Variability in ACL tunnel placement: observational clinical study of surgeon ACL tunnel variability

Anatomic Factors Associated With the Development of an Anterior Cruciate Ligament Rerupture in Men: A Case-Control Study

BACKGROUND

Although several factors are associated with anterior cruciate ligament (ACL) rerupture, the effect of anatomic factors associated with ACL rupture on ACL rerupture development has not been evaluated.

PURPOSE

To determine individual anatomic parameters independently associated with ACL rerupture and the diagnostic values of these parameters.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A total of 91 male patients with ACL rerupture and 182 age-, sex-, body mass index-, and side dominance-matched patients without rerupture who underwent ACL reconstruction with a 5-year follow-up were included. In all, 35 parameters that were previously defined as risk factors for primary ACL rupture were compared between the 2 groups. Uni- and multivariate logistic regression models were created to evaluate independently associated factors. Receiver operating characteristic curve analysis was performed for independently associated parameters to predict sensitivity, specificity, and cutoff values.

RESULTS

The mean ± standard deviation age of patients at the time of index surgery was 26.5 ± 6.7 years. Notch shape index (P = .014), tibial proximal anteroposterior (AP) distance (TPAPD) (P < .001), lateral femoral condylar AP distance (LCAPD)/TPAPD ratio (P < .001), medial meniscal cartilage bone height (P < .001), and lateral meniscal bone angle (P = .004) were found to be significantly different between the 2 groups. Only the LCAPD/TPAPD ratio (odds ratio, 2.713; 95% CI, 1.998-5.480; P < .001) was found to be independently associated with ACL rerupture development. The LCAPD/TPAPD ratio revealed 78.9% sensitivity and 75.5% specificity (area under the curve, 0.815; 95% CI, 0.760-0.870) for values above 1.52.

CONCLUSION

The LCAPD/TPAPD ratio can be used to distinguish patients who are at risk of developing ACL rerupture from patients who are not. In the clinical practice, findings of this study may help to develop surgical and nonsurgical preventive strategies in ACL rerupture development.

Validation of a Risk Calculator to Personalize Graft Choice and Reduce Rupture Rates for Anterior Cruciate Ligament Reconstruction

BACKGROUND

Anterior cruciate ligament reconstructions (ACLRs) fail at an alarmingly high rate in young active individuals. The Multicenter Orthopaedic Outcomes Network (MOON) knee group has developed an autograft risk calculator that uses patient characteristics and lifestyle to predict the probability of graft rupture if the surgeon uses a hamstring tendon (HT) or a bone-patellar tendon-bone (BPTB) graft to reconstruct the ligament. If validated, this risk calculator can be used during the shared decision-making process to make optimal ACLR autograft choices and reduce rupture rates. The STABILITY 1 randomized clinical trial offers a large, rigorously collected data set of similar young active patients who received HT autograft with or without lateral extra-articular tenodesis (LET) for ACLR.

PURPOSE/HYPOTHESIS

The purpose was to validate the ACLR graft rupture risk calculator in a large external data set and to investigate the utility of BPTB and LET for ACLR. We hypothesized that the risk calculator would maintain adequate discriminative ability and calibration in the external STABILITY 1 data set when compared with the initial MOON development data set.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 1.

METHODS

The model predictors for the risk calculator include age, sex, body mass index, sport played at the time of injury, Marx Activity Score, preoperative knee laxity, and graft type. The STABILITY 1 trial data set was used for external validation. Discriminative ability, calibration, and diagnostic test validity of the model were assessed. Finally, predictor strength in the initial and validation samples was compared.

RESULTS

The model showed acceptable discriminative ability (area under the curve = 0.73), calibration (Brier score = 0.07), and specificity (85.3%) to detect patients who will experience a graft rupture. Age, high-grade preoperative knee laxity, and graft type were significant predictors of graft rupture in young active patients. BPTB and the addition of LET to HT were protective against graft rupture versus HT autograft alone.

CONCLUSION

The MOON risk calculator is a valid predictor of ACLR graft rupture and is appropriate for clinical practice. This study provides evidence supporting the idea that isolated HT autografts should be avoided for young active patients undergoing ACLR.

REGISTRATION

NCT00463099 (MOON); NCT02018354 (STABILITY 1) (ClinicalTrials.gov identifiers).

The Clinical Radiographic Incidence of Posttraumatic Osteoarthritis 10 Years After Anterior Cruciate Ligament Reconstruction: Data From the MOON Nested Cohort

BACKGROUND

The incidence of posttraumatic osteoarthritis (PTOA) based on clinical radiographic grading criteria at 10 years after anterior cruciate ligament (ACL) reconstruction (ACLR) has not been well-defined in a prospective cohort of young athletic patients.

HYPOTHESIS

Among young athletic patients, there is a high incidence of clinical radiographic PTOA at 10 years after ACLR. Additionally, there is a significant difference in clinical radiographic osteoarthritis (OA) changes (joint space narrowing and osteophyte formation) between ACL-reconstructed and contralateral knees at 10 years.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The first 146 patients in an ongoing nested cohort study of the Multicenter Orthopaedic Outcomes Network (MOON) prospective cohort presented for a minimum 10-year follow-up. Included patients had a sports-related ACL injury, were aged <33 years at the time of ACLR, had no history of ipsilateral or contralateral knee surgery, and did not undergo revision ACLR before follow-up. Bilateral knee metatarsophalangeal view radiographs were obtained and graded according to International Knee Documentation Committee (IKDC), Osteoarthritis Research Society International (OARSI), and modified Kellgren-Lawrence (KL) criteria by 2 blinded reviewers. The incidence and severity of ipsilateral and contralateral radiographic OA were determined among patients without a contralateral ACL injury before 10-year follow-up (N = 133).

RESULTS

Interrater reliability was substantial for the IKDC (Gwet Agreement Coefficient [AC] 1 = 0.71), moderate for the KL (0.48), and almost perfect for the OARSI (0.84) grading systems. Among patients with a contralateral radiographically normal knee, the 10-year incidence of clinical radiographic PTOA after ACLR was 37% as defined by osteophytes and 23% as defined by joint space narrowing. The maximum side-to-side difference in the OARSI osteophyte grade in the medial or lateral compartment was 0 in 65% of patients, 1 in 20%, and ≥2 in 15%. The maximum side-to-side difference in the OARSI joint space narrowing grade was 0 in 77% of patients, 1 in 19%, and ≥2 in 4%.

