divided into group A (<6.0°), group B (6°-12°), and group C (>12°), and the difference in the expansion of tibial tunnel between groups was compared.

Results

All the 52 patients were followed up 6-12 months (mean, 7.1 months). The IKDC and Lysholm scores at 3 and 6 months after operation were significantly different from those before operation ( P<0.05); and the difference of knee scores between 3 and 6 months after operation was significant ( P<0.05). The tibial tunnel expanded after operation, and the relative expansion at the exit and the middle segment showed significant difference between 3 months and 6 months after operation ( P<0.05). The expansion degree of tibial tunnel was rated as degree 0 in 5 cases, degree 1 in 28 cases, degree 2 in 16 cases, and degree 3 in 3 cases at 3 months after operation, and degree 0 in 5 cases, degree 1 in 20 cases, degree 2 in 25 cases, and degree 3 in 2 cases at 6 months after operation. There was no significant difference in IKDC and Lysholm scores between patients with different expansion degrees of tibial tunnels ( P>0.05). The LPTS of 52 patients ranged from -0.8° to 18.7° (mean, 10.6°); there were 7 cases in group A, 24 cases in group B, and 21 cases in group C. There was no significant difference in age, gender, preoperative IKDC and Lysholm scores, and initial width of tibial tunnel between groups ( P>0.05). There was no significant difference in the relative expansion of tibial tunnel at exit and middle segment between groups at 3 months after operation ( P>0.05), and there was significant difference at 6 months after operation ( P<0.05).

Conclusion

After anatomical single-bundle reconstruction of ACL, the tibial tunnel would expand to some extent in a short time. LPTS had a significant effect on tibial tunnel expansion, and the larger the angle was, the more obvious the expansion of the proximal tibial tunnel was. However, early knee function is not affected by tibial tunnel expansion.

Bioabsorbable interference screws can be used with less tunnel widening in anatomic rectangular tunnel anterior cruciate ligament reconstruction with a bone-patellar-tendon-bone graft

BACKGROUND

The purpose of this study was to investigate postoperative tunnel widening after rectangular tunnel bone-patellar-tendon-bone graft anterior cruciate ligament reconstruction using newer-generation bioabsorbable interference screws.

METHODS

Forty-six patients who had undergone primary rectangular tunnel bone-patellar-tendon-bone graft anterior cruciate ligament reconstruction using MILAGRO bioabsorbable interference screws (DePuy Synthes, Warsaw, IN, USA) for femoral fixation and for whom computed tomography was performed at two weeks and one year postoperatively were included in this prospective study. To assess the tunnel widening, the cross-sectional area of the femoral tunnel aperture (compared between two weeks and one year postoperatively) was assessed using computed tomography. Cyst formation, postoperative screw breakage, screw migration, and graft migration were also evaluated using computed tomography one year postoperatively.

RESULTS

Mean tunnel widening was 1.9%, and the cross-sectional area of the femoral tunnel aperture was not significantly different between two weeks and one year postoperatively. Postoperative cyst formation, screw breakage, screw migration, and graft migration were not observed in any patient.

CONCLUSIONS

After rectangular tunnel bone-patellar-tendon-bone graft anterior cruciate ligament reconstruction using bioabsorbable interference screws for femoral fixation, tunnel widening was not observed via computed tomography analysis at two weeks and one year postoperatively.

Tunnel osteolysis post-ACL reconstruction: a systematic review examining select diagnostic modalities, treatment options and rehabilitation protocols

PURPOSE

The purpose of this systematic review was to (1) identify the optimal diagnostic modality for tunnel widening in skeletally mature patients; (2) identify potentially modifiable risk factors for tunnel widening, such as graft type, and (3) determine what elements of a post-operative rehabilitation program exert the most influence on TW.

METHODS

The electronic databases MEDLINE, EMBASE, PubMed, and Cochrane Library were searched from database inception to January 2018. Studies that discussed tunnel widening following anterior cruciate ligament reconstruction (ACLR) of skeletally mature patients and written in English were included. Descriptive statistics, such as means, ranges, and measures of variance (e.g. standard deviations, 95% confidence intervals (CI)) are presented where applicable.

RESULTS

103 studies (6,383 patients) were included. Plain radiographs were the most commonly used diagnostic modality, but radiographs on average required 10 months longer than CT and 2 months longer on average than MRI to diagnose tunnel widening after ACLR. Although CT was the least commonly used modality, it was the shortest time to diagnose tunnel widening at 9.5 months after ACLR. Bone-patellar tendon-bone (BPTB) allograft had the largest average tunnel widening overall. BPTB autograft had the lowest average tunnel widening overall. Double-bundle hamstring graft configuration had a lower average tunnel widening than single-bundle configuration. Rehabilitation protocols after ACLR that used a full weight-bearing prescription in rehabilitation showed a greater average femoral tunnel widening than partial weight-bearing, and partial weight-bearing showed a greater average tibial tunnel widening than full weight-bearing.

CONCLUSIONS

Based on this systematic review and the descriptive data evaluated, CT demonstrated a time of 9.5 months on average from ACLR to diagnosing tunnel osteolysis post-ACLR. With respect to graft types, double-bundle hamstring autografts reported lower average femoral and tibial TW than single-bundle hamstring autografts. BPTB autografts reported the lowest average TW and BPTB allograft the largest average TW of all the grafts. Furthermore, extension-locked bracing had the lowest TW of all the brace protocols. Lastly, several other surgical technical parameters influencing tunnel osteolysis remain to be determined. No definitive recommendations can be made at this time due to the high heterogeneity of data and the lack of comparative studies analysed in this systematic review.

LEVEL OF EVIDENCE

IV.

Effects of Remnant Tissue Preservation on Tunnel Enlargement After Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Using the Hamstring Tendon

Background

The effects of remnant tissue preservation on tunnel enlargement after anatomic double-bundle anterior cruciate ligament (ACL) reconstruction have not yet been established.

Hypothesis

The preservation of ACL remnant tissue may significantly reduce the degree and incidence of tunnel enlargement after anatomic double-bundle ACL reconstruction, while the remnant-preserving procedure may not significantly increase the incidence of tunnel coalition after surgery.

Study Design

Cohort study; Level of evidence, 2.

Methods

A total of 79 patients underwent anatomic double-bundle ACL reconstruction. Based on the Crain classification of ACL remnant tissue, 40 patients underwent the remnant-preserving procedure (group P), and the remaining 39 patients underwent the remnant-resecting procedure (group R). There were no differences between the 2 groups concerning all background factors, including preoperative knee instability and intraoperative tunnel positions. All patients were examined using computed tomography and a standard physical examination at 2 weeks and 1 year after surgery.

Results

During surgery, the femoral and tibial anteromedial (AM) tunnel sizes in both groups averaged 6.6 and 6.5 mm, respectively. The femoral and tibial posterolateral (PL) tunnel sizes in both groups averaged 6 and 6 mm, respectively. There were no differences in the intraoperative tunnel positions and tunnel sizes between groups. Concerning the femoral AM tunnel, the degree of tunnel enlargement in the oblique coronal and oblique axial views in group P was significantly less than that in group R (P = .0068 and .0323, respectively). Regarding the femoral AM tunnel cross-sectional area, the degree and incidence of tunnel enlargement in group P were significantly less than those in group R (P = .0086 and .0278, respectively). There were no significant differences in tunnel coalition between groups. In each group, there were no significant relationships between tunnel enlargement and each clinical outcome.

Conclusion

Remnant preservation in anatomic double-bundle ACL reconstruction reduced enlargement of the femoral AM tunnel and did not increase the incidence of tunnel coalition. This is one of the advantages of remnant-preserving ACL reconstruction.

Does Second-Generation Suspensory Implant Negate Tunnel Widening of First-Generation Implant Following Anterior Cruciate Ligament Reconstruction?

