Notchplasty in anterior cruciate ligament reconstruction in the setting of passive anterior tibial subluxation

High-grade pivot-shift phenomenon after anterior cruciate ligament injury is associated with asymmetry of lateral and medial compartment anterior tibial translation and lateral meniscus posterior horn tears

PURPOSE

To investigate whether the high-grade pivot-shift phenomenon is associated with asymmetry of the lateral and medial compartment anterior tibial translation (L-ATT and M-ATT) and lateral meniscus posterior horn (LMPH) tears in anterior cruciate ligament (ACL) injuries.

METHODS

A retrospective analysis was performed on 192 consecutive patients who had complete ACL injuries between January 2019 and December 2020. Among these, 156 met the inclusion criteria. L-ATT and M-ATT were measured using preoperative weight-bearing magnetic resonance imaging (MRI), and the differences between L-ATT and M-ATT were calculated. Thirty-five patients who demonstrated excessive differences in L-ATT and M-ATT (> 6.0 mm) were regarded as asymmetric (study group), and 36 patients with minimal or no differences in L-ATT and M-ATT (< 3.0 mm) were allocated to the control group. Demographic data, grade of the pivot-shift test, integrality of LMPH, and medial meniscus posterior horn (MMPH) were compared between the groups. Moreover, predictors of high-grade pivot-shift phenomenon, including asymmetry of L-ATT and M-ATT, integrity of LMPH and MMPH, time from injury to surgery, sex, age, and body mass index (BMI) were assessed using multivariable logistic regression analysis.

RESULTS

The difference between L-ATT and M-ATT in the study group was significantly higher than that in the control group (mean ± SD: 8.4 ± 2.1 mm vs. 1.5 ± 1.0 mm, P < 0.001). A higher proportion of patients with high-grade pivot-shift phenomenon (2 + and 3 +) and LMPH tears were identified in the study group (high-grade pivot-shift phenomenon: 25/35 vs. 13/36, P = 0.003; LMPH tears: 18/35 vs. 5/36, P = 0.001). Additionally, asymmetry of L-ATT, M-ATT (odds ratio 5.8; 95% CI 1.7-19.8; P = 0.005), and LMPH tears (odds ratio 3.8; 95% CI 1.3-11.6; P = 0.018) were found to be good predictors of the high-grade pivot-shift phenomenon after ACL injury, whereas MMPH tears, time from injury to surgery, sex, age, and BMI were not.

CONCLUSION

In patients with ACL injury, the high-grade pivot-shift phenomenon is associated with asymmetry between L-ATT and M-ATT, and LMPH tears.

LEVEL OF EVIDENCE

III.

Preoperative excessive lateral anterior tibial subluxation is related to posterior tibial tunnel insertion with worse sagittal alignment after anterior cruciate ligament reconstructions

Objective

To investigate whether preoperative lateral anterior tibial subluxation (LATS) measured from magnetic resonance imaging (MRI) can influence tibial insertion and postoperative sagittal alignment after anterior cruciate ligament reconstructions (ACLRs).

Methods

84 patients who underwent single-bundle ACLRs were retrospectively investigated. Among them, 39 patients (LATS of <6 mm) 23 patients (LATS of ≥6 mm and <10 mm) and 22 patients (excessive LATS of ≥10 mm) were defined as group 1, 2 and 3, respectively. LATS, the position of graft insertion into tibia as ratio of anterior-posterior width (AP ratio) and the sagittal graft angle (SGA) were postoperatively assessed from MRI at 2-year follow-up. Following linear regression analyses were employed.

Results

The group 3 exhibited the largest preoperative LATS and remained the most postoperative LATS. Moreover, the group 3 possessed the most posteriorly located tunnel insertion with the largest AP ratio and the most vertical graft orientation. Of all included patients, a moderate correlation was demonstrated between pre- and postoperative LATS (r = 0.635). A low correlation was observed between preoperative LATS and AP ratio (r = 0.300) and a moderate correlation was displayed between AP ratio and SGA (r = 0.656).

Conclusion

For ACL injuries with excessive LATS (≥10 mm), most posteriorly located tibial insertion was found out, and worse sagittal alignment containing high residual LATS was associated with more vertical graft orientation following ACLRs.