CONCLUSION

In young active patients, the 10-year incidence of clinical radiographic PTOA after ACLR was 37% as defined by osteophytes and 23% as defined by joint space narrowing. The mean difference in the degree of osteophyte formation (≤1 grade in 85%) and joint space narrowing (≤1 grade in 96%) between the ACL-reconstructed and contralateral knees was small.

REGISTRATION

NCT02717559 (ClinicalTrials.gov identifier).

The REVision Using Imaging to Guide Staging and Evaluation (REVISE) in ACL Reconstruction Classification

Revision anterior cruciate ligament (ACL) procedures are increasing in incidence and possess markedly inferior clinical outcomes (76% satisfaction) and return-to-sports (57%) rates than their primary counterparts. Given their complexity, a universal language is required to identify and communicate the technical challenges faced with revision procedures and guide treatment strategies. The proposed REV: ision using I: maging to guide S: taging and E: valuation (REVISE) ACL (anterior cruciate ligament) Classification can serve as a foundation for this universal language that is feasible and practical with acceptable inter-rater agreement. A focus group of sports medicine fellowship-trained orthopaedic surgeons was assembled to develop a classification to assess femoral/tibial tunnel "usability" (placement, widening, overlap) and guide the revision reconstruction strategy (one-stage vs. two-stage) post-failed ACL reconstruction. Twelve board-certified sports medicine orthopaedic surgeons independently applied the classification to the de-identified computed tomographic (CT) scan data of 10 patients, randomly selected, who failed ACL reconstruction. An interclass correlation coefficient (ICC) was calculated (with 95% confidence intervals) to assess agreement among reviewers concerning the three major classifications of the proposed system. Across surgeons, and on an individual patient basis, there was high internal validity and observed agreement on treatment strategy (one-stage vs. two-stage revision). Reliability testing of the classification using CT scan data demonstrated an ICC (95% confidence interval) of 0.92 (0.80-0.98) suggesting "substantial" agreement between the surgeons across all patients for all elements of the classification. The proposed REVISE ACL Classification, which employs CT scan analysis to both identify technical issues and guide revision ACL treatment strategy (one- or two-stage), constitutes a feasible and practical system with high internal validity, high observed agreement, and substantial inter-rater agreement. Adoption of this classification, both clinically and in research, will help provide a universal language for orthopaedic surgeons to discuss these complex clinical presentations and help standardize an approach to diagnosis and treatment to improve patient outcomes. The Level of Evidence for this study is 3.

One-Stage Anatomical Revision Anterior Cruciate Ligament Reconstruction: Results According to Tunnel Overlaps

PURPOSE

To present clinical results according to tunnel overlap in 1-stage anatomical revision anterior cruciate ligament reconstruction (ACLR).

METHODS

All patients who underwent revision ACLR performed by a single surgeon (J.H.A.) from 2012 to 2017 and were followed up for >24 months were retrospectively evaluated. The exclusion criteria were concomitant ligament injury, including medial collateral ligament injury, modified Outerbridge grade ≥3 cartilage lesion, and severe meniscus defects. Tunnel overlap was measured on 3-dimensionally reconstructed computed tomography images. Patients in the nonoverlapped femoral tunnel group (group NO, n = 52) were treated with new tunnel drilling that completely avoided previous tunnels, and those in the overlapped femoral tunnel group (group O, n = 41) were treated with a new tunnel that overlapped with previous tunnels. Clinical outcomes were evaluated using the subjective International Knee Documentation Committee (IKDC) and Lysholm scores. Knee joint stability was measured using the Lachman and pivot shift tests. Patients with femoral tunnel widening of ≥14 mm underwent 2-stage ACLR.

RESULTS

The mean follow-up duration of 93 patients was 46.9 months (range, 24-97 months). All preoperative subjective and objective IKDC (P<0.001) and Telos stress test scores (P = .016) were significantly improved at the last follow-up. Forty-one patients had overlapping femoral tunnels, whereas 87 had overlapping tibial tunnels. At the last follow-up, subjective IKDC and Lysholm scores (73.6 ± 15.3 vs 74.9 ± 12.1, P = .799 and 80.0 ± 19.2 vs 81.44 ± 13.5, P = .505, respectively) and objective pivot shift (IKDC grade) in the Lachman test (P = .183 and P = .450, respectively) did not differ significantly between groups NO and O, respectively.

CONCLUSIONS

One-stage anatomical revision ACLR significantly improved the clinical results. Most tibial tunnels (94%) and approximately one-half (44%) of the femoral tunnels overlapped. The overlapped femoral tunnel group did not show inferior outcomes or stability.

LEVEL OF EVIDENCE

Level III, cohort study.

Intraoperative fluoroscopy shows better agreement and interchangeability in tibial tunnel location during single bundle anterior cruciate ligament reconstruction with postoperative three-dimensional computed tomography compared with an intraoperative image-free navigation system

BACKGROUND

Fluoroscopy and navigation systems provide an accurate and reproducible method of guiding anatomical tunnel positioning during anterior cruciate ligament reconstruction (ACLR). The aim was to evaluate the differences in tibial tunnel location assessed by both an intraoperative navigation system and fluoroscopy, validated using a one-week postoperative three-dimensional computed tomography (3DCT).

METHODS

The tibial tunnel location in a consecutive series of 35 patients who received a single-bundle ACLR was evaluated by intraoperative navigation system, fluoroscopic image and compared with postoperative 3DCT position. The location to the anterior-posterior (AP) and medial-lateral (ML) direction were compared between all three methods.

RESULTS

The tibial tunnel locations were 46.7 ± 4.5%, 44.5 ± 1.9%, and 43.6 ± 2.4% in ML direction, and 42.8 ± 7.6%, 37.9 ± 3.8%, and 37.9 ± 3.7% in AP direction using an intraoperative navigation system, fluoroscopic image and postoperative 3DCT, respectively. Significant differences between the navigation system and fluoroscopic image (ML, P = 0.001; AP, P = 0.006), and the navigation system and 3DCT (ML, P = 0.001; AP, P < 0.001) were seen. However, there was no significant difference between fluoroscopy and 3DCT (ML, P = 0.315; AP, P = 0.999). There was a significant lack of agreement for analyses measured using a navigation system and 3DCT. Fluoroscopy and 3DCT demonstrated an acceptable agreement (ML, r_pt = -0.21, P = 0.232; AP, r_pt = 0.04, P = 0.826).

CONCLUSIONS

A tibial tunnel location assessed by intraoperative fluoroscopy shows better agreement and interchangeability with one-week postoperative 3DCT validation during single-bundle ACLR compared with an intraoperative image-free navigation system.