Purpose

Tunnel widening following anterior cruciate ligament (ACL) reconstruction is commonly observed. Graft micromotion is an important contributing factor. Unlike fixed-loop devices that require a turning space, adjustable-loop devices fit the graft snugly in the tunnel. The purpose of this study is to compare tunnel widening between these devices. Our hypothesis is that the adjustable-loop device will create lesser tunnel widening.

Materials and Methods

Ninety-eight patients underwent ACL reconstruction from January 2013 to December 2014. An adjustable-loop device was used in 54 patients (group 1) and a fixed-loop device was used in 44 patients (group 2). Maximum tunnel widening at 1 year was measured by the L’Insalata’s method. Functional outcome was measured at 2-year follow-up.

Results

The mean widening was 4.37 mm (standard deviation [SD], 2.01) in group 1 and 4.09 mm (SD, 1.98) in group 2 (p=0.511). The average International Knee Documentation Committee score was 78.40 (SD, 9.99) in group 1 and 77.11 (SD, 12.31) in group 2 (p=0.563). The average Tegner-Lysholm score was 87.25 (SD, 3.97) in group 1 and 87.29 in group 2 (SD, 4.36) (p=0.987). There was no significant difference in tunnel widening and functional outcome between the groups.

Conclusions

The adjustable-loop device did not decrease the amount of tunnel widening when compared to the fixed-loop device. There was no significant difference in outcome between the two fixation devices.

Level of Evidence

Level 3, Retrospective Cohort

Tibial tunnel widening following anterior cruciate ligament reconstruction: A retrospective seven-year study evaluating the effects of initial graft tensioning and graft selection

PURPOSE

To investigate tibial tunnel widening in ACL reconstruction patients over seven years to establish the effects of initial graft tension on tibial widening and clinical outcomes when using both patellar tendon (BTB) and hamstring tendon (HS) grafts.

METHODS

Ninety patients, who were reconstructed with BTB or HS autografts, were randomized using one of two initial graft tension protocols; 1) tensioned to restore normal anteroposterior laxity ("low-tension"; n = 46) and 2) tensioned to over-constrain anteroposterior (AP) laxity by two millimeters ("high-tension"; n = 44). Seventy patients had post-surgical data with 45 available for review at seven years. Tunnel widening was assessed via radiographs at one-, three-, and seven-year follow-up. Patient-reported outcomes were compared.

RESULTS

The mean ± 95% confidence intervals of the initial diameters for the BTB autografts were 10.3 ± 0.5 mm (Low-tension) and 10.2 ± 0.6 mm (High-tension) with final diameters of 10.8 ± 0.6 mm (Low-tension) and 9.9 ± 0.6 mm (High-tension). The initial diameters for HS autografts were 8.1 ± 0.9 mm (Low-tension) and 8.4 ± 0.7 mm (High-tension) with final diameters of 11.5 ± 1.1 mm (Low-tension) and 11.1 ± 0.9 mm (High-tension). For subjects with HS autografts, mean tunnel diameters significantly changed over time (p < .001); no significant changes were observed in BTB autografts (p = .29). Change in diameter of the HS autograft group remained significantly greater than the BTB group at all time points for both tension groups (p < .05). No differences in patient-reported outcomes were found between tension groups or graft types.

CONCLUSIONS

Patients who underwent ACL-R with HS autograft exhibited tibial tunnel widening over seven years. Patients with BTB autografts did not experience widening, regardless of initial graft tension. Patient-reported outcomes were equivalent.

Femoral tunnel enlargement after anatomic anterior cruciate ligament reconstruction: Bone-patellar tendon-bone /single rectangular tunnel versus hamstring tendon / double tunnels

PURPOSE

This study aimed to prospectively compare the femoral tunnel enlargement at the aperture as well as inside the tunnel after anatomic anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone (BTB) graft to that with hamstring tendon (HST) graft.

METHODS

This study included 24 patients with unilateral ACL rupture. Twelve patients underwent anatomic rectangular tunnel (ART) ACL reconstruction with BTB graft and the remaining 12 underwent anatomic triple-bundle (ATB) ACL reconstruction with HST graft. Three-dimensional computer models of femur and bone tunnels were reconstructed from computed tomography images obtained at 3 weeks and 1 year postoperatively. The femoral tunnel enlargement from 3 weeks to 1 year was evaluated by comparing the cross-sectional area (CSA), and compared between the two groups.

RESULTS

The CSA in the ART group at 1 year decreased at the aperture as well as inside the tunnel comparing that at 3 weeks. The CSAs of both tunnels in the ATB group at 1 year significantly increased at the aperture in comparison to those at 3 weeks, and gradually decreased toward the inside of the tunnel. The enlargement rate at the aperture in the ART group was -12.9%, which was significantly smaller than that of anteromedial graft (27.9%; P = 0.006) and posterolateral graft (31.3%; P = 0.003) in the ATB group. The tunnel enlargement rate at 5 mm from the aperture in the ART group was also significantly smaller than that in the ATB group. At 10 mm from the aperture, there was no significant difference between the tunnel enlargement rate in the ART group and that of anteromedial tunnel.

CONCLUSIONS

The tunnel enlargement rate around the aperture was significantly smaller after the ART procedure than that after the ATB procedure. Thus, BTB graft might be preferable as a graft material to HST graft in the femoral tunnel enlargement.

The effect of humeral tunnel locations on radiographic tunnel changes in baseball players following medial ulnar collateral ligament reconstruction: comparison of anatomic and nonanatomic locations

BACKGROUND

There has been no study on radiologic changes after medial ulnar collateral ligament (MUCL) reconstruction and related clinical features.

METHODS

Data from 39 baseball players who underwent MUCL reconstruction were collected and analyzed. The baseball players were classified into 2 groups according to the starting point of the humeral tunnel: (1) the lower tip of the medial epicondyle (group NA, n = 21) and (2) the remnant of the MUCL (group A, n = 18). Bone tunnel characteristics and changes were evaluated by computed tomography (CT) at 3 and 9 months postoperatively. Outcome measures consisted of the visual analog scale, range of motion (ROM), the Conway scale, and the presence of ulnar nerve irritation postoperatively.

RESULTS

The mean diameter of the humeral entry was 4.0 mm (range, 3.4-5.1 mm) on the first CT scan, which increased to 5.5 mm (range, 3.2-7.2 mm) on the follow-up CT scan (P < .001). The mean diameter of the ulnar tunnel was 2.8 mm (range, 1.1-3.3 mm) on the first CT scan, which decreased to 1.6 mm (range, 0-4.3 mm) on the follow-up CT scan (P < .001). The between-group comparison revealed no differences in the changes in the diameter of the humeral and ulnar tunnels. A statistically significant correlation was not found between athletic performance measured by the Conway scale and the radiologic changes on CT evaluation (P = .182). Group A showed improvement in extension from 7° preoperatively to 1° postoperatively (P < .001) and in flexion from 126° preoperatively to 136° postoperatively (P < .001), while group NA did not achieve statistical significance in ROM improvement after the operation.

CONCLUSIONS

Humeral tunnel widening was commonly observed, while the ulnar tunnel was maintained or became narrowed conversely. The humeral tunnel placements did not affect tunnel changes after the surgical procedure; however, MUCL reconstruction with the anatomic location of the humeral tunnel yielded substantial improvement in elbow ROM.

In vivo heterotopic culturing of prefabricated tendon grafts with mechanical stimulation in a sheep model

BACKGROUND

The goal of this study is to investigate the biomechanical and histological properties of in vivo heterotopically prefabricated cruciate ligament replacement grafts with and without mechanical stimulation. The clinical goal is to heterotopically prefabricate a bone-tendon-bone graft for anterior cruciate ligament reconstruction, which allows rapid ingrowth and early full weight bearing.