Transtibial pull-out repair of lateral meniscus posterior root is beneficial for graft maturation after anterior cruciate ligament reconstruction: a retrospective study

PURPOSE

To determine the repair of LMPR lesions would improve the ACL graft maturation.

METHOD

A total of 49 patients underwent ACL reconstruction were included in this study. Patients were furtherly sub-grouped according to the status of LMPR: intact (17), repair (16) and resected (16). Assessments performed pre- and 2 years post-operatively included patients-reported scores and arthrometer side-to-side difference. Magnetic resonance imaging was used 2 years after the surgery to compare the lateral meniscal extrusion (LME), anterior tibial subluxation of the medial compartment (ATSMC), anterior tibial subluxation of the lateral compartment (ATSLC), the difference of ATSMC and ATSLC, and signal/noise quotient (SNQ) of ACL graft.

RESULTS

In LMPR resected group, it showed greater post-operative ATSMC-ATSLC difference when compared with pre-operatively (P = 0.006) and with the other 2 groups (intact: P = 0.031; repair: P = 0.048). SNQ of ACL graft was higher in LMPR resected group than those in LMPR intact (P = 0.004) and repair group (P = 0.002). The LMPR repair group showed significant reduction in LME post-operatively (P = 0.001). Post-operative measures on ATSLC-ATSMC difference (β = 0.304, P = 0.049) and LME (β = 0.492, P = 0.003) showed significant association with graft SNQ.

CONCLUSIONS

Transtibial repair of LMPR concomitant with ACL reconstruction restored translational stability, reduced meniscus extrusion, making it beneficial for ACL graft maturation.

Anterior cruciate ligament femoral-tunnel drilling through an anteromedial portal: 3-dimensional plane drilling angle affects tunnel length relative to notchplasty

Background

Notchplasty is a surgical technique often performed during anterior cruciate ligament reconstruction (ACLR) with widening of the intercondylar notch of the lateral distal femur to avoid graft impingement. The purpose of this study was to correlate femoral-tunnel length with 3-dimensional (3D) drilling angle through the anteromedial (AM) portal with and without notchplasty.

Materials and methods

Computer data were collected from an anatomical study using 16 cadaveric knees. The anterior cruciate ligament (ACL) femoral insertion was dissected and outlined for gross anatomical observation. The dissected cadaveric knees were scanned by computed tomography (CT). Three-dimensional measurements were calculated using software (Geomagic, Inc., Research Triangle Park, NC, USA) and included the center of the ACL footprint and the size of the ACL femoral footprint. The femoral-tunnel aperture centers were measured in the anatomical posterior-to-anterior and proximal-to-distal directions using Bernard’s quadrant method. The ACL tunnel was created 3-demensionally in the anatomical center of femoral foot print of ACL using software (SolidWorks®, Corp., Waltham, MA, USA). The 8-mm cylinder shaped ACL tunnel was rested upon the anatomical center of the ACL footprint and placed in three different positions: the coronal plane, the sagittal plane, and the axial plane. Finally, the effect of notchplasty on the femoral-tunnel length and center of the ACL footprint were measured. All the above-mentioned studies performed ACLR using the AM portal.

Results

The length of the femoral tunnels produced using the low coronal and high axial angles with 5-mm notchplasty became significantly shorter as the femoral starting position became more horizontal. The result was 30.38 ± 2.11 mm on average at 20° in the coronal plane/70° in the axial plane/45° in the sagittal plane and 31.26 ± 2.08 mm at 30° in the coronal plane/60° in the axial plane/45° in the sagittal plane, respectively, comparing the standard technique of 45° in the coronal/45° in the axial/45° in the sagittal plane of 32.98 ± 3.04 mm (P < 0.001). The tunnels made using the high coronal and low axial angles with notchplasty became longer than those made using the standard technique: 40.31 ± 3.36 mm at 60° in the coronal plane/30° in the axial plane/45° in the sagittal plane and 50.46 ± 3.13 mm at 75° in the coronal plane/15° in the axial plane/45° in the sagittal plane (P < 0.001).

