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

Anterior cruciate ligament femoral side retained stump technique reduces enlargement of the femoral bone tunnel after anterior cruciate ligament reconstruction

BACKGROUND

Enlargement of the bone tunnel has become an unavoidable early complication after anterior cruciate ligament (ACL) reconstruction, whether it is a single or double-bundle ACL reconstruction. Preservation of the ACL stump in ACL reconstruction reduces enlargement of the bone tunnel. The purpose of this study was to investigate the question of whether single-bundle ACL reconstruction using the ACL femoral side retained stump technique reduces enlargement of the femoral tunnel.

METHODS

Forty patients who underwent single-bundle reconstruction of the ACL were included in this study. The patients were categorized into a Remnant preservation group (Group R) and the Non-remnant preservation group (Group N). In the Remnant preservation group, a high-flexion femoral side retained stump technique was used intraoperatively for the establishment of the femoral side bone tunnel, and in the Non-remnant preservation group, the conventional femoral positioning method was used (we used a femoral positioning drill for localization and drilling of the femoral bone tunnel), and MRI of the operated knee joints was performed at 6 months postoperatively. We measured the internal diameter of the femoral bone tunnel at 5 mm from the intra-articular outlet of the femoral bone tunnel on an MRI scan image perpendicular to the femoral bone tunnel. The size of the tunnel was compared between the intraoperative drilling of the bone tunnel and the size of the bone tunnel at 6 months postoperatively. Postoperative clinical assessment was Lysholm score.

RESULTS

After a 6-month follow-up of 40 patients, the diameter of the femoral tunnel at a distance of 5 mm from the inner opening of the femoral tunnel was 10.96 ± 0.67 mm and 10.11 ± 0.62 mm in patients of group N and group R, respectively, and the difference was statistically significant (P < 0.05).The diameter of the femoral tunnel at 6 months postoperatively in group N and group R compared to the intraoperative bone tunnel increased by 2.58 ± 0.24 mm and 1.94 ± 0.31 mm, and the difference was statistically significant (P < 0.05).The femoral tunnel enlargement rates of group N and group R were 30.94 ± 3.00% and 24.02 ± 5.10%, respectively, and the differences were significant (P < 0.05).

CONCLUSION

ACL femoral side retained stump technique does not sacrifice the ideal location of the femoral tunnel and is able to preserve the possible benefits of the ACL stump: reduced femoral tunnel enlargement.

Five-Strand Versus Four-Strand Hamstring Autografts in Anterior Cruciate Ligament Reconstruction-A Prospective Randomized Controlled Study

PURPOSE

To compare the clinical outcomes of the routine use of 5-strand hamstring grafts (where possible) with those of 4-strand grafts in primary anterior cruciate ligament (ACL) reconstruction.

METHODS

A total of 64 patients were enrolled in a prospective randomized controlled study comparing the use of 5-strand and 4-strand semitendinosus-gracilis autografts in single bundle ACL reconstruction (n = 32 in each group). Four participants in each group were lost to follow-up and were excluded from the outcome analysis. The outcomes of 28 patients in the 5-strand group and 28 patients in the 4-strand group were analyzed. The diameters of all grafts were measured intraoperatively. Patients were assessed postoperatively at 2 years with objective assessments (anterior knee laxity using the KT-2000 arthrometer, Lachman test, pivot-shift test, hop test) and patient-reported outcome scores (Lysholm knee score, Knee Injury and Osteoarthritis Outcome Score, International Knee Documentation Committee subjective knee score, SF-36 physical and mental components, Tegner activity scale). Postoperative graft ruptures were also noted.

RESULTS

There were improvements in all outcome measures postoperatively regardless of the number of graft strands. When we compared the study and control groups, there were no significant differences in all subjective and objective outcome measures except the Knee Injury and Osteoarthritis Outcome Score symptoms score (5-strand group 93.3 ± 9.2 vs 4-strand group 86.2 ± 14.7, P = .04). The KT-2000 side-to-side difference was 2.79 ± 2.11 mm in the 5-strand group and 2.54 ± 1.75 mm in the 4-strand group (P = .63). The 5-strand study group had 2 graft ruptures at 1 year, whereas the 4-strand control group had one partial graft rupture at 6 months.

CONCLUSIONS

At 2-year follow-up, the routine use of the 5-strand hamstring tendon autograft was not superior to that of the quadrupled or 4-strand graft in primary ACL reconstruction.

LEVEL OF EVIDENCE

Level I, prospective randomized controlled trial.

Biomechanical Properties of Small-Size Hamstring Autografts

Purpose

To evaluate small-size hamstring (HS) autografts for biomechanical properties and determine a threshold diameter necessary for appropriate reconstruction.

Methods

In a controlled laboratory setting, biomechanical testing was performed upon 15 hamstring autografts. The grafts were divided into three groups by diameter, with five grafts each at diameter sizes of 6, 7, and 8 mm. Testing of the specimens was performed using an MTS 858 (Materials Testing System, Eden Prairie, MN). We determined load to failure by looking at the maximum load as well as the stiffness of the graft. Statistical analysis was performed via analysis of variance (ANOVA) testing with Tukey's post-hoc test and P-values set at 0.05.

Results

There was a significant difference in ultimate tensile strength for the different size grafts: 1990 +/- 302.42 N for 6 mm grafts (n=5), 2179 +/- 685.36 N for the 7 mm grafts (n=5), and 3074 +/- 781 N for 8 mm grafts (n=5). This was statistically significant for the group overall (p=0.039), as well as between the 6 mm and 8 mm grafts (p=0.044). Graft stiffness for the 6 mm grafts was 317 +/- 85 N (n=5), 288.6 +/- 66 for 7 mm grafts (n=5), and 428.053 +/- 83 for 8 mm grafts (n=5). This achieved statistical significance for the group overall (p =0.037) as well as between the 8 mm and 7 mm grafts.

Conclusions

The biomechanical data presented here demonstrate that graft diameter is highly correlated with ultimate tensile strength and stiffness.

Clinical relevance

When viewing this biomechanical data in conjunction with prior clinical data, consideration should be given for the supplementation of an HS autograft as the size decreases below 8 mm.

Influence of three different fixation methods on femoral tunnel widening in ACL reconstructed patients evaluated using computed tomography (CT) scan

PURPOSE

To evaluate femoral tunnel widening in young and active patients undergoing ACL reconstruction with quadrupled hamstring graft with fixation on tibial side performed with a Bioscrew while femoral fixation performed with either a Tight rope Reverse Threaded (RT) or Transfix or another Bioscrew using CT scan.

MATERIAL AND METHOD

A total of 100 consecutive patients underwent single-bundle ACL reconstruction from January 2008 to March 2012. Eighty-six out of these were available with us till the final follow-up. Only 20-40-year-old males with unilateral ACL rupture less than a year old, diagnosed clinically and confirmed radiologically by magnetic resonance imaging, were selected for the study. All patients were evaluated clinically as well as radiologically at follow-up of 2 weeks, 1 month, 3 months, 6 months, 1 year and every 6 months thereafter. CT scans were performed at 2 weeks, 6 months, and 1 year postoperatively. The data acquired at the second week were considered as baseline data and were used for comparison with the data acquired at 6 months and 1 year.

RESULTS

The dilatation at the aperture was significantly more in the Tight rope RT group as compared to the other two groups (p value 0.019 and 0.021 for sagittal and coronal images, respectively).

CONCLUSION

There is no significant difference between the three different fixation modes in context of tunnel enlargement except with Tight rope RT device which leads to statistically significant dilatation at aperture. Future studies with longer follow-up are required to evaluate its clinical implications.

Long-Term Results of Anterior Cruciate Ligament Reconstruction Using Hamstring Grafts and the Outside-In Technique: A Comparison Between 5- and 15-Year Follow-up

Background:

Increased femoral tunnel widening and weakness of the hamstring muscles postoperatively have been described as potential adverse events after anterior cruciate ligament (ACL) reconstruction (ACLR) with a hamstring graft. Meniscectomy and cartilage lesions are important factors for the development of degenerative osteoarthritis.