METHODS

In a sheep model, eight quadriceps tendon grafts were harvested and introduced into culture chambers at their proximal and distal ends. In group S, four tendon-chamber constructs were mechanically stimulated by direct attachment to the quadriceps tendon and patella. In group NS, the same constructs were cultured without proximal attachment. All sheep were sacrificed six weeks postoperatively and the constructs were examined biomechanically and histologically. The healthy contralateral ACL and quadriceps tendon were used as controls.

RESULTS

Macroscopically, no obvious ossification could be observed at the ends of the tendon-chamber constructs six weeks postoperatively. Histologically, the tendon tissue from the mechanically stimulated constructs revealed higher counts of cells and capillaries. However, there was less regular cell distribution and collagen fiber orientation compared to the control group. In addition, osteoblasts and osteogenesis were observed in the prefabricated constructs both with and without mechanical stimulation. Biomechanically, there were no significant differences in stiffness, elongation and ultimate failure load between the groups.

CONCLUSION

In vivo heterotopic culture of prefabricated tendon grafts may have the potential to stimulate osteoblasts and induce osteogenesis. Future studies with longer follow-up and modifications of the surgical technique and culture conditions are desirable.

Increased lateral tibial posterior slope is related to tibial tunnel widening after primary ACL reconstruction

PURPOSE

The purpose of the study was to determine the influence of femoral and tibial bone morphology on the amount of femoral and tibial tunnel widening after primary anatomic ACL reconstruction. It was hypothesized that tibial and femoral bone morphology would be significantly correlated with tunnel widening after anatomic ACL reconstruction.

METHODS

Forty-nine consecutive patients (mean age 21.8 ± 8.1 years) who underwent primary single-bundle anatomic ACL reconstruction with hamstring autograft were enrolled. Two blinded observers measured the bone morphology of tibia and femur including, medial and lateral tibial posterior slope, medial and lateral tibial plateau width, medial and lateral femoral condyle width, femoral notch width, and bicondylar width on preoperative magnetic resonance imaging (MRI) scans. Tibial and femoral tunnel width at three points (aperture, mid-section, and exit) were measured on standard anteroposterior radiograph from 1 week and 1 year postoperatively (mean 12.5 ± 2 months). Tunnel width measurements at each point were compared between 1 week and 1 year to calculate percent of tunnel widening over time. Multivariable linear regression was used to analyze correlations between bone morphology and tunnel widening.

RESULT

Increase in lateral tibial posterior slope was the only independent bony morphology characteristics that was significantly correlated with an increased tibial tunnel exit widening (R = 0.58). For every degree increase in lateral tibial posterior slope, a 3.2% increase in tibial tunnel exit width was predicted (p = 0.003). Excellent inter-observer and intra-observer reliability were determined for the measurements (ICC = 0.91 and 0.88, respectively).

CONCLUSION

Increased lateral tibial posterior slope is an important preoperative anatomic factor that may predict tunnel widening at the tibial tunnel exit. In regard to clinical relevance, the results of this study suggest that lateral tibial posterior slope be measured preoperatively. In patients with increased lateral tibial posterior slope, more rigid graft fixation and a more conservative physical therapy regiment may be preferred. Level of evidence IV.

Tunnel widening after single- versus double-bundle anterior cruciate ligament reconstruction: a randomized 8-year follow-up study

OBJECTIVE

The purpose of this study was to compare the single-bundle (SB) and double-bundle (DB) surgical techniques for anterior cruciate ligament (ACL) reconstruction with regard to tunnel widening, isokinetic muscle strength, and clinical outcomes over an 8-year follow-up period.

METHODS

This study included 31 patients with ACL injury who underwent ACL reconstruction via the SB (n = 16) or the DB (n = 15) technique. Isokinetic and concentric strength measurements of the quadriceps and hamstring muscles were conducted at postoperative 6 months and postoperative 8 years, and 3D-CT scans of the knee joints were performed on the 2nd, 3rd and 6th month, and the 8th year postoperatively. Clinical evaluations were performed at 8 years postoperatively with the International Knee Documentation Committee (IKDC), Tegner, and Lysholm knee scoring systems.

RESULTS

There was marked widening of the parts of the femoral tunnel close to the knee joint in both the SD and the DB groups. There was no difference between the two groups in terms of clinical results and isometric muscle strength at postoperative 8 years; however, there was a significant difference between the preoperative and 6 months postoperative clinical and strength results in both group (P < 0.05). There was no difference between the groups in IKDC score, Lysholm score, Tegner activity scale, and anterior drawer test at postoperative 8 years. On evaluation of the anteromedial bundles alone, the DB group had greater widening than the SB group.

CONCLUSION

In this study, we have found that the tunnels continue to enlarge after 6 months. However, that has no impact in patients comfort and that did not made any change in our daily routine. On the other hand, we found that the reconstruction of the double-band ligament technique is useless for non-professional athletes.

Bone tunnel change develops within two weeks of double-bundle anterior cruciate ligament reconstruction using hamstring autograft: A comparison of different postoperative immobilization periods using computed tomography

BACKGROUND

The purpose of this study was to evaluate bone tunnel changes following anterior cruciate ligament (ACL) reconstruction during the early postoperative period using computed tomography (CT), and to understand the impact of postoperative immobilization on these changes.

METHODS

Twenty patients who underwent double-bundle ACL reconstruction using hamstring tendon autografts were included. We subcategorized patients into two groups: patients who underwent isolated ACL reconstruction and had three days of knee immobilization (Group A, n=10); and patients with concomitant meniscus injuries who underwent ACL reconstruction and meniscus repair simultaneously (Group B, n=10) had their knees immobilized for two weeks after surgery. Bone tunnel enlargement was evaluated using CT imaging at one to three days, two weeks, one month, three months and six months after surgery. The cross-sectional area of the femoral and tibial tunnels was measured, and enlargement rate was calculated. The tunnel center location at two weeks after surgery was also evaluated.

RESULTS

The mean cross-sectional area adjacent to the joint space of the femoral and tibial tunnels significantly increased immediately after surgery, especially in the first month (P<0.01). However, after one to six months they were not increased (P>0.01). There was no significant difference in tunnel enlargement rate between group A and B. Tunnel center location changed even in the first two weeks.

CONCLUSIONS

Bone tunnel enlargement following double-bundle ACL reconstruction occurred at an earlier time point after surgery than anticipated. Postoperative immobilization could not prevent bone tunnel enlargement, but might prevent tunnel migration.

Morphological changes in tibial tunnels after anatomic anterior cruciate ligament reconstruction with hamstring tendon graft

Background

Three-dimensional (3D) reconstructed computed tomography (CT) is crucial for the reliable and accurate evaluation of tunnel enlargement after anterior cruciate ligament (ACL) reconstruction. The purposes of this study were to evaluate the tibial tunnel enlargement at the tunnel aperture and inside the tunnel and to clarify the morphological change at the tunnel footprint 1 year after the anatomic triple-bundle (ATB) ACL reconstruction using 3D CT models.

Methods

Eighteen patients with unilateral ACL rupture were evaluated. The ATB ACL reconstruction with a semitendinosus tendon autograft was performed. 3D computer models of the tibia and the three tibial tunnels were reconstructed from CT data obtained 3 weeks and 1 year after surgery. The cross-sectional areas (CSAs) of the two anterior and the one posterior tunnels were measured at the tunnel aperture and 5 and 10 mm distal from the aperture and compared between the two periods. The locations of the center and the anterior, posterior, medial, and lateral edges of each tunnel footprint were also measured and compared between the two periods.