Intraoperative fluoroscopy reduces the variability in femoral tunnel placement during single-bundle anterior cruciate ligament reconstruction

PURPOSE

To evaluate the effect of using intraoperative fluoroscopy on femoral and tibial tunnel positioning variability in single-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

A total of 80 consecutive patients with single-bundle ACL reconstruction between 2014 and 2016 were retrospectively reviewed. Among them, 40 underwent ACL reconstruction without fluoroscopy (non-fluoroscopy group) and 40 underwent fluoroscopy-assisted ACL reconstruction (fluoroscopy group). Femoral and tibial tunnel locations were evaluated using a standardized grid system with three-dimensional computed tomography images. Femoral and tibial tunnel location variability was compared between the groups.

RESULTS

The operation time was longer in the fluoroscopy group than in the non-fluoroscopy group (61.3 ± 5.2 min vs. 55.5 ± 4.5 min, p < 0.001). In the fluoroscopy group, a guide pin was repositioned in 16 (40%) cases on the femoral side and 2 (5%) cases on the tibial side. No significant difference in the femoral tunnel location was observed between the fluoroscopy and non-fluoroscopy groups (anterior-posterior plane, 29.0% ± 3.2% vs. 30.0% ± 6.1%; proximal-distal plane, 30.8% ± 4.8% vs. 29.4% ± 8.3%; all parameters,  n.s.); variability was significantly lower in the fluoroscopy group (p < 0.001 for both anterior-posterior and proximal-distal planes). No significant difference in the tibial tunnel location and variability was observed between the fluoroscopy and non-fluoroscopy groups (medial-lateral plane, 45.8% ± 2.0% vs. 46.6% ± 2.4%; anterior-posterior plane, 31.2% ± 4.0% vs. 31.0% ± 5.4%) (all parameters, n.s.).

CONCLUSIONS

Tunnel positioning with fluoroscopic assistance is feasible and effective in achieving consistency in femoral tunnel placement despite a slightly longer operation time. Intraoperative fluoroscopy can be helpful in cases wherein identifying anatomical landmarks on arthroscopy was difficult or for surgeons with less experience who performed ACL reconstruction.

LEVEL OF EVIDENCE

IV.

Do Rotation and Measurement Methods Affect Reliability of Anterior Cruciate Ligament Tunnel Position on 3D Reconstructed Computed Tomography?

Background:

The literature has seldom investigated the anterior cruciate ligament (ACL) tunnel position while considering the effect of rotation of 3-dimensional computed tomography (3D-CT) images during measurements.

Hypothesis:

We hypothesized that (1) measurement of the ACL tunnel position in the femur and tibia through use of 3D-CT is considerably influenced by rotation of the 3D model and (2) there exists a reliable measurement method for ACL tunnel position least affected by rotation.

Study Design:

Controlled laboratory study.

Methods:

The 3D-CT images of 30 randomly selected patients who underwent single-bundle ACL reconstruction were retrospectively reviewed. For femoral tunnel assessments, rectangular reference frames were used that involved the highest point of the intercondylar notch and outer margins of the lateral femoral condyle (method 1), the highest point of the intercondylar notch and outer margins of the lateral wall of the intercondylar notch (method 2), and the lowest point of the intercondylar notch and outer margins of the lateral femoral condyle (method 3). For tibial tunnel assessments, rectangular reference frames with the cortical outline at the articular surface of the tibia (method A) and the cortical outline of the proximal tibia (method B) were used. For both femoral and tibial assessments, the tunnel positions at 5°, 10°, and 15° of rotation of the 3D model were compared with that at a neutral position.

Results:

The values measured by methods 1 and 3 showed significant differences at greater than 5° of rotation compared with the value at the neutral position, whereas method 2 showed relatively consistent results. However, the values measured with both methods A and B showed significant differences at greater than 5° of rotation compared with the value at the neutral position.

Conclusion:

The tunnel position on 3D-CT images was significantly influenced by rotation during measurements. For femoral tunnel position, measurement with a reference frame using the lateral wall of the intercondylar notch (method 2) was the least affected by rotation, with relatively consistent results.

Clinical Relevance:

This study demonstrates that measurement using the lateral wall of the intercondylar notch might be a consistent and reliable method for evaluating the ACL femoral tunnel position considering the effect of 3D-CT image rotation during measurements. However, both methods to measure tibial tunnel position described in this study were similarly affected by rotation.

Femoral offset guide facilitates accurate and precise femoral tunnel placement for single-bundle anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to compare the accuracy and precision of femoral tunnel placement by expert and novice surgeons using an offset guide for single-bundle ACL reconstruction via the anteromedial (AM) portal.

METHODS

Twenty-five single-bundle ACL reconstructions performed by a novice surgeon were matched with 25 ACL reconstructions performed by an expert surgeon, based on one-to-one propensity score matching. The same technique was used by both groups for femoral tunnel placement using a 7-mm offset guide through the AM portal. Using the Bernard and Hertel grid method for postoperative three-dimensional reconstructed computed tomography, the accuracy and precision of various tunnel positions were compared.

RESULTS

No differences were found between the proximal-distal and anterior-posterior femoral tunnel placements by the two groups (proximal-distal; 30.5% involving experts, and 32.5% by novices, n.s) (anterior-posterior; 32.6% involving experts, and 31.6% by novice, n.s). The accuracy of the femoral tunnel positions, based on the average distance from the tunnel center to the center of ACL direct insertion, was similar between the two groups (n.s). No differences were found between the groups in terms of precision of femoral tunnel positions (n.s).

CONCLUSION

Novice surgeons can achieve accuracy and precision comparable to experts in creating femoral tunnels via single-bundle ACL reconstruction through the AM portal using a femoral offset guide. We recommend the use of a femoral offset guide for ACL reconstruction during the learning phase of a novice surgeon for effective tunnel placement to reduce the learning curve required to perform accurate and reproducible ACL reconstruction.

LEVEL OF EVIDENCE

Case-control study, Level III.

Neighborhood Socioeconomic Status Affects Patient-Reported Outcome 2 Years After ACL Reconstruction

Background:

Lower socioeconomic status (SES) is associated with worse patient-reported outcome (PRO) after orthopaedic procedures. In patients with anterior cruciate ligament (ACL) reconstruction, evaluating SES by use of traditional measures such as years of education or occupation is problematic because this group has a large proportion of younger patients. We hypothesized that lower education level and lower values for SES would predict worse PRO at 2 years after ACL reconstruction and that the effect of education level would vary with patient age.