Purpose:

To compare 15-year follow-up data with 5-year follow-up data from the same cohort of patients after ACLR with a hamstring autograft using an outside-in technique.

Study Design:

Case series; Level of evidence, 4.

Methods:

A total of 72 patients who underwent anatomic ACLR with a quadruple hamstring graft and an outside-in technique were selected for this prospective study. Patients were reviewed at a minimum follow-up of 15 years. Results were compared with the same series of patients previously reviewed at 5 years after surgery. Lysholm, International Knee Documentation Committee (IKDC), and Tegner scores as well as KT-1000 arthrometer measurements were obtained at final follow-up. Comparative weightbearing radiographs were obtained and analyzed according to the Fairbank, Kellgren-Lawrence, and IKDC classifications and used for the tunnel evaluation.

Results:

No significant difference was detected on the subjective evaluation. Objectively, patients categorized as A or B according to the IKDC score were not significantly different at 5 and 15 years (P < .01). A KT-1000 arthrometer side-to-side manual maximum difference >5 mm, a pivot shift >2+, any giving-way episode, and ACL revision surgery were considered as failures, and these were noted in 6 patients at 5 years and 6 patients at 15 years. The radiological evaluation at 15 years showed a higher rate of osteoarthritis in 2 of 3 radiological scales used in the study compared with results at 5-year follow-up (P < .01). At 15-year follow-up, there was a statistically significant reduction in the mean tibial tunnel diameter (P < .01).

Conclusion:

Endoscopic single-bundle ACLR using hamstring grafts and an outside-in technique demonstrated good results at 15-year follow-up in terms of subjective, objective, and radiographic evaluations. As compared with 5-year follow-up, clinical results remained stable both subjectively and objectively. However, a progression of osteoarthritis changes was observed, especially in patients in whom meniscectomy had been performed.

Ultrasound-Mediated Gene Delivery Enhances Tendon Allograft Integration in Mini-Pig Ligament Reconstruction

Ligament injuries occur frequently, substantially hindering routine daily activities and sports participation in patients. Surgical reconstruction using autogenous or allogeneic tissues is the gold standard treatment for ligament injuries. Although surgeons routinely perform ligament reconstructions, the integrity of these reconstructions largely depends on adequate biological healing of the interface between the ligament graft and the bone. We hypothesized that localized ultrasound-mediated, microbubble-enhanced therapeutic gene delivery to endogenous stem cells would lead to significantly improved ligament graft integration. To test this hypothesis, an anterior cruciate ligament reconstruction procedure was performed in Yucatan mini-pigs. A collagen scaffold was implanted in the reconstruction sites to facilitate recruitment of endogenous mesenchymal stem cells. Ultrasound-mediated reporter gene delivery successfully transfected 40% of cells recruited to the reconstruction sites. When BMP-6 encoding DNA was delivered, BMP-6 expression in the reconstruction sites was significantly enhanced. Micro-computed tomography and biomechanical analyses showed that ultrasound-mediated BMP-6 gene delivery led to significantly enhanced osteointegration in all animals 8 weeks after surgery. Collectively, these findings demonstrate that ultrasound-mediated gene delivery to endogenous mesenchymal progenitor cells can effectively improve ligament reconstruction in large animals, thereby addressing a major unmet orthopedic need and offering new possibilities for translation to the clinical setting.

3D-Printed Patient-Specific ACL Femoral Tunnel Guide from MRI

Background

Traditional ACL reconstruction with non-anatomic techniques can demonstrate unsatisfactory long-term outcomes with regards instability and the degenerative knee changes observed with these results. Anatomic ACL reconstruction attempts to closely reproduce the patient's individual anatomic characteristics with the aim of restoring knee kinematics, in order to improve patient short and long-term outcomes. We designed an arthroscopic, patient-specific, ACL femoral tunnel guide to aid anatomical placement of the ACL graft within the femoral tunnel.

Methods

The guide design was based on MRI scan of the subject's uninjured contralateral knee, identifying the femoral footprint and its anatomical position relative to the borders of the femoral articular cartilage. Image processing software was used to create a 3D computer aided design which was subsequently exported to a 3D-printing service.

Results

Transparent acrylic based photopolymer, PA220 plastic and 316L stainless steel patient-specific ACL femoral tunnel guides were created; the models produced were accurate with no statistical difference in size and positioning of the center of the ACL femoral footprint guide to MRI (p=0.344, p=0.189, p=0.233 respectively). The guides aim to provide accurate marking of the starting point of the femoral tunnel in arthroscopic ACL reconstruction.

Conclusion

This study serves as a proof of concept for the accurate creation of 3D-printed patient-specific guides for the anatomical placement of the femoral tunnel during ACL reconstruction.

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.

Fibrin clot prevents bone tunnel enlargement after ACL reconstruction with allograft

PURPOSE

Bone tunnel enlargement is a feared complication after ACL reconstruction. The aim of this study was to evaluate whether adding a fibrin clot to the allograft for anatomic single-bundle ACL reconstruction would reduce tunnel widening.

METHODS

Fifty patients who underwent anatomic single-bundle ACL reconstruction were included. Twenty-five patients received an allograft alone, and 25 patients received an allograft with fibrin clot. All patients underwent standard plain anteroposterior and lateral radiographs of the operated knee immediately after surgery and at 1-year follow-up. The size of the tunnels was measured at both time points to calculate tunnel widening. Tunnel widening at 1 year was compared between the allograft and the allograft + fibrin clot group.

RESULTS

There was significantly less tunnel widening in the allograft + fibrin clot group for the femoral tunnel width in the middle and distal portion of the tunnel and for the tibial tunnel width in the proximal and distal portions, as compared to the allograft only group.

CONCLUSION

Adding a fibrin clot to the allograft in anatomic single-bundle ACL reconstruction reduces the amount of tunnel widening at 1-year follow-up. Reducing tunnel widening may positively affect outcomes after ACL surgery and may prevent inadequate bone stock during ACL revision procedures.

LEVEL OF EVIDENCE

Case-control study, Level III.

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.

Arthroscopic Anterior Cruciate Ligament Reconstruction Using a Hamstring Graft with Interference Screw Fixation

Background and Aims:

This study assessed the clinical and radiographic results 3 to 8 years after an arthroscopic ACL reconstruction using a hamstring graft with interference screw fxation on femoral and tibial sites.

Material and Methods:

Seventy-six of 100 patients, who underwent an arthroscopic ACL reconstruction, could be re-examined with a mean follow-up of 5 years.

Results:

The mean Tegner activity score was 4 (scale: 0 to 10) before surgery, and 5 at the follow-up. Fifty-four patients (78%) achieved a satisfactory result in the IKDC rating. The mean Lysholm score was 85 (scale: 0 to 100), the score being better in patients without meniscal resection than those with (P = 0.04). The mean side-to-side difference in anterior-posterior knee laxity was 1.8 mm, and 62 patients (90%) had good stability. Sixty-four patients (93%) had normal range of motion of the knee. Twelve patients (46 %) with meniscal resection had osteoarthritic changes, compared with only 8 of those (20 %) without meniscal resection (P = 0.03).

Conclusions:

This medium-term follow-up study showed that good stability and function and normal range of motion of the knee can be achieved in majority of the patients who have undergone an ACL reconstruction with a hamstring graft and interference screw fixation.

The effect of femoral tunnel widening on one-year clinical outcome after anterior cruciate ligament reconstruction using ZipLoop® technology for fixation in the cortical bone of the femur

BACKGROUND

The effect of femoral tunnel widening on clinical outcomes of anterior cruciate ligament (ACL) reconstruction has been rarely investigated. In this study, ACL reconstructions were performed using semitendinosus and gracilis (STG) tendon grafts and single cortical fixation on the femoral side. The aim was to analyze femoral tunnel widening at one year and to evaluate its effect on clinical and laximetric outcomes.