Results

The CSA of the posterior tunnel was significantly enlarged at the aperture by 40.4%, whereas that of the anterior tunnels did not change significantly, although the enlargement rate was 6.1%. On the other hand, the CSA was significantly reduced at 10 mm distal from the aperture in the anterior tunnels. The enlargement rate in the posterior tunnel was significantly greater than that in the anterior tunnels at the aperture. The center of the posterior tunnel footprint significantly shifted postero-laterally. The anterior and posterior edges of the posterior tunnel footprint demonstrated a significant posterior shift, while the lateral edge significantly shifted laterally. There was no significant shift of the center or all the edges of the anterior tunnels footprint.

Conclusions

The posterior tibial tunnel was significantly enlarged at the aperture by 40% with the morphological change in the postero-lateral direction reflected by the ACL fiber orientation 1 year after the ATB ACL reconstruction. The proper tibial tunnel location in the ACL reconstruction should be determined considering the tunnel enlargement in postero-lateral direction after surgery.

Bone Tunnel Enlargement after ACL Reconstruction with Hamstring Autograft Is Dependent on Original Bone Tunnel Diameter

Background  Bone tunnel enlargement is a well-established phenomenon following anterior cruciate ligament (ACL) reconstruction, and is related to soft tissue grafts, suspension fixation devices, and absorbable implants. Severe tunnel enlargement can lead to reconstruction failure. The correlation between bone tunnel enlargement following ACL reconstruction and original bone tunnel diameter has not been elucidated.

Purpose  To determine whether bone tunnel enlargement after ACL reconstruction with hamstring autograft is dependent on original tunnel diameter established during primary ACL reconstruction.

Materials and Methods  A retrospective review was conducted on 56 patients scheduled for ACL revision surgery who had undergone computed tomography (CT) scanning as part of their preoperative evaluation. All patients had undergone previous hamstring ACL reconstruction. Original femoral and tibial bone tunnel diameters were extracted from operative reports, and femoral and tibial bone tunnel enlargement was assessed on CT serial sections. The correlation between original tunnel diameter and bone tunnel enlargement was investigated using regression analysis.

Results  Mean tibial bone tunnel enlargement was significantly and inversely dependent on the original tibial bone tunnel diameter with a correlation coefficient of −0.55 per unit (7 mm = +1.93 mm, 8 mm = +1.43 mm, 9 mm = 0.83 mm, p  = 0.007). Thus, every additional increase (mm) in diameter of the original tibial bone tunnel reduces the extend of tunnel widening by 0.55 mm.

Conclusions  The results of this study indicate that tibial bone tunnel enlargement following ACL reconstruction is dependent on original tibial bone tunnel diameter with smaller diameter tunnels developing more tunnel enlargement than larger tunnels. The contributing factors remain unclear and need to be further investigated.

Clinical and Radiological Outcomes After Hamstring Anterior Cruciate Ligament Reconstructions: Comparison Between Fixed-Loop and Adjustable-Loop Cortical Suspension Devices

BACKGROUND

Few studies have compared clinical and radiological outcomes after hamstring anterior cruciate ligament (ACL) reconstruction with fixed-loop and adjustable-loop cortical suspension devices. Purpose/Hypothesis: The purpose of this retrospective study was to compare clinical outcomes and tunnel widening after hamstring ACL reconstructions with fixed- and adjustable-loop cortical suspension devices. The hypothesis was that compared with femoral graft fixation with the fixed-loop device, fixation with the adjustable-loop device would show similar clinical outcomes and would result in less tunnel widening after hamstring ACL reconstruction.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 117 consecutive patients underwent hamstring ACL reconstruction at a single institution. The fixed-loop cortical suspension device was used in 67 patients, and the adjustable-loop cortical suspension device was used in 50 patients. All patients were observed for a minimum of 2 years. Postoperative knee laxity was evaluated with the Lachman test, pivot-shift test, and KT-1000 arthrometer. Functional evaluations were performed by use of the Lysholm score and the Tegner activity scale. On anteroposterior (AP) and lateral radiographs, the measured diameters of the femoral tunnel at 1 year after surgery were compared with the diameter of the reamer used at surgery. The measured diameters of the tibial tunnel at 1 year after surgery were compared with those taken immediately after surgery.

RESULTS

The mean KT-1000 arthrometer laxity measurement was 1.5 ± 1.8 mm in the fixed-loop group and 1.2 ± 2.3 mm in the adjustable-loop group ( P = .530). Results of postoperative knee laxity evaluations and functional outcomes from both groups showed no statistically significant differences. However, the fixed-loop group showed significantly better stability in the pivot-shift test than did the adjustable-loop group ( P = .018). On AP radiographs, the mean diameter of the femoral and tibial tunnels increased by 42.2% ± 15.9% and 37.0% ± 17.8%, respectively, in the fixed-loop group and by 43.0% ± 15.4% and 36.8% ± 18.2% in the adjustable-loop group. On lateral radiographs, the mean diameter of the femoral and tibial tunnels increased by 38.1% ± 14.8% and 39.9% ± 13.8%, respectively, in the fixed-loop group and by 35.8% ± 12.2% and 38.1% ± 21.0% in the adjustable-loop group. No significant differences were found between the 2 groups in postoperative femoral and tibial tunnel widening on AP radiographs ( P = .801 and .951, respectively) or lateral radiographs ( P = .422 and .621, respectively).

CONCLUSION

Compared with femoral fixation by use of the fixed-loop device, femoral fixation by use of the adjustable-loop device showed similar clinical outcomes but did not reduce tunnel widening after hamstring ACL reconstructions.

Anterior cruciate ligament reconstruction tunnel size: causes of tunnel enlargement and implications for single versus two-stage revision reconstruction

Anterior cruciate ligament (ACL) reconstructions have increased over the past 25 years. The increased incidence of ACL reconstructions has translated into a larger number of graft failures and revision ACL procedures. It is important to understand the causes of graft failure when evaluating for a revision ACL reconstruction and to appreciate changes in tunnel anatomy over time prior to planning revision surgery. In this manuscript, tunnel size for ACL reconstruction and implications for single-stage versus two-stage revision ACL reconstruction will be discussed, as well as causes of tunnel enlargement, including mechanical and biological factors.

Bone tunnel enlargement following hamstring anterior cruciate ligament reconstruction: a comprehensive review

Nowadays, bone tunnel enlargement (BTE) after anterior cruciate ligament reconstruction is a well-known phenomenon. It has been identified, investigated and described by many authors during the last thirty years. Nevertheless, the etiology of bone tunnel enlargement still remains unclear. It is known that the causes are multifactorial and may include the surgical technique, the method of fixation, materials used, type of graft as well as biological factors. Due to the recent popularization of the use of hamstring grafts in anterior cruciate ligament reconstruction, the bone tunnel enlargement phenomenon is becoming increasingly common. In this review article, the authors focus on compiling current knowledge about the etiology, diagnosis, and the possibility of reducing the occurrence of this phenomenon by using the latest methods of supporting reconstruction surgery.

Tunnel widening prevention with the allo-Achilles tendon graft in anterior cruciate ligament reconstruction: Surgical tips and short term followup

BACKGROUND

Tunnel widening (TW) after anterior cruciate ligament (ACL) reconstruction can be a serious complication, and there is controversy over how to prevent it. This study aimed to suggest surgical approaches to prevent TW using an allo-Achilles tendon graft, and then to evaluate TW after these surgical tips were applied.

MATERIALS AND METHODS

Sixty two patients underwent ACL reconstruction with an allo-Achilles tendon graft. Four surgical approaches were used: Making a tibial tunnel by bone impaction, intraarticular reamer application, bone portion application for the femoral tunnel, and an additional bone plug application for the tibial tunnel. After more than 1-year, followup radiographs including anteroposterior and lateral views were taken in 29 patients encompassing thirty knees. The diameter of the tunnels at postoperation day 1 (POD1) and at followup was measured and compared.