Purpose:

To compare the performance of multivariable models that use traditional measures of SES with models that use an index of neighborhood SES derived from United States (US) Census data.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A cohort of 675 patients (45% female; median age, 20 years), were prospectively enrolled and evaluated 2 years after ACL reconstruction with questionnaires including the International Knee Documentation Committee (IKDC) questionnaire, the Knee injury and Osteoarthritis Outcome Score (KOOS), and the Marx activity rating scale (Marx). In addition, a new variable was generated for this study, the SES index, which used geocoding performed retrospectively to identify the census tract of residence for each participant at the time of enrollment and extract neighborhood SES measures from the 2000 US Census Descriptive Statistics. Multivariable models were constructed that included traditional measures of SES as well as the SES index, and the quality of models was compared through use of the likelihood ratio test.

Results:

Lower SES index was associated with worse PRO for all measures. Models that included the SES index explained more variability than models with traditional SES. In addition, a statistically significant variation was found regarding the impact of education on PRO based on patient age for the IKDC score, the Marx scale, and 4 of the 5 KOOS subscales.

Conclusion:

This study demonstrates that lower neighborhood SES is associated with worse PRO after ACL reconstruction and that age and education have a significant interaction in this patient population. Future studies in patients who have undergone ACL reconstruction should attempt to account for neighborhood SES when adjusting for confounding factors; further, targeting patients from areas with lower neighborhood SES with special interventions may offer an opportunity to improve their outcomes.

Editorial Commentary: From Oslo to MARS and the MOON!: Large Anterior Cruciate Ligament Registries Allow Analyses of Revisions and Re-revisions

Large registry studies are powerful because of inclusion of large numbers of patients. Knee anterior cruciate ligament repeat revision surgery is rare (<10% at 8 years). The reasons require additional investigation. Patients may be counseled that, based on demographic factors, it is difficult to predict who will need re-revision.

Steeper posterior tibial slope correlates with greater tibial tunnel widening after anterior cruciate ligament reconstruction

PURPOSE

To investigate the correlation between posterior tibial slope (PTS) and tibial tunnel widening after anterior cruciate ligament reconstruction (ACL-R).

METHODS

Twenty-five patients underwent anatomic single-bundle ACL-R using quadriceps tendon autograft. Six months after surgery, each patient underwent high-resolution computed tomography (CT). Tibial tunnel aperture location was evaluated using a grid method. Medial and lateral PTS (°) was measured based on a previously described method. To evaluate tibial tunnel widening, cross-sectional area (CSA) of the tibial tunnel beneath the aperture was measured using CT axial slice. Nominal elliptical area was calculated using the diameter of a dilator during the surgery and the angle between the axial slice and the tunnel axis. Percentage of tunnel widening (%) was determined by dividing the CSA by the nominal area. Pearson correlation coefficient was used to explore the association between medial/lateral PTS and tibial tunnel widening (P < 0.05).

RESULTS

Location of tibial tunnel aperture was 29.8 ± 6.3% in anterior-posterior direction, and 45.7 ± 2.1% in medial-lateral direction. Medial and lateral PTS were 3.7° ± 2.5° and 4.9° ± 2.4° respectively. Tibial tunnel widening was 97.2 ± 20.3%. Tibial tunnel widening was correlated with medial PTS (r = 0.558, P = 0.004) and lateral PTS (r = 0.431, P = 0.031).

CONCLUSION

Steeper medial and lateral PTS correlated with greater tibial tunnel widening. The clinical relevance is that surgeons should be aware that PTS may affect tibial tunnel widening after ACL-R. Thus, subjects with steeper PTS may need to be more carefully followed to see if there is greater tibial tunnel widening, which might be important especially in revision ACL-R.

LEVEL OF EVIDENCE

III.

No difference in graft healing or clinical outcome between trans-portal and outside-in techniques after anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to compare femoral tunnel geometry including tunnel position, length, and graft bending angle between trans-portal and outside-in techniques in anterior cruciate ligament (ACL) reconstruction and discover whether such differences in tunnel geometry could influence graft healing or clinical outcome.

METHODS

Sixty-four patients with anatomical single-bundle ACL reconstruction performed with either trans-portal technique (32 patients, one centre) or outside-in technique (32 patients, the other centre) were included in this retrospective study. Femoral tunnel location and length, and graft bending angle at the femoral tunnel were analysed on 3D CT knee model. The location and length of the femoral tunnel and graft bending angle were compared between the two techniques. All patients underwent MRI scans at around 1 year following ACL reconstruction. It was found that all patients had intact ACL graft on MRI images. On oblique axial image taken after ACL reconstruction to determine graft healing at femoral and tibial tunnels and the intra-articular portion, graft signal intensity ratio was calculated by dividing signal intensity (SI) of the reconstructed ACL by that of posterior cruciate ligament (PCL) in the region of interest selected with Marosis software. Clinical outcomes regarding Tegner activity scores, the International Knee Documentation Committee (IKDC) evaluation scores, Lachman test, and pivot shift test results were also compared between the two groups.

RESULTS

While the location of femoral tunnel was similar to each other in both groups, the femoral tunnel length was longer in the outside-in technique (37.0 vs. 32.4 mm, p = .02). Meanwhile, the outside-in technique showed significantly more acute graft tunnel angle than the trans-portal technique (106.7° vs. 113.8°, p = .01). However, signal intensity ratios of grafts (compared with SI of PCL) were similar in femoral and tibial tunnels and intra-articular portions. Moreover, there were no statistically significant differences in terms of IKDC scores (89.4 vs. 90.5, n.s.) or Tegner activity scores (6.2 vs. 6.4, n.s.) between the two groups. There was no significant difference in measurement of Lachman or Pivot shift test either between the two groups.

CONCLUSION

Even though the outside-in technique in ACL reconstruction created a more acute femoral graft bending angle and a longer femoral tunnel length than the trans-portal technique, these had no negative effect on graft healing. In addition, trans-portal and outside-in techniques in ACL reconstruction showed similar femoral tunnel positions and clinical outcomes. Acceptable graft healing and clinical outcomes can be obtained for both trans-portal and outside-in techniques in ACL reconstruction.

LEVEL OF EVIDENCE

III.

To MOON and Back: Lessons Learned and Experience Gained Along the Way

This article highlights the Multicenter Orthopedic Outcomes Network (MOON) study of anterior cruciate ligament reconstruction, from its inception in 1991 to the follow-on studies in progress currently. Lessons learned throughout the process are emphasized.