Conclusions

Our results show that excessive notchplasty causes the femoral tunnel to be located in the non-anatomical center of the ACL footprint and reduces the femoral-tunnel length. Therefore, care should be taken to avoid excessive notchplasty when performing this operation.

Pre-operative Static Anterior Tibial Translation Assessed on MRI Does Not Influence Return to Sport or Satisfaction After Anterior Cruciate Ligament Reconstruction

BACKGROUND

It has been suggested that the degree of anterior tibial translation (ATT) as measured passively on imaging studies (static ATT) after an anterior cruciate ligament (ACL) injury may influence outcomes after ACL reconstruction. However, there is a lack of evidence supporting these suggestions.

QUESTIONS/PURPOSES

The purpose of this retrospective prognostic study was to assess the predictive value of pre-operative static ATT in knees with ACL injury on return to sport and in satisfaction after ACL reconstruction. Our hypothesis was that greater static ATT would be associated with lower rates of return to sport and lower levels of satisfaction.

METHODS

Patients treated with ACL reconstruction were identified from an institutional registry and assigned to one of three groups according to their ACL injury type: acute ACL injury, chronic ACL injury, and failed ACL reconstruction. ATT in each knee compartment was measured using magnetic resonance imaging, and a retrospective telephone questionnaire was used to investigate post-ACL reconstruction return to sport and subjects' satisfaction.

RESULTS

One hundred thirty patients (52 acute with ACL injury, 29 with chronic ACL injury, and 49 with failed ACL reconstruction) completed the questionnaire, with a mean follow-up of 5.67 years. Ninety-seven patients (74.6%) returned to their primary sport, of whom 63 (65%) returned to the same level of sport. The mean time to return to sport was 10.1 months (range, 2 to 24 months). Overall, 113 patients (87%) were either very satisfied or satisfied with their outcomes. No difference in medial or lateral ATT was found between patients who returned to sport and those who did not. The failed-ACL reconstruction group had significantly lower rates of return to sport than did acutely and chronically injured patients (60.4% versus 88.5% and 75.9%, respectively).

CONCLUSION

The degree of pre-operative ATT in an ACL-deficient knee was not correlated with return to sport or satisfaction after ACL reconstruction. In this study cohort, only failed-ACL reconstruction patients undergoing revision ACL reconstruction were significantly less likely to return to their main sport. They were also less likely to return to sport at their pre-operative level, if they did return to sport.

Lateral Meniscus Posterior Root Lesion Influences Anterior Tibial Subluxation of the Lateral Compartment in Extension After Anterior Cruciate Ligament Injury

BACKGROUND

The lateral meniscus posterior root (LMPR) lesion further decreases dynamic knee stability after anterior cruciate ligament (ACL) injury owing to the loss of the "wedge effect" maintained by the posterior horn of the lateral meniscus. However, the effect of LMPR lesions on the static tibiofemoral relationship in extension after ACL injuries is not determined.

PURPOSE

To (1) determine the effect of LMPR lesions on anterior tibial subluxation of the lateral compartment (ATSLC) in extension in patients with ACL injuries and to (2) identify the LMPR-related factors associated with excessive ATSLC in extension.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Between January 2015 and December 2017, 405 consecutive patients with diagnosed ACL injuries who underwent primary ACL reconstructions were retrospectively reviewed. Among them, 45 patients with combined ACL injuries and LMPR lesions (ACL+LMPR group) and 51 patients with isolated ACL injuries (ACL group) were identified. Values of ATSLC in extension were measured on preoperative supine magnetic resonance imaging and classified into high grade (≥6 mm) and low grade (<6 mm). The mean ATSLC in extension and the proportion of patients with high-grade ATSLC in extension were compared between the groups by univariate analysis. In the ACL+LMPR group, predictors of high-grade ATSLC in extension-including age, sex, body mass index, affected side, cause of injury, period from injury (<12 or ≥12 weeks), LMPR lesion pattern (radial tear or root avulsion), and meniscofemoral ligament integrity (intact or impaired)-were assessed by univariate analysis and multivariate logistic regression analysis.