RESULTS

In 18 knees (60%), there were no visible femoral tunnel margins on the radiographs at POD1 or followup. In the other 12 cases, which had visible femoral tunnel margins on followup radiographs, the mean femoral tunnel diameter was 8.6 mm. In the tibial tunnel, the mean diameters did not increase on all three levels (proximal, middle, and distal), and there was no statistically significant difference between the diameters at POD1 and followup.

CONCLUSION

The suggested tips for surgery involving an allo-Achilles tendon graft can effectively prevent TW after ACL reconstruction according to this case series. These surgical tips can prevent TW.

Morphological changes in femoral tunnels after anatomic anterior cruciate ligament reconstruction

PURPOSE

Few studies investigated the enlargement inside the tunnel as well as the morphological change at the aperture after anterior cruciate ligament (ACL) reconstruction, whereas the tunnel enlargement has been well documented. The purposes were to evaluate the change in the cross-sectional area along the femoral tunnel and to morphologically clarify the enlargement at the femoral tunnel aperture after anatomic triple-bundle (ATB) ACL reconstruction.

METHODS

The study included 15 patients with unilateral ACL rupture. ATB ACL reconstruction was performed using semitendinosus tendon autografts. Three-dimensional computer models of the femur and bone tunnels were reconstructed from computed tomography images obtained 3 weeks and 1 year postoperatively. The cross-sectional area at the aperture as well as inside the tunnel was compared between the two periods. Likewise, the location of tunnel walls and center in the tunnel footprint were evaluated.

RESULTS

The cross-sectional area enlarged by 22.7 % for anteromedial/intermediate graft (P = 0.002) and 28.6 % for posterolateral graft (P = 0.002) at the aperture, while decreased by 36.2 % at 10 mm from the aperture for anteromedial/intermediate graft (P = 0.004). Both the anterior and posterior walls shifted anteriorly, while the distal wall shifted distally in both tunnels. Consequently, the center in the footprint significantly shifted anteriorly (4.9-6.6 %) and distally (2.2-2.6 %) in both tunnels.

CONCLUSIONS

The femoral tunnel enlargement occurred at the aperture after ATB ACL reconstruction, but did not occur in the middle of the femoral tunnel. The morphology at the aperture changed with time after surgery as the tunnel walls translated anteriorly and distally.

LEVEL OF EVIDENCE

Case series, Level IV.

Anterior cruciate ligament reconstruction using a hamstring graft: a retrospective comparison of tunnel widening upon use of two different femoral fixation methods

PURPOSE

To compare femoral and tibial tunnel widening (TW) in patients undergoing anterior cruciate ligament (ACL) reconstruction using an interference screw (IS), or an EndoButton-Continuous Loop(®) on the femoral side, and an IS/staple on the tibial side.

METHODS

Between 2006 and 2009, at a single institution, 72 patients who underwent arthroscopic ACL reconstruction with quadrupled hamstring tendon grafting were retrospectively reviewed. Fixation was performed, and with the EndoButton-Continuous Loop(®) device (Group Ι) in 48 patients (mean age 29.1 ± 7.3 years) with a bioabsorbable IS (Group ΙΙ) in 24 patients (mean age 28.5 ± 8.4 years) on the femoral side. Evaluation included standardized anteroposterior (AP) and lateral radiography. The diameters of tunnels at the last follow-up visit (at a median time of 17 months postoperatively) were compared to those noted on radiographs taken 1 day postoperatively.

RESULTS

The two groups were similar in terms of age and gender distribution, the operated side, the size of the tunnel created, and the follow-up period (n.s.). Femoral TW at the proximal and middle levels (on both AP and lateral views) in Group ΙΙ was significantly greater than in Group Ι (p < 0.050 for all comparisons). No significant difference in femoral TW at the distal level was evident between the groups, and tibial TW at all levels was similar in both groups (n.s.).

CONCLUSION

Femoral TW is less after EndoButton-Continuous Loop(®) fixation and not reduced after IS fixation. Surgeons should be aware of TW when selecting a fixation device for hamstring graft.

LEVEL OF EVIDENCE

Therapeutic, retrospective comparative study, Level III.

Tibial and Femoral Tunnel Changes After ACL Reconstruction: A Prospective 2-Year Longitudinal MRI Study

BACKGROUND

Tunnel widening after anterior cruciate ligament reconstruction (ACL-R) is a well-accepted and frequent phenomenon, yet little is known regarding its origin or natural history.

PURPOSE

To prospectively evaluate the cross-sectional area (CSA) changes in tibial and femoral bone tunnels after ACL-R with serial MRI.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients underwent arthroscopic ACL-R with the same surgeon, surgical technique, and rehabilitation protocol. Each patient underwent preoperative dual-energy x-ray absorptiometry and clinical evaluation, as well as postoperative time zero MRI followed by subsequent MRI and clinical examination, including functional and subjective outcome tests, at 6, 12, 24, 52, and 104 weeks. Tibial and femoral tunnel CSA was measured on each MRI at tunnel aperture (ttA and ftA), midsection (ttM and ftM), and exit (ttE and ftE). Logistic regression modeling was used to examine the predictive value of demographic data and preoperative bone quality (as measured by dual-energy x-ray absorptiometry) on functional outcome scores, manual and instrumented laxity measurements, and changes in tunnel area over time.

RESULTS

Eighteen patients (including 12 men), mean age 35.5±8.7 years, underwent ACL-R. There was significant tunnel expansion at ttA and ftA sites 6 weeks postoperatively (P=.024 and .0045, respectively). Expansion continued for 24 weeks, with progressive tunnel narrowing thereafter. Average ttA CSA was significantly larger than ftA CSA at all times. The ttM significantly expanded after 6 weeks (P=.06); continued expansion to week 12 was followed by 21 months of reduction in tunnel diameter. The ftM and both ttE and ftE sites decreased in CSA over the 2 years. Median Lysholm and International Knee Documentation Committee scores significantly improved at final follow-up (P=.0083 and <.0001, respectively), and patients returned to preoperative activity levels. Pivot shift significantly decreased (P<.0001). Younger age (<30 years), male sex, and delayed ACL-R (>1 year from time of injury) predicted increased tunnel widening and accelerated expansion in CSA (P<.005).

CONCLUSION

Tunnel expansion after ACL-R occurs early and primarily at the tunnel apertures. Expansion may not affect clinical outcome. Younger age, male sex, and delay from injury to ACL-R may be potential risks for enlargement.

The Potentially Positive Role of PRPs in Preventing Femoral Tunnel Widening in ACL Reconstruction Surgery Using Hamstrings: A Clinical Study in 51 Patients

Purpose. In this study, the early and midterm clinical and radiological results of the anterior cruciate ligament (ACL) reconstruction surgery with or without the use of platelet rich plasma (PRP) focusing on the tunnel-widening phenomenon are evaluated. Methods. This is a double blind, prospective randomized study. 51 patients have completed the assigned protocol. Recruited individuals were divided into two groups: a group with and a group without the use of PRPs. Patients were assessed on the basis of MRI scans, which were performed early postoperatively and repeated at least one-year postoperatively. The diameter was measured at the entrance, at the bottom, and at the mid distance of the femoral tunnel. Results. Our study confirmed the existence of tunnel widening as a phenomenon. The morphology of the dilated tunnels was conical in both groups. There was a statistical significant difference in the mid distance of the tunnels between the two groups. This finding may support the role of a biologic response secondary to mechanical triggers. Conclusions. The use of RPRs in ACL reconstruction surgery remains a safe option that could potentially eliminate the biologic triggers of tunnel enlargement. The role of mechanical factors, however, remains important.

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.