A Method of Accurate Bone Tunnel Placement for Anterior Cruciate Ligament Reconstruction Based on 3-Dimensional Printing Technology: A Cadaveric Study

PURPOSE

To explore a method of bone tunnel placement for anterior cruciate ligament (ACL) reconstruction based on 3-dimensional (3D) printing technology and to assess its accuracy.

METHODS

Twenty human cadaveric knees were scanned by thin-layer computed tomography (CT). To obtain data on bones used to establish a knee joint model by computer software, customized bone anchors were installed before CT. The reference point was determined at the femoral and tibial footprint areas of the ACL. The site and direction of the bone tunnels of the femur and tibia were designed and calibrated on the knee joint model according to the reference point. The resin template was designed and printed by 3D printing. Placement of the bone tunnels was accomplished by use of templates, and the cadaveric knees were scanned again to compare the concordance of the internal opening of the bone tunnels and reference points.

RESULTS

The twenty 3D printing templates were designed and printed successfully. CT data analysis between the planned and actual drilled tunnel positions showed mean deviations of 0.57 mm (range, 0-1.5 mm; standard deviation, 0.42 mm) at the femur and 0.58 mm (range, 0-1.5 mm; standard deviation, 0.47 mm) at the tibia.

CONCLUSIONS

The accuracy of bone tunnel placement for ACL reconstruction in cadaveric adult knees based on 3D printing technology is high.

CLINICAL RELEVANCE

This method can improve the accuracy of bone tunnel placement for ACL reconstruction in clinical sports medicine.

Location of the tibial tunnel aperture affects extrusion of the lateral meniscus following reconstruction of the anterior cruciate ligament

The anterior root of the lateral meniscus provides functional stability to the meniscus. In this study, we evaluated the relationship between the position of the tibial tunnel and extrusion of the lateral meniscus after anterior cruciate ligament reconstruction, where extrusion provides a proxy measure of injury to the anterior root. The relationship between extrusion and tibial tunnel location was retrospectively evaluated from computed tomography and magnetic resonance images of 26 reconstructed knees, contributed by 25 patients aged 17-31 years. A measurement grid was used to localize the position of the tibial tunnel based on anatomical landmarks identified from the three-dimensional reconstruction of axial computed tomography images of the tibial plateaus. The reference point-to-tibial tunnel distance (mm) was defined as the distance from the midpoint of the lateral edge of the grid to the posterolateral aspect of the tunnel aperture. The optimal cutoff of this distance to minimize post-operative extrusion was identified using receiver operating curve analysis. Extrusion of the lateral meniscus was positively correlated to the reference point-to-tibial tunnel distance (r ²  = 0.64; p < 0.001), with a cutoff distance of 5 mm having a sensitivity to extrusion of 83% and specificity of 93%. The mean extrusion for a distance >5 mm was 0.40 ± 0.43 mm, compared to 1.40 ± 0.51 mm for a distance ≤5 mm (p < 0.001). Therefore, a posterolateral location of the tibial tunnel aperture within the footprint of the anterior cruciate ligament decreases the reference point-to-tibial tunnel distance and increases extrusion of the lateral meniscus post-reconstruction. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1625-1633, 2017.

Outcomes After 1-Stage Versus 2-Stage Revision Anterior Cruciate Ligament Reconstruction

BACKGROUND

Revision anterior cruciate ligament reconstruction (ACLR) is becoming increasingly common as the number of primary ACLR cases continues to rise. Despite this, there are limited data on the outcomes of revision ACLR and even less information specifically addressing the differences in 1-stage revision reconstruction versus those performed in a 2-stage fashion after primary reconstruction.

PURPOSE

To compare the outcomes, patient satisfaction, and failure rates of 1-stage versus 2-stage revision ACLR.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

All patients who underwent revision ACLR between 2010 and 2014 by a single surgeon were collected, and skeletally mature patients over the age of 17 years were included. Patients were excluded if they were skeletally immature; had a previous intra-articular infection in the ipsilateral knee; underwent a prior alignment correction procedure, cartilage repair or transplant procedure, or meniscal allograft transplantation; or had an intra-articular fracture. An ipsilateral or contralateral bone-patellar tendon-bone (BPTB) autograft was the graft of choice. A BPTB allograft was considered for patients aged ≥50 years, for any patient with an insufficient ipsilateral or contralateral patellar tendon, or for those who chose not to have the contralateral patellar tendon graft harvested. Patients completed a subjective questionnaire preoperatively and at a minimum of 2 years postoperatively. Magnetic resonance imaging and computed tomography of all knees were performed preoperatively to assess for associated injuries and to evaluate the ACLR tunnel size and location. Patients with malpositioned tunnels that would critically overlap with an anatomically placed tunnel or those with tunnels ≥14 mm in size underwent bone grafting.

RESULTS

A total of 88 patients met the inclusion criteria for this study. There were 39 patients in the 1-stage revision surgery group (19 male, 20 female) and 49 patients in the 2-stage revision surgery group who underwent tunnel bone grafting first (27 male, 22 female). In both groups, the 12-item Short Form Health Survey (SF-12) Physical Component Summary, Western Ontario and McMaster Universities Arthritis Index, Lysholm, and Tegner activity scale scores significantly improved from preoperatively to postoperatively. There was no significant difference in the SF-12 Mental Component Summary score before and after surgery in either group. Furthermore, there was no significant difference in failure rates or other demographic data between the groups. We observed 4 failures in the 1-stage reconstruction group (10.3%) and 3 failures in the 2-stage reconstruction group (6.1%).

CONCLUSION

In this study, objective outcomes and subjective patient scores and satisfaction were not significantly different between 1-stage and 2-stage revision ACLRs. Both groups had significantly improved objective outcomes and patient subjective outcomes without notable differences in failure rates. Further longitudinal studies comparing 1-stage and 2-stage revision ACLRs over a longer time frame are recommended.

ACL Roof Impingement Revisited: Does the Independent Femoral Drilling Technique Avoid Roof Impingement With Anteriorly Placed Tibial Tunnels?

Background:

Anatomic femoral tunnel placement for single-bundle anterior cruciate ligament (ACL) reconstruction is now well accepted. The ideal location for the tibial tunnel has not been studied extensively, although some biomechanical and clinical studies suggest that placement of the tibial tunnel in the anterior part of the ACL tibial attachment site may be desirable. However, the concern for intercondylar roof impingement has tempered enthusiasm for anterior tibial tunnel placement.