METHODS

A total of 46 patients were enrolled in this prospective continuous single-operator monocenter study. Clinical protocol included pre-operative and one-year evaluation with subjective and objective International Knee Documentation Committee (IKDC) clinical scores. Computed tomography (CT) scan was used for radiographic examination during the follow-up period. The femoral tunnel widening was measured as a three-dimensional (3D) image using OsiriX software. The cross-sectional area of each tunnel was measured at four different locations.

RESULTS

The subjective preoperative IKDC score was 50 and one-year postoperative score was 81.8. The side-to-side difference in knee laxity decreased from 2.94 to 0.74 mm. The objective IKDC score during the final follow-up was rated A in 27 patients and B in 17. CT scan data revealed an average of 49.32% cone-shaped widening of the femoral tunnel. Femoral tunnel widening at the level of the joint (F4) was negatively correlated with the IKDC subjective score at one year.

CONCLUSIONS

This study revealed a significant widening of the femoral tunnel by demonstrating its conical shape at one year post-surgery. A significant correlation could be established between femoral tunnel widening close to the joint and IKDC scores.

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.

MRI analysis of single-, double-, and triple-bundle anterior cruciate ligament grafts

PURPOSE

The purpose of the study was to evaluate the entire course of ACL grafts on coronal oblique MR images, focusing on differences in graft morphology and graft-to-tunnel healing among single-bundle (SB), double-bundle (DB), and triple-bundle (TB) reconstructions.

METHODS

Eighty-three patients underwent anatomical ACL reconstruction using the semitendinosus tendon. SB reconstruction was performed on 20 patients, DB on 29 patients, and TB on 34 patients. The anteromedial-bundle (AMB) and posterolateral-bundle (PLB) images were extracted from coronal oblique images of grafts at 6 months to visualize their entire course. Signal intensity of grafts was measured independently in three regions: (1) intra-femoral tunnel region, (2) intra-articular region, and (3) intra-tibial tunnel region, followed by calculation of the signal-to-noise quotient (SNQ). To evaluate graft-to-tunnel healing, T2-weighted images were examined for the presence of a high signal-intensity lesion between the graft and bone tunnel around the tunnel aperture.

RESULTS

AMB images showed that SB graft was thick throughout the entire course, while DB graft was thinner than SB graft. TB graft showed a fan shape approaching the tibial tunnels. The SNQ in the femoral tunnel of SB graft was significantly lower than in the DB and TB grafts. High signal-intensity lesions were frequently observed around the femoral tunnel aperture in PLB images of DB and TB grafts compared to SB grafts.

CONCLUSION

Gross morphology of TB grafts resembled that of the natural ACL. However, the graft-to-tunnel healing around the femoral tunnel seemed to be insufficient in PLB images of DB and TB compared to SB grafts.

Effect of tibial drill-guide angle on the mechanical environment at bone tunnel aperture after anatomic single-bundle anterior cruciate ligament reconstruction

PURPOSE

The tibial drill-guide angle in anterior cruciate ligament (ACL) reconstruction influences the tunnel placement and graft-tunnel force, and is potentially associated with post-operative tunnel widening. This study aimed to examine the effect of the drill-guide angle on the stress redistribution at the tibial tunnel aperture after anatomic single-bundle ACL reconstruction.

METHODS

A validated finite element model of human knee joint was used. The tibial tunnel with drill-guide angle ranging from 30° to 75° was investigated. The post-operative stress redistribution in tibia under the compressive, valgus, rotational and complex loadings was analysed.

RESULTS

Compressive loading played a leading role on the stress redistribution at intra-articular tibial tunnel aperture. After ACL reconstruction, stress concentration occurred in the anterior and posterior regions of tunnel aperture while stress reduction occurred in the lateral and posteromedial regions under the compressive loading. Stress redistribution was partially alleviated by using the drill-guide angle ranging from 55° to 65°.

CONCLUSIONS

The present study quantified the effect of bone tunnel drill-guide angle on the post-operative stress redistribution. This phenomenon potentially contributed to tunnel widening. A tunnel drill-guide angle ranging from 55° to 65° was proposed based on the biomechanical rationale. It could serve as a helpful surgical guide for ACL reconstruction.

Anterior Cruciate Ligament Reconstruction and Osteoarthritis: Evidence from Long-Term Follow-Up and Potential Solutions

OBJECTIVE

The goals of this study are to address several questions, the answers to which are key to the understanding and eventually to the prevention of this frequent source of morbidity. These questions include the following: (1) What is the natural history of anterior cruciate ligament (ACL) deficiency? (2) How important is the status of the meniscus at the time of reconstruction? (3) Does ACL reconstruction prevent the development of osteoarthritis in the long term? (4) Can we predict which patients will develop osteoarthritis? (5) What can be done?

DESIGN

This study addresses the key questions above through the long-term follow-up of a cohort of patients treated with ACL reconstruction by Professor Henri Dejour in Lyon, France, supplemented with a review of the relevant literature.

RESULTS

The prevalence of osteoarthritis in ACL-deficient knees is about 40% after 15 years and close to 90% after 25 to 35 years. It remains unclear whether reconstruction of the ACL significantly reduces this risk. The status of the meniscus at the time of ACL reconstruction is a strong predictor of the risk of osteoarthritis: Patients who undergo total meniscectomy are at 2- to 10-fold increased risk of developing osteoarthritis relative to those with intact menisci. Patients showing early evidence of arthritis at short- to medium-term follow-up are at high risk for progression over subsequent years. Numerous emerging techniques may provide tools to more effectively prevent and treat osteoarthritis following ACL injury in the future.

CONCLUSION

Osteoarthritis following ACL injury continues to be a major problem requiring further research.

Cationised gelatin and hyaluronic acid coating enhances polyethylene terephthalate artificial ligament graft osseointegration in porcine bone tunnels

PURPOSE

The aim of this study was to investigate whether cationised gelatin and hyaluronic acid (CH) coating could induce polyethylene terephthalate (PET) artificial ligament graft osseointegration in the bone tunnel.

METHODS

Surface modification of PET artificial ligament graft was performed by layer-by-layer (LBL) self-assembly CH coating. Six pigs underwent anterior cruciate ligament (ACL) reconstruction on the right knees, with three pigs receiving the CH-coated PET grafts and the other three pigs non-CH-coated PET grafts as controls. They were sacrificed at three months after surgery and the graft-bone complexes were acquired for computed tomography (CT) scan and histological examination.

RESULTS

CT scans showed a significant difference at the distal femoral site (p = 0.031) or at the distal tibial site (p = 0.0078), but no significant difference in the bone tunnel areas' enlargement at other sites (p > 0.05) between the CH group and the control group. Histologically, application of CH coating induced new bone formation between graft and bone at three months compared with the controls at the distal site. The interface width of the CH group was significantly lower than that of the control group at the distal femoral site (p = 0.0327) and at the distal tibial site (p = 0.0047).

CONCLUSIONS

The study has shown that CH coating on the PET artificial ligament surface has a positive biological effect in the induction of artificial ligament osseointegration within the bone tunnel at the distal site of the bone tunnel.

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.

Clinical outcomes after anterior cruciate ligament reconstruction: a meta-analysis of autograft versus allograft tissue

BACKGROUND

Clinical outcomes of autograft and allograft anterior cruciate ligament (ACL) reconstructions are mixed, with some reports of excellent to good outcomes and other reports of early graft failure or significant donor site morbidity.

OBJECTIVE

To determine if there is a difference in functional outcomes, failure rates, and stability between autograft and allograft ACL reconstructions.

DATA SOURCES

Medline, Cochrane Central Register of Controlled Trials (Evidence Based Medicine Reviews Collection), Cochrane Database of Systematic Reviews, Web of Science, CINAHL, and SPORTDiscus were searched for articles on ACL reconstruction. Abstracts from annual meetings of the American Academy of Orthopaedic Surgeons, American Orthopaedic Society for Sports Medicine, and Arthroscopy Association of North America were searched for relevant studies.

STUDY SELECTION

INCLUSION CRITERIA FOR STUDIES WERE AS FOLLOWS: primary unilateral ACL injuries, mean patient age less than 41 years, and follow-up for at least 24 months postreconstruction. Exclusion criteria for studies included the following: skeletally immature patients, multiligament injuries, and publication dates before 1990.