In vivo three-dimensional imaging analysis of femoral and tibial tunnel locations in single and double bundle anterior cruciate ligament reconstructions

BACKGROUND

Anatomic footprint restoration of anterior cruciate ligament (ACL) is recommended during reconstruction surgery. The purpose of this study was to compare and analyze the femoral and tibial tunnel positions of transtibial single bundle (SB) and transportal double bundle (DB) ACL reconstruction using three-dimensional computed tomography (3D-CT).

METHODS

In this study, 26 patients who underwent transtibial SB ACL reconstruction and 27 patients with transportal DB ACL reconstruction using hamstring autograft. 3D-CTs were taken within 1 week after the operation. The obtained digital images were then imported into the commercial package Geomagic Studio v10.0. The femoral tunnel positions were evaluated using the quadrant method. The mean, standard deviation, standard error, minimum, maximum, and 95% confidence interval values were determined for each measurement.

RESULTS

The femoral tunnel for the SB technique was located 35.07% ± 5.33% in depth and 16.62% ± 4.99% in height. The anteromedial (AM) and posterolateral (PL) tunnel of DB technique was located 30.48% ± 5.02% in depth, 17.12% ± 5.84% in height and 34.76% ± 5.87% in depth, 45.55% ± 6.88% in height, respectively. The tibial tunnel with the SB technique was located 45.43% ± 4.81% from the anterior margin and 47.62% ± 2.51% from the medial tibial articular margin. The AM and PL tunnel of the DB technique was located 33.76% ± 7.83% from the anterior margin, 45.56% ± 2.71% from the medial tibial articular margin and 53.19% ± 3.74% from the anterior margin, 46.00% ± 2.48% from the medial tibial articular margin, respectively. The tibial tunnel position with the transtibial SB technique was located between the AM and PL tunnel positions formed with the transportal DB technique.

CONCLUSIONS

Using the 3D-CT measuring method, the location of the tibia tunnel was between the AM and PL footprints, but the center of the femoral tunnel was at more shallow position from the AM bundle footprint when ACL reconstruction was performed by the transtibial SB technique.

Femoral tunnel enlargement after medial patellofemoral ligament reconstruction: prevalence, risk factors, and clinical effect

BACKGROUND

In recent years, significantly more attention has been focused on the role of the medial patellofemoral ligament (MPFL) in patellar stability, and MPFL reconstruction has become a mainstay of surgical treatment of episodic patellar dislocations. Although previously described in detail after reconstruction of the anterior cruciate ligament, tunnel enlargement has not been investigated after MPFL reconstruction.

HYPOTHESES

(1) Femoral tunnel enlargement occurs after MPFL reconstruction. (2) Patella alta, trochlear dysplasia, and tunnel malposition are risk factors for tunnel enlargement. (3) The presence of tunnel enlargement is not associated with recurrent dislocations or poorer patient-reported outcome scores after MPFL reconstruction.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Fifty-five of 59 knees treated for episodic patellar dislocations with MPFL reconstruction between 2005 and 2010 were evaluated at 1 year postoperatively for the presence of tunnel enlargement on lateral radiographs. Tunnel enlargement was defined as a tunnel area greater than 2 times that of the original tunnel. Knees with tunnel enlargement at 1 year were compared with those without tunnel enlargement. Patients were assessed for recurrent subluxations or dislocations at a mean of 3 years postoperatively, and patient-reported outcome scores were assessed in a subset of patients at a mean of 3.7 years postoperatively.

RESULTS

Tunnel enlargement was noted in 23 knees (41.8%). No differences in patient age or body mass index were noted between the 2 groups. The mean patellar height was significantly higher in the enlarged tunnel group (P = .03). A higher prevalence of trochlear dysplasia or tunnel malposition was not demonstrated in the enlarged tunnel group. Patient-reported outcome scores and the risk of recurrent patellar instability were equal in the 2 groups.

CONCLUSION

Femoral tunnel enlargement after MPFL reconstruction is common, with patients with patella alta at an increased risk. The influence of tunnel malposition and trochlear dysplasia on this condition requires further research. Recurrent instability and patient-reported outcome scores are not affected by tunnel enlargement.

Effects of tunnel dilation and interference screw position on the biomechanical properties of tendon graft fixation for anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to evaluate the effects of screw position and compaction of the bone tunnel on the strength of the flexor tendon graft after fixation using interference screws.

METHODS

Forty fresh-frozen porcine tibias were used for this study. The digital flexor tendons were folded into a quadrupled graft measuring 9 mm in diameter. In the extraction-drilling group, tibial bone tunnels were drilled with a conventional cannulated 9-mm drill bit in a single step. In the compaction-drilling group, bone tunnels were drilled using a cannulated 7-mm drill bit and were expanded to a final diameter of 9 mm in 0.5-mm increments by placement of dilators with increasing diameter. The grafts were fixed using 9 × 30-mm titanium screws in central and eccentric positions. Specimens underwent a cyclic-loading test, and the surviving specimens were then loaded until failure.

RESULTS

Graft displacement after 1,500 loading cycles occurred significantly more often in the extraction-drilling group with eccentric screw placement than in the groups of extraction-drilling (P < .05) and compaction-drilling (P < .01) with central screw placement. There were no statistically significant differences for the maximum screw insertion torque, maximum load at failure, or stiffness among the 4 groups. One strand of the quadrupled tendon grafts showed partial injury during screw insertion in 3 (30%) and 4 (40%) of 10 specimens of the extraction-drilling and compaction-drilling groups with central screw placement, respectively.

CONCLUSIONS

Central screw placement significantly decreased the displacement of the tendon graft in comparison with eccentric screw placement in the extraction-drilling condition. Compaction of the bone tunnel walls by serial dilation in a central screw position did not increase the strength of interference screw fixation of a soft tissue graft.

CLINICAL RELEVANCE

When using the extraction method and fixing the graft in an eccentric position, it is advisable to provide additional fixation outside the tunnel to prevent slippage of the graft.

Platelet-rich plasma: does it help reduce tunnel widening after ACL reconstruction?

PURPOSE

The purpose of this study was to evaluate the efficacy of platelet-rich plasma (PRP) in reducing femoral and tibial tunnel enlargement in patients operated on for anterior cruciate ligament reconstruction with hamstrings.

METHODS

Forty male patients, in which both femoral and tibial 9-mm tunnels were performed because of the graft size, were enrolled in this prospective study. They were randomly assigned to group A (20 patients, PRP group) and group B (20 patients, control group). All patients were followed up at a median of 14.7 months (range 10-16 months), with a physical examination, the Tegner, Lysholm and objective IKDC scoring scales, and with the KT-1000 arthrometer. Moreover, they underwent a CT evaluation in order to assess the amount of tunnel enlargement.

RESULTS

Femoral tunnel diameter increased from 9.0 ± 0.1 mm to 9.8 ± 0.3 mm in group A (p = 0.032) and from 9.0 ± 0.1 mm to 9.4 ± 0.5 mm in group B (p = 0.043). Tibial tunnel diameter increased from 9.0 ± 0.2 mm to 10.9 ± 0.2 mm in group A (p = 0.029) and from 9.1 ± 0.1 mm to 10.1 ± 0.4 mm in group B (p = 0.028). Physical examination as well as the evaluation scales used showed no differences between the two groups.

CONCLUSIONS

The use of PRP does not seem to be effective in preventing tunnel enlargement.

ACL graft healing and biologics

Operative reconstruction of a torn anterior cruciate ligament (ACL) has become the most broadly accepted treatment. An important, but underreported, outcome of ACL reconstruction is graft failure, which poses a challenge for the orthopedic surgeon. An understanding of the tendon-bone healing and the intra-articular ligamentization process is crucial for orthopedic surgeons to make appropriate graft choices and to be able to initiate optimal rehabilitation protocols after surgical ACL reconstruction. This article focuses on the current understanding of the tendon-to-bone healing process for both autografts and allografts and discusses strategies to biologically augment healing.