Purpose:

To compare the potential for intercondylar roof impingement of ACL grafts with anteriorly positioned tibial tunnels after either transtibial (TT) or independent femoral (IF) tunnel drilling.

Study Design:

Controlled laboratory study.

Methods:

Twelve fresh-frozen cadaver knees were randomized to either a TT or IF drilling technique. Tibial guide pins were drilled in the anterior third of the native ACL tibial attachment site after debridement. All efforts were made to drill the femoral tunnel anatomically in the center of the attachment site, and the surrogate ACL graft was visualized using 3-dimensional computed tomography. Reformatting was used to evaluate for roof impingement. Tunnel dimensions, knee flexion angles, and intra-articular sagittal graft angles were also measured. The Impingement Review Index (IRI) was used to evaluate for graft impingement.

Results:

Two grafts (2/6, 33.3%) in the TT group impinged upon the intercondylar roof and demonstrated angular deformity (IRI type 1). No grafts in the IF group impinged, although 2 of 6 (66.7%) IF grafts touched the roof without deformation (IRI type 2). The presence or absence of impingement was not statistically significant. The mean sagittal tibial tunnel guide pin position prior to drilling was 27.6% of the sagittal diameter of the tibia (range, 22%-33.9%). However, computed tomography performed postdrilling detected substantial posterior enlargement in 2 TT specimens. A significant difference in the sagittal graft angle was noted between the 2 groups. TT grafts were more vertical, leading to angular convergence with the roof, whereas IF grafts were more horizontal and universally diverged from the roof.

Conclusion:

The IF technique had no specimens with roof impingement despite an anterior tibial tunnel position, likely due to a more horizontal graft trajectory and anatomic placement of the ACL femoral tunnel. Roof impingement remains a concern after TT ACL reconstruction in the setting of anterior tibial tunnel placement, although statistical significance was not found. Future clinical studies are planned to develop better recommendations for ACL tibial tunnel placement.

Clinical Relevance:

Graft impingement due to excessively anterior tibial tunnel placement using a TT drilling technique has been previously demonstrated; however, this may not be a concern when using an IF tunnel drilling technique. There may also be biomechanical advantages to a more anterior tibial tunnel in IF tunnel ACL reconstruction.

Anatomic ACL reconstruction: the normal central tibial footprint position and a standardised technique for measuring tibial tunnel location on 3D CT

PURPOSE

The aim of this study was to define the normal ACL central tibial footprint position and describe a standardised technique of measuring tibial tunnel location on 3D CT for anatomic single-bundle ACL reconstruction.

METHODS

The central position of the ACL tibial attachment site was determined on 76 MRI scans of young individuals. The central footprint position was referenced in the anterior-posterior (A-P) and medial-lateral (M-L) planes on a grid system over the widest portion of the proximal tibia. 3D CT images of 26 young individuals had a simulated tibial tunnel centred within the bony landmarks of the ACL footprint, and the same grid system was applied over the widest portion of the proximal tibia. The MRI central footprint position was compared to the 3D CT central footprint position to validate the technique and results.

RESULTS

The median age of the 76 MRI subjects was 24 years, with 32 females and 44 males. The ACL central footprint position was at 39 (±3 %) and 48 (±2 %), in the A-P and M-L planes, respectively. There was no significant difference in this position between sexes. The median age of the 26 CT subjects was 25.5 years, with 10 females and 16 males. The central position of the bony ACL footprint was at 38 (±2 %) and 48 (±2 %), in the A-P and M-L planes, respectively. The MRI and CT central footprint positions were not significantly different in relation to the medial position, but were different in relation to the anterior position (A-P 39 % vs. 38 %, p = 0.01). The absolute difference between the central MRI and CT reference positions was 0.45 mm.

CONCLUSIONS

The ACL's normal central tibial footprint reference position has been defined, and the technique of measuring tibial tunnel location with a standardised grid system is described. This study will assist surgeons in evaluating tibial tunnel position in anatomic single-bundle ACL reconstruction.

LEVEL OF EVIDENCE

III.

Comparison of tunnel variability between trans-portal and outside-in techniques in ACL reconstruction

PURPOSE

Although trans-portal and outside-in techniques are commonly used for anatomical ACL reconstruction, there is very little information on variability in tunnel placement between two techniques.

METHODS

A total of 103 patients who received ACL reconstruction using trans-portal (50 patients) and outside-in techniques (53 patients) were included in the study. The ACL tunnel location, length and graft-femoral tunnel angle were analyzed using the 3D CT knee models, and we compared the location and length of the femoral and tibial tunnels, and graft bending angle between the two techniques. The variability in each technique regarding the tunnel location, length and graft tunnel angle using the range values was also compared.

RESULTS

There were no differences in the average of femoral tunnel depth and height between the two groups. The ranges of femoral tunnel depth and height showed no difference between two groups (36 and 41 % in trans-portal technique vs. 32 and 41 % in outside-in technique). The average value and ranges of tibial tunnel location also showed similar results in two groups. The outside-in technique showed longer femoral tunnel than the trans-portal technique (34.0 vs. 36.8 mm, p = 0.001). The range of femoral tunnel was also wider in trans-portal technique than in outside-in technique. Although the outside-in technique showed significant acute graft bending angle than trans-portal technique in average values, the trans-portal technique showed wider ranges in graft bending angle than outside-in technique [ranges 73° (SD 13.6) vs. 53° (SD 10.7), respectively].

CONCLUSIONS

Although both trans-portal and outside-in techniques in ACL reconstruction can provide relatively consistent in femoral and tibial tunnel locations, trans-portal technique showed high variability in femoral tunnel length and graft bending angles than outside-in technique. Therefore, the outside-in technique in ACL reconstruction is considered as the effective method for surgeons to make more consistent femoral tunnel.

LEVEL OF EVIDENCE

III.

Overlap Between Anterior Cruciate Ligament and Anterolateral Meniscal Root Insertions: A Scanning Electron Microscopy Study

BACKGROUND

The anterolateral meniscal root (ALMR) has been reported to intricately insert underneath the tibial insertion of the anterior cruciate ligament (ACL). Previous studies have begun to evaluate the relationship between the insertion areas and the risk of iatrogenic injuries; however, the overlap of the insertions has yet to be quantified in the sagittal and coronal planes.

PURPOSE

To investigate the insertions of the human tibial ACL and ALMR using scanning electron microscopy (SEM) and to quantify the overlap of the ALMR insertion in the coronal and sagittal planes.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten cadaveric knees were dissected to isolate the tibial ACL and ALMR insertions. Specimens were prepared and imaged in the coronal and sagittal planes. After imaging, fiber directions were examined to identify the insertions and used to calculate the percentage of the ACL that overlaps with the ALMR instead of inserting into bone.