DATA EXTRACTION

Joint stability measures included Lachman test, pivot-shift test, KT-1000 arthrometer assessment, and frequency of graft failures. Functional outcome measures included Tegner activity scores, Cincinnati knee scores, Lysholm scores, and IKDC (International Knee Documentation Committee) total scores.

RESULTS

More than 5000 studies were identified. After full text review of 576 studies, 56 were included, of which only 1 directly compared autograft and allograft reconstruction. Allograft ACL reconstructions were more lax when assessed by the KT-1000 arthrometer. For all other outcome measures, there was no statistically significant difference between autograft and allograft ACL reconstruction. For all outcome measures, there was strong evidence of statistical heterogeneity between studies. The sample size necessary for a randomized clinical trial to detect a difference between autograft and allograft reconstruction varied, depending on the outcome.

CONCLUSIONS

With the current literature, only KT-1000 arthrometer assessment demonstrated more laxity with allograft reconstruction. A randomized clinical trial directly comparing allograft to autograft ACL reconstruction is warranted, but a multicenter study would be required to obtain an adequate sample size.

Effect of calcium phosphate-hybridized tendon graft in anterior cruciate ligament reconstruction: a randomized controlled trial

BACKGROUND

The authors developed a novel technique to improve tendon-bone healing by hybridizing calcium phosphate (CaP) with a tendon graft using an alternating soaking process.

HYPOTHESIS

Anterior cruciate ligament (ACL) reconstruction using the CaP-hybridized tendon graft would have a better clinical outcome and reduce the percentage of bone tunnel enlargement compared with a conventional method because of the enhanced anchoring between the tendon graft and the bone.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Patients (N = 64) with unilateral ACL rupture underwent arthroscopically assisted single-bundle ACL reconstruction using a 4-strand semitendinosus tendon or 4-strand semitendinosus and gracilis tendons with EndoButton femoral fixation and screw washer tibial fixation. These patients were equally randomized to undergo the CaP (n = 32) or conventional (n = 32) method using a transtibial tunnel approach according to the closed envelope method. In the CaP group, the tendon graft was hybridized with the CaP at both ends of the graft. One surgeon performed all reconstructions without knowing which graft was prepared. Patients' backgrounds regarding age at surgery, gender, period before surgery, and associated meniscal injuries were similar in the 2 groups. All patients followed the same postoperative protocol. At 1 and 2 years after surgery, they were evaluated with the manual knee laxity test, KT-1000 arthrometry, International Knee Documentation Committee (IKDC) examination form, Tegner scale, and Lysholm scale. Also, 1 year postoperatively, bone tunnel enlargement was analyzed using computed tomography, intensity of the tendon graft by magnetic resonance imaging (MRI), and tendon graft appearance by arthroscopic examination. All the examinations were performed blindly.

RESULTS

All patients underwent a minimum 2-year follow-up. KT-1000 arthrometry data indicated statistically significant decreased average anterior tibial translation in the CaP group compared with the conventional method group: 1.0 ± 2.0 mm versus 1.9 ± 1.6 mm (P < .05), respectively, at 1 year; 1.6 ± 2.1 mm versus 2.6 ± 2.4 mm (P < .05), respectively, at 2 years. The Lysholm score was higher in the CaP group than in the conventional method group at 2 years (96.9 ± 4.3 vs 91.7 ± 13.3, P < .05). The CaP-hybridized tendon graft reduced the percentage of bone tunnel enlargement of the anteroposterior diameter at the main joint aperture site 1 year postoperatively (femoral side: 15.5% ± 13.4% vs 22.1% ± 16.4%, P < .05; tibial side: 19.3% ± 17.1% vs 26.1% ± 13.7%, P < .05). The results of the pivot-shift test, IKDC grade, and Tegner score; the intensity of the tendon graft (MRI); and arthroscopic appearance were not significantly different at both follow-up periods in the 2 groups.

CONCLUSION

The CaP-hybridized tendon graft improved anterior knee stability and Lysholm scores at the 2-year follow-up and improved anterior knee stability and reduced the percentage of bone tunnel enlargement in both tunnels at the 1-year follow-up compared with the conventional method for single-bundle ACL reconstruction. However, longer follow-up is needed to investigate the appearance of any increased instability.

Graft size and patient age are predictors of early revision after anterior cruciate ligament reconstruction with hamstring autograft

PURPOSE

To evaluate whether decreased hamstring autograft size and decreased patient age are predictors of early graft revision.

METHODS

Of 338 consecutive patients undergoing primary anterior cruciate ligament (ACL) reconstruction with hamstring autograft, 256 (75.7%) were evaluated. Graft size and patient age, gender, and body mass index at the time of ACL reconstruction were recorded, along with whether subsequent ACL revision was performed.

RESULTS

The 256 patients comprised 136 male and 120 female patients and ranged in age from 11 to 52 years (mean, 25.0 years). The mean follow-up was 14 months (range, 6 to 47 months). Revision ACL reconstruction was performed in 18 of 256 patients (7.0%) at a mean of 12 months after surgery (range, 3 to 31 months). Revision was performed in 1 of 58 patients (1.7%) with grafts greater than 8 mm in diameter, 9 of 139 patients (6.5%) with 7.5- or 8-mm-diameter grafts, and 8 of 59 patients (13.6%) with grafts 7 mm or less in diameter (P = .027). There was 1 revision performed in the 137 patients aged 20 years or older (0.7%), but 17 revisions were performed in the 119 patients aged under 20 years (14.3%) (P < .0001). Most revisions (16 of 18) were noted to occur in patients aged under 20 years with grafts 8 mm in diameter or less, and the revision rate in this population was 16.4% (16 of 97 patients). Age less than 20 years at reconstruction (odds ratio [OR], 18.97; 95% confidence interval [CI], 2.43 to 147.06; P = .005), decreased graft size (OR, 2.20; 95% CI, 1.00 to 4.85; P = .05), and increased follow-up time (OR, 1.07; 95% CI, 1.02 to 1.12) were associated with increased risk of revision.

CONCLUSIONS

Decreased hamstring autograft size and decreased patient age are predictors of early graft revision. Use of hamstring autografts 8 mm in diameter or less in patients aged under 20 years is associated with higher revision rates.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

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.

Triple-bundle ACL grafts evaluated by second-look arthroscopy

PURPOSE

The purpose of this study was to evaluate the morphology of transplanted triple-bundle anterior cruciate ligament (ACL) grafts by second-look arthroscopy.

METHODS

The subjects were 41 patients with a mean age of 25.5 ± 8.5 years who underwent second-look arthroscopy at between 6 and 22 months after the anatomical triple-bundle ACL reconstruction using semitendinosus tendon autograft. Lachman test was negative in 38 knees and mildly positive with a firm endpoint in 3 knees. Arthroscopic evaluation of grafts was performed for the anteromedial graft (AM), the intermediate graft (IM), and the posterolateral graft (PL), focusing on tension and graft damage.

RESULTS

All grafts showed "fan-out" shape approaching the tibial attachment, which looked closer to the natural ACL compared to the double-bundle grafts. As to graft tension, 93% of AM, 90% of IM, and 88% of PL grafts were evaluated as taut, respectively. As to graft damage, there was no apparent rupture in the AM and IM grafts, while complete or substantial rupture was observed in 10% of PL grafts around the femoral tunnel aperture. The incidence of graft rupture in PL grafts was significantly greater than those in the AM and IM grafts. As to synovial coverage, 76% of AM, 78% of IM, and 59% of PL grafts were evaluated as "Good," while 41% of PL grafts were not fully covered with synovium. All of the synovial defects were observed around the femoral tunnel aperture.

CONCLUSION

The morphology of the triple-bundle grafts resembled that of the natural ACL, while complete or substantial rupture was observed in 10% of the PL grafts.

LEVEL OF EVIDENCE

Study of case series with no comparison group, Level IV.

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.