Tibial tunnel widening after hamstring anterior cruciate ligament reconstructions: comparison between Rigidfix and Bio-TransFix

BACKGROUND

There is no study comparing tibial tunnel widening after hamstring anterior cruciate ligament (ACL) reconstructions between RigidFix(r) and Bio-TransFix(r).

METHODS

Hamstring ACL reconstructions using RigidFix(r) in 56 patients and Bio-TransFix(r) in 41 with a minimum of 2years postoperative evaluation were reviewed. Tibial fixation was performed using Intrafix in both groups. On the anterior-posterior (AP) and lateral radiographs, the diameter of the tibial tunnel was measured at proximal, middle, and distal positions. Postoperative laxity evaluations were performed using Lachman test, pivot-shift test, and instrumented laxity testing using the KT-1000 arthrometer.

RESULTS

On the AP and lateral radiographs, the average diameter of the tibial tunnel in the Bio-TransFix(r) group significantly increased after 6months compared to the immediate postoperative measurement (p=0.002 and p=0.002, respectively). However, the average diameter of the tibial tunnel in the RigidFix(r) group did not increase after 6months compared to the immediate postoperative measurement. Tunnel widening at 12months postoperatively in the Bio-TransFix(r) group was significantly more than that of the RigidFix(r) group on AP and lateral radiographs (p=0.012 and 0.016, respectively). Tunnel widening at 24months postoperatively showed a significant difference between the two groups (p=0.000 and 0.000, respectively). Fifteen patients (36.6%) in the Bio-TransFix(r) group and 15 patients (26.8%) in the RigidFix(r) group showed tunnel widening. There were no significant differences in results of the Lachman and pivot-shift tests, and mean KT-1000 measurement between the two groups.

CONCLUSION

The Bio-TransFix(r) group showed progressive tibial tunnel widening after 6months postoperatively but no clinical signs of instability.

LEVEL OF EVIDENCE

Level III.

Design Considerations for a Prosthetic Anterior Cruciate Ligament

Anterior cruciate ligament (ACL) tearing is a common knee injury often requiring reconstruction with an autograft or an allograft. A prosthetic ligament replacement with off-the-shelf availability could potentially provide significant advantages over the current options for both patients and surgeons. Limitations of previous prosthetics include lack of biocompatibility and susceptibility to fatigue, creep, and failure of bony incorporation. This paper describes design considerations and possible improvements for the next generation prosthetic ACL. Design controls, as mandated by the FDA, are a systematic set of practices within the design and development process used to ensure that a new medical device meets the needs of the intended users. The specified requirements, called the design inputs, for a prosthetic ACL are discussed pertaining to material and structural properties, resistance to creep and fatigue, ability to support secure initial fixation, biocompatibility, and long-term osseointegration. Design innovations to satisfy the design inputs are discussed with regards to material selection, textile pattern, bone tunnel features, and short term fixation. A risk analysis is presented along with descriptions of proposed testing. Design control methodology and tissue engineering may be used to develop a next generation prosthetic ligament, solving multiple problems, simultaneously, on a holistic level, providing major improvements over earlier devices and current treatment options.

High incidence of tunnel widening after anterior cruciate ligament reconstruction with transtibial femoral tunnel placement

BACKGROUND

This study evaluated the incidence, amount, morphology and clinical significance of bone tunnel widening (TW) at a mean 5-year period after anterior cruciate ligament reconstruction (ACLR) with a transtibial drilling technique.

METHODS

Fifty-nine patients undergoing primary ACLR using quadrupled hamstring autografts, biodegradable transfemoral pins for femoral-sided and 2-mm oversized interference screws for tibial-sided graft fixation were followed up at a mean 61 months postoperatively. Patients were examined clinically and by MRI. Tunnel cross-sectional areas (CSA) were related to drill diameters, which were significantly correlated with radiographic tunnel sizes. Tunnel morphologies were assessed and their positions determined using an anatomical coordinate system.

RESULTS

CSA had more than doubled in all segments measured (p < 0.0001) except at the femoral notch level. Greatest CSA increases were found at the femoral graft suspension point (122 %) and at the central tibial tunnel segment (134 %). 54 (92) and 56 (95 %) patients had significant TW, i.e., CSA increase of more than 50 %, in at least one tunnel segment femorally and tibially. Four different tunnel morphologies were observed, of which the linear type was most often encountered on either side. Mean side-to-side difference in anterior-posterior laxity was 1.0 ± 1.4 mm, while Lysholm, IKDC and Tegner activity scores were 90 ± 12, 84 ± 15 and 4 (1-9); clinical outcomes were not found to be correlated with tunnel sizes and morphologies as were tunnel positions and tunnel sizes.

CONCLUSIONS

This study demonstrates that considerable TW occurs in virtually all patients in the mid term after ACLR using a transtibial drilling technique with 'high' femoral tunnel positions. Yet, neither amount nor morphology or tunnel position does affect knee stability or function.

Effect of PEEK polymer on tunnel widening after hamstring ACL reconstruction

The purpose of this study was to evaluate the effect of the AperFix device (Cayenne Medical, Inc, Scottsdale, Arizona), composed of polyetheretherketone (PEEK) polymer, on tunnel widening after hamstring anterior cruciate ligament (ACL) reconstruction as compared with 2 other fixation devices: the TransFix (Arthrex, Inc, Naples, Florida) and the EndoButton (Smith & Nephew Endoscopy, Mansfield, Massachusetts). Sixty-seven patients with isolated total ACL ruptures who underwent arthroscopically assisted reconstruction using hamstring autografts at the authors' institution were included in the study. Patients were assigned into 1 of 3 groups in a nonrandomized fashion: AperFix (n=18), TransFix (n=29), and EndoButton (n=20). Mean follow-up was 30 months. Tunnel widening measurements were performed on anteroposterior and lateral digital plain radiographs taken in postoperative week 1 and at final follow-up. Laxity testing, Lysholm scoring, and arthrometric evaluation were performed.All 3 graft fixation devices resulted in significant tunnel widening in both tibial and femoral tunnels at final follow-up when compared with the immediate postoperative period. Tunnel widening between groups was not significantly different in terms of coronal and sagittal femoral tunnel diameters. Tibial tunnel diameter increase in the sagittal plane in the EndoButton group was significantly smaller than that in the TransFix and AperFix groups. No correlation was found between the amount of tunnel enlargement and clinical outcomes of ACL surgery. This study's findings suggest that tunnel enlargement after ACL reconstruction is influenced by the type of graft fixation on the tibial side irrespective of clinical outcome, and PEEK polymer does not have an effect on tunnel widening after hamstring ACL reconstruction.

In vivo graft tension in anatomic double-bundle anterior cruciate ligament reconstruction during active leg-raising motion with the knee splinted

PURPOSE

The purpose of this study was to measure the in vivo graft tension in anatomic 2-bundle anterior cruciate ligament (ACL) reconstruction during active leg-raising exercise with the knee immobilized.

METHODS

Anatomic double-bundle ACL reconstruction was performed with autogenous semitendinosus tendons in 7 patients while under general anesthesia. Two grafts were fixed with 2 EndoButton-CL devices (Smith & Nephew Endoscopy, Andover, MA) on the femur and were temporarily fixed to 2 tension-adjustable force gauges on the anterior tibial cortex. Then, a knee brace in semi-flexion was put around the knee, and 10 N of initial tension was applied to each graft at 20° of flexion. The tension on the anteromedial (AM) and posterolateral (PL) grafts was continuously measured during active leg-raising motion with the knee immobilized after patients had awoken from anesthesia. Then, the tension measurement was repeated during active leg-raising motion with the knee immobilized while a 2-kg weight was fitted around the ankle.