RESULTS

Four-phase insertion fibers of the tibial ACL were identified directly medial to the ALMR insertion as they attached onto the tibial plateau. The mean percentage of ACL fibers overlapping the ALMR insertion instead of inserting into subchondral bone in the coronal and sagittal planes was 41.0% ± 8.9% and 53.9% ± 4.3%, respectively. The percentage of insertion overlap in the sagittal plane was significantly higher than in the coronal plane ( P = .02).

CONCLUSION

This study is the first to quantify the ACL insertion overlap of the ALMR insertion in the coronal and sagittal planes, which supplements previous literature on the insertion area overlap and iatrogenic injuries of the ALMR insertion. Future studies should determine how much damage to the ALMR insertion is acceptable to properly restore ACL function without increasing the risk for tears of the ALMR.

CLINICAL RELEVANCE

Overlap of the insertion areas on the tibial plateau has been previously reported; however, the results of this study demonstrate significant overlap of the insertions superior to the insertion sites on the tibial plateau as well. These findings need to be considered when positioning for tibial tunnel creation in ACL reconstruction to avoid damage to the ALMR insertion.

The learning curve associated with anteromedial portal drilling in ACL reconstruction

OBJECTIVES

The objective of the current study was to evaluate the accuracy and precision of femoral and tibial tunnel placement during anterior cruciate ligament reconstruction (ACLR) using independent anteromedial portal (AMP) drilling over a three-year observation period.

METHODS

This study was a retrospective review of 161 consecutive primary ACL reconstructions from a single surgeon over his first 36-months in practice. Femoral and tibial tunnel angulation measurements were made on anteroposterior radiographs by a single observer utilizing the assessment method described by Aglietti et al. The accuracy and precision of tunnel placement across the three-year period were assessed with comparisons made.

RESULTS

Significantly improved accuracy was demonstrated toward the cadaveric ideal femoral tunnel angle of 33.5° over time. Improved precision of tunnel placement was also demonstrated evidenced by declining standard deviations across each year. Statistically significant improvement in femoral tunnel placement was seen between the first and second cohorts of 32 cases. No significant change was seen with respect to tibial tunnel angle across the observation period.

CONCLUSIONS

A learning curve in developing accuracy and precision in ACL femoral tunnel placement using the AMP technique exists; our study indicates this to be somewhere between 32 and 64 cases. Tibial tunnel placement does not share the same learning curve using this surgical technique.

A prospective evaluation of the anterior horn of the lateral meniscus as a landmark for tibial tunnel placement in anterior cruciate ligament (ACL) reconstruction

BACKGROUND

The goal of this study was to prospectively evaluate the accuracy and consistency of the anterior horn of the lateral meniscus as a landmark in achieving the desired tibial tunnel location during primary anterior cruciate ligament (ACL) reconstruction.

METHODS

One hundred consecutive adult patients undergoing primary ACL reconstruction were enrolled in the study. One sports-fellowship trained surgeon performed all ACL reconstructions using independent tunnel drilling with an accessory anteromedial portal for the femoral tunnel. All guide pins for the tibial tunnel were placed using a 55-degree guide using the posterior border of the anterior horn of the lateral meniscus as a landmark. Following pin placement, a true lateral fluoroscopic image was obtained. These were digitally analyzed to measure the location of the pin along the length of the tibial plateau.

RESULTS

The average anteroposterior (A-P) distance achieved using the posterior border of the anterior horn of the lateral meniscus as a landmark for tibial tunnel placement was 37.0%±5.2% (mean±standard deviation) [range 26.4%-49.2%]. 66% of tibial tunnels were located between 30.0% and 39.9% of the A-P tibial distance. Only 18% of tibial tunnels localized between 40.0% and 44.9%, the area of the anatomic footprint described by Staubli and Rauschning [9] 16% of patients were significant outliers, with tunnels localizing to 25.0%-29.9% (6 patients) or 45.0%-49.9% (10 patients).

CONCLUSIONS

Use of the posterior border of the anterior horn of the lateral meniscus as a landmark for tibial tunnel placement during anatomic ACL reconstruction yields an inconsistent tunnel location.

LEVEL OF EVIDENCE

II, Prospective study.

The effect of feedback from post-operative 3D CT on placement of femoral tunnels in single-bundle anatomic ACL reconstruction

PURPOSE

To evaluate the effect of feedback from post-operative 3D CT in the learning process of placing the femoral graft tunnel anatomically using the anteromedial (AM)-portal technique in single-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

An experienced knee surgeon converting from transtibial to AM-portal technique was offered post-operative feedback on tunnel placement. Three groups of patients were included: transtibial drilling, (AM1) anteromedial drilling without feedback and (AM2) anteromedial drilling with post-operative CT feedback. Intra-articular landmarks were used as the only guidance for tunnel placement. Tunnel position was compared to an ideal anatomical ACL position using the Bernard and Hertel grid and visual feedback was given on tunnel placements. The effect of feedback was measured as the distance from the anatomical centre, and spread of tunnel placements on post-operative CT performed feedback was initiated.

RESULTS

When comparing the femoral tunnel placement to an ideal anatomical centre, there was an improvement in the mean tunnel position after (A) changing from a transtibial to an anatomical technique and a further improvement after (B) initializing the radiological feedback. There was a great variation of femoral tunnel localizations when initially only using intra-articular landmarks as guidance for tunnel placement--this variation, however, converged towards the anatomical centre throughout the feedback period and the AM2 group had a femoral tunnel closer (P = 0.001) to the anatomical centre than the AM1 group.

CONCLUSIONS

Post-operative 3D CT is effective in the learning process of placing femoral tunnels anatomically by giving post-operative feedback on tunnel placement. Bony landmarks and ACL remnants were found unreliable as the only guidance for femoral tunnel placement in the AM-portal technique-therefore, the use of an aid is recommended to reduce unwanted tunnel variations in a learning phase.

LEVEL OF EVIDENCE

Cohort Study, Level III.

The role of computer assisted navigation in revision surgery for failed anterior cruciate ligament reconstruction of the knee: A continuous series of 52 cases

INTRODUCTION

The causes of failure of anterior cruciate ligament (ACL) reconstruction mainly involve incorrect tunnel positioning. There is no intraoperative tool allowing the surgeon to test graft biomechanics and to confirm that the new graft is in an optimal position.

HYPOTHESIS

Control is improved with computer assisted navigation.