RESULTS

The mean ATSLC in extension in the ACL+LMPR group was significantly greater than that in the ACL group (5.6 mm vs 3.1 mm; P = .001). The proportion of patients with high-grade ATSLC in extension in the ACL+LMPR group was also significantly larger than that in the ACL group (44.4% vs 15.7%; P = .002). In addition, the root avulsion (instead of radial tear) (odds ratio, 28.750; 95% CI, 2.344-352.549; P = .009) and the period from injury ≥12 weeks (odds ratio, 17.095; 95% CI, 1.207-242.101; P = .036) were determined to be the 2 independent predictors of high-grade ATSLC in extension. However, age, sex, body mass index, affected side, cause of injury, and meniscofemoral ligament integrity were not.

CONCLUSION

After ACL injuries, concomitant LMPR lesion further increased ATSLC in extension. Chronic LMPR avulsion was associated with high-grade ATSLC in extension.

Excessive Preoperative Anterior Tibial Subluxation in Extension Is Associated With Inferior Knee Stability After Anatomic Anterior Cruciate Ligament Reconstruction

BACKGROUND

Anterior tibial subluxation (ATS) in extension after anterior cruciate ligament (ACL) injury highlights an increased anterior position of the tibia relative to the femur. Recent studies demonstrated that subluxation is sometimes irreducible and the normal tibiofemoral relationship is not restored by ACL reconstruction (ACLR), which raises concerns regarding clinical outcomes after ACLR.

HYPOTHESIS

Excessive preoperative ATS in extension is associated with inferior knee stability after anatomic ACLR.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

From March 2016 to January 2017, a total of 487 consecutive patients with clinically diagnosed noncontact ACL injuries who underwent primary anatomic ACLR were retrospectively analyzed. Of these patients, 430 met the criteria for inclusion in this study. Anterior subluxation of the lateral and medial compartments (ASLC and ASMC) in extension relative to the femoral condyles was measured on preoperative magnetic resonance imaging. Twenty patients (study group) who demonstrated excessive (>10 mm) ASLC and ASMC in extension were matched 1:2 to 40 participants (control group) who showed minimal or no (<3 mm) ASLC and ASMC in extension. The amount of ASLC and ASMC in extension relative to the femoral condyles at 2 years postoperatively was the primary outcome. Moreover, the Lysholm score, IKDC grade (International Knee Documentation Committee), and stability assessments (pivot-shift test and KT-1000 arthrometer side-to-side difference) were evaluated preoperatively and at the last follow-up visit.

RESULTS

The preoperative mean ASLC and ASMC in extension of the study group were both significantly larger than those of the control group (study group vs control group: ASLC, 13.5 mm vs 1.2 mm; ASMC, 12.4 mm vs 1.0 mm; P < .05). Moreover, patients in the study group showed significantly larger posterior tibial slope than the patients in the control group (17.8°± 2.5° vs 9.5°± 1.5°; P < .05). At the final follow-up visit, the mean ASLC and ASMC of the study group were 8.1 mm and 7.3 mm, which were significantly larger than those of the control group (ASLC, 0.9 mm; ASMC, 0.7 mm; P < .05). In addition, the study group showed inferior knee stability when compared with the control group in terms of both the pivot-shift test (study group vs control group: 2 grade 2, 10 grade 1, and 8 grade 0 vs 1 grade 1 and 39 grade 0; P < .05) and the KT-1000 arthrometer side-to-side difference (study group vs control group: 4.4 ± 1.2 mm vs 1.5 ± 0.6 mm; P < .05). Furthermore, the study group showed significantly lower mean Lysholm score (study group vs control group: 80.3 ± 6.3 vs 93.3 ± 4.3, P < .05) and IKDC grading results (study group vs control group: 3 grade C, 16 grade B, and 1 grade A vs 3 grade B and 37 grade A; P < .05) as compared with the control group.

CONCLUSION

In this short-term study, the excessive (>10 mm) preoperative ATS in extension after ACL injury was associated with inferior knee stability after anatomic ACLR.

Notchplasty alters knee biomechanics after anatomic ACL reconstruction

PURPOSE

The aims of this study were (1) to study the biomechanics of single-bundle anatomic ACL reconstructed knees with and without notchplasty using a robotic testing system and (2) to determine if there would be a difference between performing a small or large notchplasty.