RESULTS

In situ graft tension during active leg-raising motion with a knee brace was 10.9 ± 4.0 N for the AM graft and 8.6 ± 5.1 N for the PL graft, whereas the tension with a 2-kg weight around the ankle was 10.9 ± 3.4 N for the AM graft and 9.9 ± 3.6 N for the PL graft. There was no significant difference between each graft in the 2 motions with a paired t test.

CONCLUSIONS

Graft tension with the knee immobilized with a semi-flexed knee brace during active leg-raising motion was 19.5 N with no weight and 20.8 N with additional weight, both of which were almost equal to the initial graft tension at the time of fixation at 20°. Thus the leg-raising exercise can be recommended as safe when a semi-flexed knee brace is worn after ACL reconstruction.

CLINICAL RELEVANCE

These findings will help to plan postoperative rehabilitation programs with security.

A new technique in double-bundle anterior cruciate ligament reconstruction using implant-free femoral fixation

PURPOSE

The study is a prospective case-series analysis to demonstrate a new double bundle technique for anterior cruciate ligament (ACL) reconstruction with the use of hamstring tendons through a single tibial tunnel, a double femoral socket with implant-free femoral fixation and interference screw for tibial fixation.

MATERIALS AND METHODS

Twenty-one patients were treated with the same technique. Hamstring tendons were not removed from the tibial side, and using a single tibial and a double femoral tunnel of 8 and 6 mm, respectively, anatomic ACL reconstruction was performed. Graft passage was performed from the tibial side to the posterolateral femoral tunnel and was looped back to the anteromedial femoral tunnel to be fixed on the tibial tunnel with an interference screw and additional extracortical fixation. Follow-up of the study group was performed for a two-year period, documenting standard clinical and radiographic parameters.

RESULTS

Post-operative follow-up (mean 24 months) revealed radiological widening of tibial tunnel (mean 133.6%) in all patients and minor femoral tunnels widening (119.4% and 117.5%). Clinical evaluation showed no signs of instability, and knee evaluation using the IKDC score was performed.

CONCLUSION

The manuscript describes a novel technique in ACL reconstruction, and reports the radiographic results of tunnel widening and clinical scores. Implant-free femoral fixation led to minor tunnel widening similar to previously published data. Further studies need to be performed to compare the long-term results with different published techniques of cost-effective implant-free ACL reconstruction.

[Biodegradable screw versus a press-fit bone plug fixation for ACL reconstruction: a prospective randomized study]

BACKGROUND

Press-fit fixation of a tendon graft has been advocated in order to achieve tendon to bone healing.

HYPOTHESIS

Fixation of a tendon graft with a porous bone scaffold limits bone tunnel enlargement compared with a biodegradable interference screw fixation.

METHODS

Between 2005 and 2006, 20 patients (17 men, 3 women) were enrolled in this study for primary reconstruction of the ACL. Patients were randomized to either obtain graft fixation in the tibial tunnel by means of an interference screw (I) or a press-fit fixation with a porous bone cylinder (P). Three months after surgery, a CT scan of the knee was performed and tunnel enlargement was analysed in the coronal and sagittal planes for the proximal, middle and distal thirds of the tunnel. After 6 months, 1 and 2 years, International Knee Documentation Committee (IKDC), Tegner and Lysholm scores of both groups were compared.

RESULTS

The bone tunnel enlargement was 106.9±10.9% for group P and 121.9±9.0% for group I (P<0.02) in the AP plane and 102.8±15.2% vs 121.5±10.1% in the coronal plane (P<0.01). IKDC, Tegner, and Lysholm scores improved in both groups from pre- to postoperative assessment without significant differences between the two groups. There was a trend to higher knee stability in group P after 3 months (0.6±1.4 mm vs 1.81±.5 mm, P=0.08).

CONCLUSIONS

Both interference screw and a press-fit fixation lead to a high number of good or very good outcomes after ACL reconstruction. Tibial press-fit fixation decreases the amount of proximal bone tunnel enlargement. Press-fit fixation decreases the amount of proximal bone tunnel enlargement and improves bone to tendon contact.

Effect of varying the length of soft-tissue grafts in the tibial tunnel in a canine anterior cruciate ligament reconstruction model

PURPOSE

To investigate the effect of graft length within the bone tunnel on tendon-bone healing at an early stage after anterior cruciate ligament (ACL) reconstruction using Achilles tendon autograft in a canine model.

METHODS

We divided 40 adult dogs into 4 groups (n = 10 per group). Each dog underwent ACL reconstruction with Achilles tendon autograft in both knees. In groups I, II, III, and IV, the graft length within the tibia tunnel was 5 mm, 10 mm, 15 mm, and 20 mm, respectively. Five dogs in each group were killed 6 and 12 weeks postoperatively, with 3 knees used for histologic observation and 7 knees for mechanical testing.

RESULTS

Six weeks after surgery, the histologic scores in group I were lower than those in the other groups (P < .01) and those in group II were lower than those in group III and group IV (P < .01). However, there was no difference between group III and group IV (P > .05). At 12 weeks, there were no significant differences in histologic scores between groups (P > .05). The biomechanical test at 6 weeks showed that the mean graft pullout strength improved from group I to group IV. Except between groups III and IV (P = .142), there was a significant difference in the pullout strength among other groups. At week 12, the failure points were in the midsubstance of most specimens and more tibial-side graft pullout was found in group I than in the other groups (P < .001).

CONCLUSIONS

The histologic maturity and biomechanical strength of the tendon-bone junction after ACL reconstruction in dogs will be delayed at an early stage if the graft length in the bone tunnel is less than 15 mm.

CLINICAL RELEVANCE

There is a minimal acceptable amount of intratunnel tendon graft to allow satisfactory early tendon-bone healing, and attempts to save tendon graft length that lower the amount of intratunnel graft below a minimum of 15 mm should be avoided.

Tunnel widening after anterior cruciate ligament reconstruction: a prospective randomized computed tomography--based study comparing 2 different femoral fixation methods for hamstring graft

PURPOSE

We prospectively sought to compare the incidence and properties of tunnel widening in patients undergoing anterior cruciate ligament reconstruction with quadrupled hamstring graft by use of either EndoButton CL (Smith & Nephew Endoscopy, Andover, MA) or Transfix (Arthrex, Naples, FL) on the femoral side with a bioabsorbable interference screw in the tibial tunnel by computed tomography scan.

METHODS

We included 34 patients in the study and randomized them into 2 groups--EndoButton and Transfix groups. An anteromedial portal technique was used to create the femoral tunnels in the EndoButton group, whereas a transtibial technique was used in the Transfix group. A bioabsorbable screw was used on the tibial side in both groups. Thirty patients completed the study protocol, and assessment was done at regular intervals until 12 months of follow-up was reached. The patients underwent computed tomography scans at 2 weeks, 3 months, and 6 months postoperatively. The diameters of the tunnels were measured perpendicular to the long axis of the tunnels on oblique coronal and oblique sagittal planes at 3 levels: aperture, midway, and suspension point. We performed functional scoring with the International Knee Documentation Committee 2000 Subjective Knee Evaluation score and Lysholm score.

RESULTS

Femoral tunnel widening at the aperture and at midway was significantly greater in the EndoButton group compared with the Transfix group. A decrease in the loop length in the EndoButton group was associated with lesser tunnel widening, although this was not found to be statistically significant with the numbers available. A trend toward decreased tunnel widening at the aperture on the tibial side was observed when the tip of the screw was 10 to 15 mm away from the aperture.

CONCLUSIONS

Femoral tunnel widening was significantly less in the Transfix group compared with the EndoButton group.

LEVEL OF EVIDENCE

Level II, prospective comparative study.