A medium to long-term follow-up of ACL reconstruction using double gracilis and semitendinosus grafts

This paper reports the results of our approach to ACL tears and knee laxity, based on 30 years of experience in ACL reconstruction with hamstrings and founded on the following cornerstones: the use of doubled semitendinosus and gracilis as a free graft; the use of an out-in technique for femoral drilling and of very strong and stiff fixation devices; the careful examination and repair or reconstruction of the lateral compartment in selected patients; and the use of unaggressive rehabilitation. We prospectively evaluated a series of 100 consecutive patients who underwent ACL reconstruction between 2001 and 2002. A clinical and radiological follow-up was performed at a minimum of 6 years. After 6 years, the International Knee Documentation Committee score demonstrated good-to-excellent results (A and B) in 98% of patients. However, arthrometric results using the KT-1000 demonstrated that 6/80 patients (7.5%) had >5 mm manual maximum side-to-side difference. The median Tegner activity score was 5 (range 1-9); the median Lysholm score was 96 (range 81-100); and the median subjective IKDC score was 94 (range 66-100). We reported 6/80 failures as revealed by a 2+ or 3+ pivot-shift test result and/or KT-1000 side-to-side difference of more than 5 mm. The IKDC score revealed excellent results in all women who underwent extra-articular tenodesis. Radiographic evaluation demonstrated early signs of osteoarthritis in 9% of patients.

The effect of patient and injury factors on long-term outcome after anterior cruciate ligament reconstruction

BACKGROUND

Long-term follow-up is required for accurate assessment of results after anterior cruciate ligament (ACL) reconstruction and recent years have witnessed the publication of numerous papers detailing long-term outcomes. The primary aim of this systematic review was to determine which patient factors affect long-term clinical and radiographic outcomes based on the current literature.

METHODS

A comprehensive literature review yielded 18 prospective manuscripts with minimum follow-up ranging from 5-12 years after ACL reconstruction.

RESULTS

Longer follow-up was associated with increased radiographic evidence of osteoarthritis. Increased meniscal or articular cartilage pathology at ACL reconstruction were found to be associated with increased prevalence of radiographic evidence of osteoarthritis at long-term follow-up in most studies. There is currently insufficient evidence to correlate these intra-articular findings with decreases in clinical outcome measures. Further research is needed to determine the effect of body mass index (BMI) on long-term outcome after ACL reconstruction.

CONCLUSIONS

Intra-articular injuries noted at the time of ACL reconstruction affect long-term results. The effect of BMI and other patient factors is unclear. Long-term follow-up of large multicenter cohorts will provide definitive data on the relative importance of different factors in determining results of ACL reconstruction.

Differentiation between intraoperative and postoperative bone tunnel widening and communication in double-bundle anterior cruciate ligament reconstruction: a prospective study

PURPOSE

The purpose of this study was to determine the amount of intraoperative and postoperative bone tunnel enlargement and communication in double-bundle (DB) anterior cruciate ligament (ACL) reconstruction.

METHODS

Twenty-four consecutive patients undergoing anatomic anteromedial (AM) and posterolateral (PL) 4-tunnel DB ACL reconstruction with a 5-strand hamstring graft and extracortical fixation were included in a prospective case series. Magnetic resonance imaging scans were performed on the second postoperative day and at 7 months' follow up to assess intraoperative and postoperative bone tunnel enlargement and communication. Tunnel widening was determined in different planes by digitally measuring the diameters of the AM and PL bone tunnels.

RESULTS

Intraoperative communication of the AM bone tunnel with the PL bone tunnel caused by drilling was observed in 23.8% of patients on the tibia and in no case on the femur. At 7 months postoperatively, significant bone tunnel widening occurred at all 4 bone tunnels. It was a mean of 20% for the tibial AM bone tunnel, 38% for the tibial PL bone tunnel, 34% for the femoral AM bone tunnel, and 46% for the femoral PL bone tunnel. Postoperative communication of the AM and PL bone tunnels caused by postoperative bone tunnel widening was observed in 19% of patients on the tibia and femur.

CONCLUSIONS

Intraoperative bone tunnel communication in anatomic DB ACL reconstruction was caused by drilling and occurred only on the tibia. Significant postoperative bone tunnel widening occurred at all 4 bone tunnels and was the highest for the PL bone tunnel. Postoperative bone tunnel communication developed in 19% of patients on the tibia and femur and was caused by bone tunnel widening.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

A long-term, prospective, randomized study comparing biodegradable and metal interference screws in anterior cruciate ligament reconstruction surgery: radiographic results and clinical outcome

BACKGROUND

During the past decade, the use of biodegradable implants in anterior cruciate ligament surgery has increased.

HYPOTHESIS

Poly-L-lactide acid (PLLA) interference screws would render the same clinical results but greater tunnel enlargement than metal screws 8 years after anterior cruciate ligament reconstruction using hamstring tendon (semitendinosus/gracilis) autografts.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A randomized series of 77 patients, all with a unilateral anterior cruciate ligament rupture, were divided into 2 groups (PLLA and metal). In both groups, hamstring tendon autografts were used with interference screw fixation at both ends and the patients were examined with standard radiographs, Tegner activity level, Lysholm knee score, single-legged hop test, early C-reactive protein response, and KT-1000 arthrometer knee laxity measurements.

RESULTS

The preoperative assessments in both groups were similar in terms of gender, clinical tests, and the time from injury to surgery. The patients returned for a radiographic and clinical examination a mean of 96 months (range, 78-120 months) after the index operation. The PLLA group displayed significantly larger bone tunnels on the radiographs than the metal group on the femoral side (mean, 11.4 mm [range, 0-17.8 mm] vs 8.0 mm [range, 0-16.3 mm]; P < .005) but not on the tibial side (mean, 10.7 mm [range, 7.8-14.1 mm] vs 10.5 mm [range, 0-20.3 mm]; difference not significant). At follow-up, no significant differences were found between the PLLA and metal groups in terms of knee laxity measurements (median, 1.0 mm [range, -2.0-4.0 mm] vs 1.0 mm [range, -3.0-6.5 mm]), Tegner activity level (median, 7 [range,3-9] vs 6 [range, 2-9]), or the Lysholm knee score (median, 90 points [range, 51-100] vs 89 points [range, 53-100]). The C-reactive protein values did not differ significantly between the 2 groups except for an increase in the PLLA group compared with the metal group at day 1 postoperatively-23 mg/L (range, <6-55) vs 9 mg/L (range, <6-55) (P < .001).

CONCLUSION

There were significantly larger radiographically visible bone tunnels on the femoral side but not on the tibial side in the PLLA group compared with the metal group 8 years after anterior cruciate ligament reconstruction using hamstring tendon autografts. This finding did not correlate with inferior clinical results. Because of the results in the present study, the authors have discontinued the use of PLLA interference screws.

Retear of anterior cruciate ligament grafts in female basketball players: a case series

Background

Incidence of anterior cruciate ligament (ACL) injuries in young female basketball players is higher than that in male basketball players. Graft retears are more frequent with the increasing number of ACL reconstructions. The present study aimed to examine the incidence of retears in competitive female basketball players.

Methods

Sixty-four female basketball players (aged 12 to 29 years) who underwent primary anatomic double-bundle ACL reconstruction using hamstring grafts participated in the study. We investigated incidence, mechanism, and patient characteristics of ACL graft retears. Mann-Whitney U test was used for statistical analysis, and the level of significance was determined at P < 0.05.

Results

Six patients suffered from ACL graft retear (9.4%). Mean duration between primary ACL reconstruction and incidence of retears was 11.7 months. However, there were no other postoperative graft ruptures after 24 months. Primary injury and retear mechanisms varied by patient. At six months after the primary ACL reconstruction surgery, mean quadriceps and hamstring strengths were 81% and 87%, respectively, indicating favorable recovery of muscle strength. However, preoperative quadriceps and hamstring strength in the retear group were 65% and 71%, respectively. In particular, preoperative quadriceps strength in the retear group demonstrated a lower value than that in the uninjured group (P < 0.05).