METHODS

Fifteen fresh-frozen specimens were used in this study. The ACL reconstruction (ACL-R) was performed using an anatomic single-bundle technique with the 8 mm soft tissue graft fixed at 30° with suspensory fixation on the femoral side and a screw and washer on the tibial side. The notchplasty was then created with a burr. The following knee states were compared: (1) ACL-R, (2) ACL-R with a small (3 mm) notchplasty, and (3) ACL-R with a large (6 mm) notchplasty. Four loading conditions were applied: (1) an anterior drawer with an 89 N anterior tibial load, (2) simulated pivot-shift loading, (3) a 5 Nm internal rotational moment, and (4) a 5 Nm external rotational moment.

RESULTS

Under anterior tibial loading, anterior tibial translation increased, and graft force decreased significantly after ACL-R + 3 mm notchplasty and ACLR + 6 mm notchplasty compared to ACL-R alone at FE, 15° and 30° of knee flexion. There were no changes in either anterior tibial translation or graft force under simulated pivot-shift loading, internal rotational moment, or external rotational moment.

CONCLUSION

When added to anatomic ACL reconstruction, notchplasty increased anterior tibial translation and decreased graft forces during low knee flexion angles. There was no difference between a small and large notchplasty. The findings of this study are clinically relevant as the purpose of anatomic ACL reconstruction is to restore normal knee laxity, and while notchplasty may be helpful in avoiding graft impingement and improving visualization, removing even 3 mm of bone leads to biomechanical changes.

Greater Static Anterior Tibial Subluxation of the Lateral Compartment After an Acute Anterior Cruciate Ligament Injury Is Associated With an Increased Posterior Tibial Slope

BACKGROUND

Static anterior tibial subluxation of the lateral compartment after an anterior cruciate ligament (ACL) injury highlights an increased anterior position of the tibia relative to the femur. However, the precise cause of this phenomenon is not entirely clear. Recently, an increased posterior tibial slope (PTS) has been identified as an independent risk factor for noncontact ACL injuries.

HYPOTHESIS

An increased PTS is associated with an increased anterior position of the lateral compartment of the tibia relative to the femur after acute ACL injuries.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

From March 2016 to March 2017, a total of 154 patients with clinically diagnosed noncontact ACL injuries who underwent primary ACL reconstruction were retrospectively analyzed. Static anterior subluxation of the lateral compartment relative to the lateral femoral condyle was measured on preoperative magnetic resonance imaging. Among them, 23 patients (study group) who demonstrated ≥6-mm anterior subluxation of the lateral compartment were matched in a 1:1 fashion to 23 control participants (control group), who showed <6-mm anterior subluxation of the lateral compartment. The PTS was measured on routinely available preoperative weightbearing lateral knee radiographs. Predictors of increased (≥6 mm) static anterior subluxation of the lateral compartment, including body mass index (BMI), PTS, injuries to the anterolateral ligament (ALL), and concomitant lateral meniscal lesions, were assessed by multivariable conditional logistic regression analysis.

RESULTS

The mean PTS in the study group was 15.4°, which was significantly larger than that in the control group (8.8°) ( P < .001). In addition, an abnormal degree of PTS (≥10.0°) was determined to be an independent risk factor (odds ratio, 8.0 [95% CI, 2.7-29.2]; P < .001) associated with ≥6-mm anterior subluxation of the lateral compartment after acute ACL injuries. However, BMI, presence of concomitant lateral meniscal lesions, and presence of ALL ruptures were not.

CONCLUSION

An increased PTS was identified to be an independent anatomic risk factor of increased (≥6 mm) anterior subluxation of the lateral compartment in acute noncontact ACL injuries. For patients with obviously increased anterior tibial subluxation of the lateral compartment after ACL injuries, the PTS should be measured.

Effects of Notchplasty on Anterior Cruciate Ligament Reconstruction: A Systematic Review

Purpose  Notchplasty is a complementary surgical procedure often performed during anterior cruciate ligament reconstruction (ACLR) with the aim to widen the intercondylar notch and to avoid graft impingement. The aim of this review was to analyze the current literature evidence concerning the effects of notchplasty on clinical outcome after primary ACLR.