MATERIAL AND METHODS

In this retrospective study, revision ACL reconstruction was performed with a new autologous graft in a continuous series of 52 failed ACL reconstructions. A computer assisted navigation system was used intraoperatively in all knees. Evaluation with this system confirmed the position of old and new tunnels as well as intraoperative laxity.

RESULTS

Evaluation of tunnel position based on traditional radiological criteria found in the literature significantly underestimated graft biomechanics: 69% of the cases presented with unfavorable graft ansiometry (mean: 13 ± 2.2mm) while the correct position of the tibial tunnel was identified in 64% of cases on radiography and the femoral tunnel in 48%. All new grafts were optimally positioned by the computer assisted navigation system with a mean isometery of 3.2 (± 0.7) mm. Comparative pre- and postoperative evaluation of laxity showed a statistically significant improvement (P < 0.001): preoperative and postoperative Lachman test: 10.5 ± 2 mm and 3 ± 0.5, respectively; global rotational laxity: 24 ± 5° and 37 ± 7° respectively.

CONCLUSION

The use of a computer assisted navigation system allows optimal positioning of the graft as well as a predictive assessment of laxity.

Variability of tunnel positioning in fluoroscopic-assisted ACL reconstruction

PURPOSE

Intraoperative fluoroscopy has been proposed as a feasible method to improve the accuracy of anatomical tunnel positioning. However, it has so far not been determined, whether this technique reduces the variability of tunnel positioning in a clinical set-up. Therefore, the purpose of this study was to determine the variability of tunnel positions applying intraoperative fluoroscopy.

METHODS

Femoral and tibial tunnel positions of 112 fluoroscopic ACL reconstruction cases were determined according to validated radiological measurement methods. Mean positions, standard deviations and ranges were calculated to determine the variability of the tunnel positions. Subgroup variability analysis was performed to analyse cases in which tunnel positions were corrected.

RESULTS

Applying intraoperative fluoroscopy, the variability of tunnel positions was found to be 3 % at the femur (range 15.4 %) and 2.3 % at the tibia (9.7 %). In 34 cases (30.0 %), non-satisfactory tunnel positions were identified and could be corrected achieving more accurate positions regarding to radiological parameters (14× femur, 16× tibia, 4× femur and tibia).

CONCLUSIONS

The results of the presented study indicate that intraoperative fluoroscopy allows to identify non-accurate tunnel positions regarding to radiological criteria. The determined low variability indicates that fluoroscopic-based ACL reconstruction can be recommended as a feasible, easy and effective adjunct that enables surgeons to create more consistent and reliable tunnel positions in ACL reconstruction.

LEVEL OF EVIDENCE

IV.

The Impact of the Multicenter Orthopaedic Outcomes Network (MOON) Research on Anterior Cruciate Ligament Reconstruction and Orthopaedic Practice

With an estimated 200,000 anterior cruciate ligament reconstructions performed annually in the United States, there is an emphasis on determining patient-specific information to help educate patients on expected clinically relevant outcomes. The Multicenter Orthopaedic Outcomes Network consortium was created in 2002 to enroll and longitudinally follow a large population cohort of anterior cruciate ligament reconstructions. The study group has enrolled >4,400 anterior cruciate ligament reconstructions from seven institutions to establish the large level I prospective anterior cruciate ligament reconstruction outcomes cohort. The group has become more than a database with information regarding anterior cruciate ligament injuries; it has helped to establish a new benchmark for conducting multicenter, multisurgeon orthopaedic research. The changes in anterior cruciate ligament reconstruction practice resulting from the group include the use of autograft for high school, college, and competitive athletes in their primary anterior cruciate ligament reconstructions. Other modifications include treatment options for meniscus and cartilage injuries, as well as lifestyle choices made after anterior cruciate ligament reconstruction.

Multirater agreement of the causes of anterior cruciate ligament reconstruction failure: a radiographic and video analysis of the MARS cohort

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction failure occurs in up to 10% of cases. Technical errors are considered the most common cause of graft failure despite the absence of validated studies. Limited data are available regarding the agreement among orthopaedic surgeons regarding the causes of primary ACL reconstruction failure and accuracy of graft tunnel placement.

HYPOTHESIS

Experienced knee surgeons have a high level of interobserver reliability in the agreement about the causes of primary ACL reconstruction failure, anatomic graft characteristics, and tunnel placement.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

Twenty cases of revision ACL reconstruction were randomly selected from the Multicenter ACL Revision Study (MARS) database. Each case included the patient's history, standardized radiographs, and a concise 30-second arthroscopic video taken at the time of revision demonstrating the graft remnant and location of the tunnel apertures. All 20 cases were reviewed by 10 MARS surgeons not involved with the primary surgery. Each surgeon completed a 2-part questionnaire dealing with each surgeon's training and practice, as well as the placement of the femoral and tibial tunnels, condition of the primary graft, and the surgeon's opinion as to the causes of graft failure. Interrater agreement was determined for each question with the kappa coefficient and the prevalence-adjusted, bias-adjusted kappa (PABAK).

RESULTS

The 10 reviewers have been in practice an average of 14 years and have performed at least 25 ACL reconstructions per year, and 9 were fellowship trained in sports medicine. There was wide variability in agreement among knee experts as to the specific causes of ACL graft failure. When participants were specifically asked about technical error as the cause for failure, interobserver agreement was only slight (PABAK = 0.26). There was fair overall agreement on ideal femoral tunnel placement (PABAK = 0.55) but only slight agreement on whether a femoral tunnel was too anterior (PABAK = 0.24) and fair agreement on whether it was too vertical (PABAK = 0.46). There was poor overall agreement for ideal tibial tunnel placement (PABAK = 0.17).

CONCLUSION

This study suggests that more objective criteria are needed to accurately determine the causes of primary ACL graft failure as well as the ideal femoral and tibial tunnel placement in patients undergoing revision ACL reconstruction.

Factors affecting return to play after anterior cruciate ligament reconstruction: a review of the current literature

Anterior cruciate ligament reconstruction has been reported to produce normal or near-normal knee results in > 90% of patients. A recent meta-analysis suggested that, despite normal or near-normal knees, many athletes do not return to sports. Rates and timing of return to competitive athletics are quite variable depending on the graft type, the age of the patient, the sport, and the level of play. Even when athletes do return to play, often they do not return to their previous level. Graft failure, subjective physical factors, and psychological factors, including fear of reinjury and lack of motivation, appear to play a large role in patients' ability to return to sporting activities.