Conclusions

We observed a high incidence of ACL graft retears in competitive female basketball players, as previously reported. Considering the timing of graft retear occurrences, an early return to playing basketball should be avoided following ACL reconstruction. Closer attention should be paid to player preoperative condition, as well as muscle strength and postoperative status.

Rehabilitation results following anterior cruciate ligament reconstruction using a hard brace compared to a fluid-filled soft brace

The purpose of this study was to compare the clinical outcomes of rehabilitation after ACL reconstruction using a water-filled soft brace to those using a hard brace. The method used in this study was a prospective randomised clinical trial including 36 patients wearing a hard brace and 37 patients wearing a water-filled soft brace for 6 weeks after surgery. Preoperative and postoperative (seven examinations) clinical evaluation within a follow-up period of 1 year including effusion status, swelling and range of motion (ROM), IKDC 2000, KT1000 Arthrometer, Lysholm knee scoring scale and Tegner activity score. Mean values are presented with standard deviations. Data was analysed using descriptive statistics and Student's t-test for unpaired samples. Significantly less effusion was found in the soft brace group from 5 days (p=0.002) to 12 weeks (p<0.024) postoperative. Hard brace patients presented with significantly more extension deficit from 5 days (p=0.036) to 12 months (p=0.014) postoperative but no significant difference was detected in complete ROM, laxity or thigh atrophy at any follow-up examination. Patients treated with a soft brace had significantly higher IKDC subjective ratings at 6 weeks (p=0.02) up to 12 months after operation (p=0.002) and rated significantly higher in Tegner activity score (p=0.004) and Lysholm knee scoring scale (p=0.006) 6 and 12 months (p<0.001 for both scores) postoperatively. The water-filled soft brace was superior regarding effusion, swelling, extension deficit and patient-measured midterm outcome. The soft brace presents a safe, easy-to-use and effective alternative to the hard brace.

Comparison between single-and double-bundle anterior cruciate ligament reconstruction: a prospective, randomized, single-blinded clinical trial

BACKGROUND

Double-bundle ACL reconstruction popularity is increasing with the aim to reproduce native ACL anatomy and improve ACL reconstruction outcome. However, to date, only a few randomized clinical studies have been published.

PURPOSE

The aim of this study was to prospectively compare the clinical results of single- and double-bundle ACL reconstruction.

STUDY DESIGN

Randomized controlled clinical trial; Level of evidence, 1.

METHODS

Seventy patients with a chronic unilateral ACL rupture who underwent arthroscopically assisted ACL reconstruction using a hamstring graft were randomized to receive a single- (SB) or double-bundle (DB) reconstruction. Both groups were comparable with regard to preoperative data. A double-incision surgical technique was adopted in both groups. The graft was fixed by looping the hamstring tendons around a bony (DB) or a metallic (SB) bridge on the tibial side and with interference screws reinforced with a staple on the femur. The same rehabilitation protocol was adopted. Outcome assessment was performed by a blinded, independent observer using the visual analog scale (VAS) score, the new International Knee Documentation Committee (IKDC) form, the Knee Injury and Osteoarthritis Outcome Score (KOOS), and KT-1000 arthrometer evaluation.

RESULTS

All the patients reached a minimum follow-up of 2 years. No differences between the 2 groups were observed in terms of KOOS and IKDC subjective score. A statistically significant difference in favor of the DB group was found with the VAS (P < .03). The objective IKDC final scores showed statistically significantly more "normal knees" in the DB group than in the SB group (P = .03). There was 1 stability failure in the DB group and 3 in the SB group. The KT-1000 arthrometer data showed a statistically significant decrease in the average anterior tibial translation in the DB group (1.2 mm DB vs 2.1 mm SB; P < .03). The incidence of a residual pivot-shift glide was 14% in DB and 26% in SB (P = .08).

CONCLUSION

In the 2-year minimum follow-up, DB ACL reconstructions showed better VAS, anterior knee laxity, and final objective IKDC scores than SB. However, longer follow-up and accurate instrumented in vivo rotational stability assessment are needed.

Anterior cruciate ligament reconstruction: assessment of the hamstring autograft femoral fixation using the EndoButton CL

The objective of this study was to evaluate the clinical and radiological results of a prospective, continuous series of 105 ACL reconstructions using the STG tendons fixed to the femur by an EndoButton CL, with more than 4 years of follow-up.

HYPOTHESIS

The subjective and objective clinical results as well as the radiological results (tunnel enlargement) obtained by a cortical, extra-anatomic femoral fixation are at least equivalent to the results obtained with other types of femoral fixation systems.

MATERIAL AND METHODS

One hundred and five patients aged with a mean 26 years (range, 12-56 years) were operated on for an anterior cruciate ligament rupture using the same technique and by the same operator: four-strand STG fixed to the tibia by a double fixation--BioRCI-HA screw and staple--and on the femur by an EndoButton CL (Smith and Nephew). The results were assessed at 6 months, 1 and 2 years and then at a mean follow-up of 51 months, both clinically (IKDC, Lysholm, KT-1000) and radiologically (Telos laximetry, tunnel position, and morphological analysis).

RESULTS

No complications related to the use of the EndoButton were observed. No additional interference screw was necessary. According to the IKDC laxity classification, 91.4% of the patients were classified in category A or B, nine knees (8.6%) were classified C or D. Four failures required revision with a patellar tendon graft. On the final IKDC score, 63 patients (60%) were classified grade A, 37 grade B (35.3%), four grade C (3.8%), and one grade D (0.9%). On the Telos laximetry, 62 patients (59%) had a differential laxity less than or equal to 2 mm. The mean value was 1.8 mm (range, 0-11). Tibial tunnel enlargement was constant; femoral tunnel enlargement was significant (>2 mm) in 27.6% of the knees. No femoral tunnel diameter modification corresponding to the EndoButton passage was observed.

DISCUSSION

The results of this series are comparable to the results of other series. Its reproducibility and the absence of iatrogenic complications for this femoral EndoButton CL fixation make it a top-choice technique, like the corticocancellous graft procedures, but without their disadvantages. No secondary elongation attributable to the EndoButton CL was observed. This femoral fixation procedure appeared necessary and sufficient to providing good mechanical stability for the graft in the femoral tunnel.

The 1:1 versus the 2:2 tunnel-drilling technique: optimization of fixation strength and stiffness in an all-inside double-bundle anterior cruciate ligament reconstruction--a biomechanical study

BACKGROUND

Double-bundle anterior cruciate ligament (ACL) reconstructions involve drilling 2 tibial tunnels separated by a narrow 2-mm bone bridge. The sequence of reaming and drilling the tibial tunnels for double-bundle ACL reconstructions has not been defined.

HYPOTHESIS

Fixing a graft in the posterolateral ACL tibial tunnel before reaming the anteromedial tibial tunnel will reduce the number of complications, as compared with drilling both the anteromedial and posterolateral tunnels before graft fixation, when performing double-bundle ACL reconstructions.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve porcine tibias were divided into 2 groups of 6 specimens. Fresh bovine extensor tendons grafts were fixed in 7-mm tunnels reamed using an inside-out method. Grafts were fixed in a retrograde fashion with 7-mm bioabsorbable retrograde screws. The tibias in group 1 were reconstructed by reaming and reconstructing the posterolateral tunnel before reaming and securing the graft for the anteromedial tunnel (ie, 1:1 method), whereas those in the second group were reconstructed by reaming both tunnels before graft fixation in either (ie, the 2:2 method). The specimens were biomechanically tested with cyclic and load-to-failure parameters.

RESULTS

Cyclic testing revealed no significant difference between the 2 methods in displacement or stiffness. In load-to-failure testing, the 1:1 group withstood significantly higher initial failure loads and ultimate loads. Pullout displacement was significantly higher for the 1:1 group. Whereas no tibias in the 1:1 group sustained fractures, 4 from the 2:2 group demonstrated a bone bridge fracture.