Methods  Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed, and MEDLINE were used to search English language studies, from January 1990 to July 2015, concerning the effects of the notchplasty on ACLR, using the following keywords: “ACL” OR “anterior cruciate ligament” OR “ACL reconstruction” OR “anterior cruciate ligament reconstruction” AND “notch” OR “notchplasty” OR “intercondylar notch”. Randomized and nonrandomized trials, case series, technical notes, biomechanical studies and radiological study were included.

Results  At the final screening 16 studies were included. Despite widely used, the usefulness of notchplasty during ACLR remains unclear. Some concerns emerged regarding potential harmful effects of notchplasty, mostly related to the knee biomechanics and postoperative blood loss. Notchplasty can be useful in the treatment of arthrofibrosis and in presence of bony spurs of the notch both in primary and revision surgery. However, the level of evidence of available literature is poor and there is a strong need for randomized controlled trials investigating the role of notchplasty on ACLR.

Conclusion  We suggest being aware of potential complications following notchplasty during ACLR before deciding to perform notchplasty in primary ACLR, reserving it for the surgical management of arthrofibrosis, treatment of notch osteophytosis and revision ACLR.

Level of Evidence  Level IV, systematic review of level II-IV studies.

Passive Anterior Tibial Subluxation in the Setting of Anterior Cruciate Ligament Injuries: A Comparative Analysis of Ligament-Deficient States

BACKGROUND

Static anterior tibial subluxation after an anterior cruciate ligament (ACL) injury highlights the abnormal relationship between the tibia and femur in patients with ACL insufficiency, although causal factors including injuries to secondary stabilizers or the time from injury to reconstruction have not been examined.

PURPOSE

To determine static relationships between the tibia and femur in patients with various states of ACL deficiency and to identify factors associated with anterior tibial subluxation.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Patients treated for ACL injuries were identified from an institutional registry and assigned to 1 of 4 cohorts: intact ACL, acute ACL disruption, chronic ACL disruption, and failed ACL reconstruction (ACLR). Anterior tibial subluxation of the medial and lateral compartments relative to the femoral condyles were measured on magnetic resonance imaging (MRI), and an MRI evaluation for meniscal tears, chondral defects, and injuries to the anterolateral ligament (ALL) was performed.

RESULTS

One hundred eighty-six ACL-insufficient knees met inclusion criteria, with 26 patients without an ACL injury utilized as a control group. In the lateral compartment, the mean anterior tibial subluxation measured 0.78 mm for the control group (n = 26), 2.81 mm for the acute ACL injury group (n = 74), 3.64 mm for the chronic ACL injury group (n = 40), and 4.91 mm for the failed ACLR group (n = 72). In the failed ACLR group, 37.5% of patients demonstrated lateral compartment anterior subluxation ≥6 mm, and 11.1% of this group had anterior subluxation of the lateral compartment ≥10 mm. Multivariate regression revealed that the presence of both medial and lateral chondral defects was associated with a mean 1.09-mm increase in subluxation of the medial compartment ( P = .013). The combination of medial and lateral meniscal tears was an independent predictor of increased lateral tibia subluxation by 1.611 mm ( P = .0022). Additionally, across all knee states, an injury to the ALL was associated with increased anterior tibial subluxation in both the medial compartment ( P = .0438) and lateral compartment ( P = .0046). In 29.4% of knees with ALL injuries, lateral tibial subluxation was ≥6 mm, but with multivariate regression analysis, an ALL injury was not an independent predictor of anterior subluxation of the lateral compartment.

CONCLUSION

Knees with failed ACLR are associated with more anterior tibial subluxation than those with primary ACL deficiency. Using previously reported thresholds of 6 to 10 mm of lateral compartment subluxation for a positive pivot shift, between 11.1% and 37.5% of knees with failed ACLR may be in a "resting pivoted position." In primary ACL-deficient knees, anterior tibial subluxation is associated with chondral injuries and meniscal tears but not injury chronicity.