CONCLUSION

Soft tissue ACL grafts fixed in the tibia with the 1:1 method withstood significantly higher initial and ultimate failure loads and were stiffer than the grafts fixed with the 2:2 method. Tibias fixed with the 1:1 method were also less susceptible to bone bridge fracture.

CLINICAL RELEVANCE

The potential for a lower complication rate and greater pullout strength seen with the 1:1 method may prove useful to surgeons performing anatomic double-bundle ACL reconstructions, in addition to other procedures involving reconstructing 2 closely positioned tunnels, including anatomic posterolateral corner and medial collateral reconstructions.

Knee osteoarthritis after anterior cruciate ligament injury: a systematic review

BACKGROUND

This is a systematic review of studies on the prevalence of osteoarthritis in the tibiofemoral joint more than 10 years after an anterior cruciate ligament injury, the radiologic classification methods used, and risk factors for development of knee osteoarthritis.

METHODS

A systematic search was performed in PubMed, EMBASE, and AMED. Inclusion criteria were studies involving patients with anterior cruciate ligament injury, either isolated or combined with medial collateral ligament or meniscal injury and either surgically or nonsurgically treated, and a minimum 10-year follow-up with radiologic assessment. Methodological quality was evaluated using a modified version of the Coleman methodology score.

RESULTS

Seven prospective and 24 retrospective studies were included. The mean modified Coleman methodology score was 52 of 90. Reported prevalence of knee osteoarthritis for subjects with isolated anterior cruciate ligament injury was between 0% and 13%. For subjects with anterior cruciate ligament and additional meniscal injury, the prevalence varied between 21% and 48%. Seven different radiologic classification systems were used in the studies. Only 3 studies reported reliability results for the radiologic assessments. The most frequently reported risk factor for development of knee osteoarthritis was meniscal injury.

CONCLUSION

This systematic review suggests that the prevalence rates of knee osteoarthritis after anterior cruciate ligament reconstruction reported by previous reviews have been too high. The highest rated studies reported low prevalence of knee osteoarthritis for individuals with isolated anterior cruciate ligament injury (0%-13%) and a higher prevalence of knee osteoarthritis for subjects with combined injuries (21%-48%). Overall, the modified Coleman methodology score was low for the included studies. No universal methodological radiologic classification method exists, making comparisons of the studies and stating firm conclusions on the prevalence of knee osteoarthritis more than 10 years after anterior cruciate ligament injury difficult.

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

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

Tunnel enlargement after double-bundle anterior cruciate ligament reconstruction: a prospective, randomized study

PURPOSE

The aim of this study was to compare tunnel enlargement in patients with double-bundle and single-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

Sixty patients were randomized by closed envelopes into 2 different groups of ACL reconstruction with hamstring tendons: double-bundle technique with bioabsorbable screw fixation (n = 35) and single-bundle technique with bioabsorbable screw fixation (n = 25). Magnetic resonance imaging evaluation was performed in 53 patients (88%) (32 in double-bundle group and 21 in single-bundle group) for a mean of 27 months' follow-up (range, 24 to 36 months). Tunnel enlargement was determined by digital measurement of the widths perpendicular to the long axis of the tunnels on an oblique coronal and sagittal plane. The magnetic resonance imaging measurements were compared with the intraoperative drill diameter.

RESULTS

No significant differences were found between the double-bundle group and the single-bundle group in tunnel enlargement on the femoral side. However, on the tibial side, tunnel enlargement was greater in the single-bundle group than in the double-bundle group in each tunnel (P = .051). In all knees, tunnel enlargement both on the tibial side and on the femoral side correlated significantly with the anterior and rotational laxity of the operated knee. In the double-bundle group, no tunnel communication between the anteromedial and posterolateral tunnels was seen in any of the patients on either the tibial side or femoral side.

CONCLUSIONS

This prospective, randomized study showed that our double-bundle ACL reconstruction technique results in less tunnel enlargement in each tunnel on the tibial side than the single-bundle technique with similar fixation methods, graft material, and rehabilitation. In addition, no tunnel communication was observed in the patients undergoing double-bundle ACL reconstruction. The clinical results were good in both groups. However, the patients who had more tunnel enlargement had significantly more anterior and rotational laxity of the operated knee as well.

LEVEL OF EVIDENCE

Level I, therapeutic randomized controlled trial.

Effect of compaction drilling during ACL reconstruction with hamstrings on postoperative tunnel widening

TYPE OF STUDY

This study investigates whether the amount of tibial and femoral bone tunnel enlargement following anterior cruciate ligament (ACL) reconstruction with hamstrings can be reduced by compaction bone tunnel drilling.

METHODS

Patients undergoing primary ACL reconstruction with four-strand hamstrings (n = 26) were matched to either extraction drilling (n = 13) or compaction drilling (n = 13). Extracortical femoral fixation was by means of a 20 mm Endobutton CL and tibial fixation was by resorbable interference screw. A CT scan was performed on the second postoperative day and an average of 4 months (range 3.8-5 months) postoperatively in all patients. Tunnel enlargement was determined by digitally measuring the widths perpendicular to the long axis of the tunnels on an oblique coronal and axial plane. The CT measurements were compared to the intraoperative drill diameter.

RESULTS

With extraction drilling the average tibial tunnel diameter proximal to the interference screw increased from 8.5 to 10.4 mm (P < 0.0001) and the average femoral tunnel from 8.0 to 10.6 mm (P < 0.0001). With compaction drilling it increased from 8.2 to 10.0 mm (P < 0.0001) and from 7.6 to 9.7 mm (P < 0.002), respectively. Tunnel widening was 22% on the tibial side for both groups and 33 versus 28% on the femoral side (P = 0.09) for extraction versus compaction drilling.

CONCLUSION

There was a significant tibial and femoral tunnel widening on CT an average of only 4 months following ACL reconstruction with hamstrings. Compaction drilling with a stepped router did not prove to reduce the postoperative tunnel widening significantly. Tunnel widening was higher on the femoral side which could be related to the extracortical femoral fixation technique.

LEVEL OF EVIDENCE

Level 4.

Biomechanical comparison between CentraLoc and Intrafix fixation of quadrupled semitendinosus-gracilis allografts in cadaveric tibiae with low bone mineral density

Supplementary or back-up tibial tunnel fixation of a quadruple semitendinosus-gracilis (STG) graft is often performed when the knee surgeon questions the integrity of intra-tunnel fixation. Back-up fixation devices such as staples however may contribute to increased knee pain and dysfunction. Both primary extra-tunnel and intra-tunnel fixation devices may provide sufficient quadruple STG graft fixation in a tibial tunnel to preclude the need for back-up fixation. This biomechanical study compared the fixation of quadruple STG allografts in standard drilled tunnels prepared in low apparent bone mineral density (BMD) cadaveric tibiae using either an Intrafix device with primary intra-tunnel fixation in a region of predominantly cancellous trabecular bone, or a CentraLoc device with primary extra-tunnel fixation in a region of predominantly cortical bone. The study hypothesis was that the CentraLoc device would display superior fixation in these low apparent BMD cadaveric tibiae. Matched pair tibiae and quadruple STG allografts were divided into two groups of seven specimens each. Extraction drilled tunnels matched allograft diameter. Constructs were pretensioned on a servo hydraulic device between 10 and 50 N for 10 cycles and isometric pretensioned at 50 N for 1 min prior to undergoing 500 loading cycles (50-250 N) and load to failure testing (20 mm/min). The CentraLoc group displayed superior load at failure (448.4+/-171 N vs. 338.4+/-119 N, P=0.04) and survived more loading cycles (410+/-154 cycles vs. 196+/-230 cycles, P=0.04) than the Intrafix group. Most CentraLoc group specimens (6/7, 85.7%) failed by device pullout with intact quadruple STG allograft strands while all Intrafix group specimens (7/7, 100%) failed by slippage of one or more strands (P=0.005).

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

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

Anterior cruciate ligament reconstruction with quadrupled semitendinosus tendon - minimum 6 year clinical and radiological follow-up

This clinical study evaluates the minimum 6 year follow-up clinical, functional, radiological and isometric results after arthroscopic reconstruction of the anterior cruciate ligament (ACL) with quadrupled semitendinosus tendon autograft (femoral endobutton and tibial suture disc fixation). Seventy out of 85 operated patients (lost to follow-up 17%) with an average age of 34.3 years could be clinically examined at a mean follow-up time of 6 years and 4 months after surgery. Results revealed a high subjective satisfaction rate of 93%. The preoperative activity level could be maintained in 71% of the patients. The Lysholm score showed very good and good results in 85% with a mean of 83.6%. Normal or nearly normal results on the IKDC score were reported in 85% of the patients. The KT-1000 arthrometer stability testing showed a difference of less than 3 mm compared to the contralateral knee in 75% of the patients. Five patients (7%) had a graft failure during follow-up time. There were no or only mild degenerative changes at the radiographic evaluation in 85% of the patients. In 15% of the patients a femoral and in 40% a tibial tunnel widening of more than 50% was observed, however without a relevance for the clinical and functional status. Midterm results obtained in this study after arthroscopic ACL reconstruction with the quadrupled semitendinosus tendon confirm the outcomes in the literature after shorter follow-up periods that provide very good and good subjective, functional and stability results in about 80-85% of the patients. This surgical technique can be recommended for the active patient with ACL deficiency. However, patients must be informed that activity level cannot always be maintained and a failure rate of 5-10% must be taken into account in the longer term when decision for surgery is made.

Arthroscopic evaluation of ACL grafts reconstructed with the anatomical two-bundle technique using hamstring tendon autograft

This article describes second-look arthroscopic evaluation of the transplanted grafts after anatomical two-bundle ACL reconstruction, which had been performed between December 2000 and March 2004. Using two double-looped semitendinosus tendon grafts via separate femoral and tibial tunnels in the anatomical ACL footprints, 65 patients (mean age of 24 years) underwent anatomical two-bundle ACL reconstruction. The evaluation was performed for those who had undergone the procedure 5-29 months (mean 16.5) previously, with emphasis on graft tension and the presence of graft damage by meticulous probing. None of the anteromedial (AM) grafts showed rupture, while 11% of the posterolateral (PL) grafts showed substantial damage around the femoral tunnel aperture. Both the AM and PL grafts were evaluated as lax without apparent graft rupture in 9% of the knees. These results suggest that the currently performed anatomical two-bundle ACL reconstruction and postoperative regimen still remain to be improved to achieve better postoperative graft morphology.

Observations on bone tunnel enlargement after double-bundle anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to determine the amount of tibial and femoral bone tunnel enlargement after double-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

Twenty-five consecutive patients undergoing primary double-bundle hamstring ACL reconstruction were included in a prospective case series. Femoral fixation was performed by means of 2 EndoButton CL devices (Smith & Nephew Endoscopy, Andover, MA), and tibial fixation was done with 2 bioresorbable interference screws. Magnetic resonance imaging (MRI) was performed in all patients at a mean of 12.3 months postoperatively. Tunnel enlargement was determined by digitally measuring the widths perpendicular to the long axis of the anteromedial (AM) and posterolateral (PL) tunnels on an oblique coronal and axial plane. The MRI measurements were compared with the intraoperative drill diameter.

RESULTS

The mean tibial AM bone tunnel diameter increased from 0.74 to 1.06 cm, and the mean PL diameter increased from 0.60 to 0.89 cm. The mean femoral AM bone tunnel diameter increased from 0.71 to 0.97 cm, and the mean PL diameter increased from 0.58 to 0.85 cm. Bone tunnel enlargement was 43% (P = .001) for both tibial tunnels and 35% (P = .001) versus 48% (P < .001) for the femoral AM bone tunnel versus the PL femoral bone tunnel. On the tibial side, communication of the bone tunnels occurred in 41% of patients.

CONCLUSIONS

This study shows significant tibial and femoral bone tunnel enlargement on MRI after 4-tunnel double-bundle ACL reconstruction 1 year postoperatively. In 41% of patients separate tibial bone tunnel measurements were impossible because of tunnel communication caused by intraoperative bone tunnel drilling, screw contact, or postoperative bone tunnel enlargement. On the femoral side, no bone tunnel communication occurred. The short-term clinical results were good and were not influenced by tunnel communication.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

KT-1000 records smaller side-to-side differences than radiostereometric analysis before and after an ACL reconstruction

The KT-1000 and similar non-invasive arthrometers are used as a complement to clinical examination in the diagnosis of anterior cruciate ligament (ACL) rupture and during the follow-up after surgery. We compared the two methods, KT-1000 and Radiostereometric analysis (RSA), when used to measure anterior-posterior knee laxity (A-P laxity) in patients with ACL rupture, before and after the reconstruction of this ligament, in a prospective, comparative study. Twenty-two consecutive patients (14 men, 8 women) with a median age of 24 years (range 16-41) were studied. All the patients had a unilateral ACL rupture and an intact contralateral knee. The patients were operated on by one experienced surgeon using the bone-patellar tendon-bone (BTB) autograft. Preoperatively and 2 years after the reconstruction, all the patients were evaluated using KT-1000 and RSA measurements of A-P laxity. The side-to-side differences between the injured and the intact knees, that is, total A-P laxity for both knees, are presented. Preoperatively, the median side-to-side differences using the two methods (KT-1000/RSA) were 4.0 (0-10)/7.4 mm (2.2-17.4) (P<0.0001). The total A-P laxity on the injured side was 11.0 (6.0-18.0)/10.9 mm (6.2-19.6) (n.s), while it was 8.0 (6.0-10.0)/3.1 mm (0.2-8.6) on the intact side (P<0.0001). A side-to-side difference of more than 3.0 mm was defined as the cut-off value for indicating ACL rupture. Using the KT-1000, 11 of 22 (50%) patients had a cut-off value above 3.0 mm, while the corresponding figure for RSA was 21/22 (95%) patients. At the 2-year follow-up, the median side-to-side differences using the two methods (KT-1000/RSA) were 0.5 (-1.5 to 4.0)/2.8 mm (-1.8 to 10.7) (P<0.0001). The total A-P laxity on the operated side was 9.5 (7.5-14.0)/6.5 mm (2.4-14.1) (P<0.0001). We conclude that the KT-1000 recorded significantly smaller side-to-side differences than did the RSA, both before and after the reconstruction of the ACL using a BTB autograft. Before it was mainly an effect of larger A-P laxity recordings with KT-1000 on the intact side, and after the reconstruction, the KT-1000 still recorded larger A-P laxity on the intact side and also larger A-P laxity on the reconstructed side than RSA.

Early healing of flexor tendon insertion site injuries: Tunnel repair is mechanically and histologically inferior to surface repair in a canine model

Orthopedic injuries often require surgical reattachment of tendon to bone. Tendon ends can be sutured to bone by direct apposition to the bone surface or by placement within a bone tunnel. Our objective was to compare early healing of a traditional surface versus a novel tunnel method for repair of the flexor digitorum profundus (FDP) tendon insertion site in a canine model. A total of 70 tendon-bone specimens were analyzed 0, 5, 10 or 21 days after injury and repair, using tensile and range of motion mechanical testing, histology and densitometry. Ultimate force (a measure of repair strength) did not differ between surface and tunnel repairs at day 0. Both repair types had reduced strength at 10 and 21 days compared to 0 days, indicative of deterioration of suture grasping strength (tendon softening). At 21 days, tendons repaired in a bone tunnel had 38% lower ultimate force compared to surface repairs (p = 0.017). Histological findings were comparable between repair groups at 5 and 10 days but differed at 21 days, when we saw evidence of maturation of the tendon-bone interface in the surface repairs compared to an immature fibrous interface with no evidence of tendon-bone integration in the tunnel repairs. After accounting for bone removed by the tunnel, no difference in bone mineral density or trabecular bone volume existed between surface and tunnel repairs. If the results of our animal study extend to healing of the human FDP insertion, they indicate that FDP tendons should be reattached to the distal phalanx by suture to the cortical surface rather than suture in a bone tunnel.