Impingement following anterior cruciate ligament reconstruction: comparing the direct versus indirect femoral tunnel position

PURPOSE

During anterior cruciate ligament (ACL) reconstruction, authors have suggested inserting the femoral tunnel at the biomechanically relevant direct fibres, but this higher position can cause more impingement. Therefore, we aimed to assess ACL graft impingement at the femoral notch for ACL reconstruction at both the direct and indirect tunnel positions.

METHODS

A virtual model was created for twelve cadaveric knees with computed tomography scanning in which a virtual graft was placed at direct and indirect tunnel positions of the anteromedial bundle (AM), posterolateral bundle (PL) or centre of the both bundles (C). In these six tunnel positions, the volume (mm³) and mid-point location of impingement (°) were measured at different flexion angles.

RESULTS

Generally, more impingement was seen with the indirect position compared with the direct position although this was only significant at 90° of flexion for the AM position (97 ± 28 vs. 76 ± 20 mm³, respectively; p = 0.046). The direct tunnel position impinged higher at the notch, whereas the indirect position impinged more towards the lateral wall, but this was only significant at 90° of flexion for the AM (24 ± 5° vs. 34 ± 4°, respectively; p < 0.001) and C position (34 ± 5° vs. 42 ± 5°, respectively; p = 0.003).

CONCLUSION

In this cadaveric study, the direct tunnel position did not cause more impingement than the indirect tunnel position. Based on these results, graft impingement is not a limitation to reconstruct the femoral tunnel at the insertion of the biomechanically more relevant direct fibres.

Notchplasty for the Arthroscopic Treatment of Limited Knee Extension

Knee osteoarthritis may lead to narrowing of the intercondylar notch due to osteophyte formation, thereby causing changes in native knee biomechanics. The normal close contact between the condyles and the anterior cruciate ligament (ACL) during knee extension may be compromised due to narrowing of the notch and result in ACL damage, progression of knee osteoarthritis, and loss of knee extension. Outcomes after a notchplasty procedure are well reported for ACL reconstruction in young patients. However, there remains a lack of studies evaluating this procedure in the setting of knee osteoarthritis in patients with a symptomatic loss of knee extension. The purpose of this Technical Note is to present our preferred surgical technique for the treatment of loss of knee extension in the setting of knee osteoarthritis in conjunction with osteophyte formation in the intercondylar notch.

Anatomic anterior cruciate ligament reconstruction: reducing anterior tibial subluxation

PURPOSE

To measure and compare the amount of anterior tibial subluxation (ATS) after anatomic ACL reconstruction for both acute and chronic ACL-deficient patients.

METHODS

Fifty-two patients were clinically and radiographically evaluated after primary, unilateral, anatomic ACL reconstruction. Post-operative true lateral radiographs were obtained of both knees with the patient in supine position and knees in full passive extension with heels on a standardized bolster. ATS was measured on the radiographs by two independent and blinded observers. ATS was calculated as the side-to-side difference in tibial position relative to the femur. An independent t test was used to compare ATS between those undergoing anatomic reconstruction for an acute versus chronic ACL injury. Chronic ACL deficiency was defined as more than 12 weeks from injury to surgery.

RESULTS

Patients averaged 26.4 ± 11.5 years (mean ± SD) of age, 43.6 % were female, and 48.1 % suffered an injury of the left knee. There were 30 and 22 patients in the acute and chronic groups, respectively. The median duration from injury to reconstruction for the acute group was 5 versus 31 weeks for the chronic group. After anatomic ACL reconstruction, the mean ATS was 1.0 ± 2.1 mm. There was no statistical difference in ATS between the acute and chronic groups (1.2 ± 2.0 vs. 0.6 ± 2.3 mm, n.s.). Assessment of inter-tester reliability for radiographic evaluation of ATS revealed an excellent intraclass correlation coefficient of 0.894.

CONCLUSIONS

Anatomic ACL reconstruction reduces ATS with a mean difference of 1.0 mm from the healthy contralateral limb. This study did not find a statistical difference in ATS between patients after anatomic ACL reconstruction in the acute or chronic phase. These observations suggest that anatomic ACL reconstruction, performed in either the acute or the chronic phase, approaches the normal AP relationship of the tibiofemoral joint.

LEVEL OF EVIDENCE

IV.