Measures of lower limb alignment and knee joint load during walking were evaluated before and six months after medial opening wedge high tibial osteotomy (HTO) in ninety-five patients with knee medial compartment osteoarthritis (OA). Full-length standing radiographs were used to calculate the mechanical axis angle, and a gait analysis was performed to calculate the external adduction moment about the knee. Results indicated significant decreases in mechanical axis angle and peak adduction moment. These findings provide an indication of the early success of HTO in reducing the extent of lower limb malalignment and knee joint load during walking.

Medial opening wedge high tibial osteotomy (HTO) is intended to correct lower limb malalignment, resulting in decreased medial knee joint load and improved function. Due to the potential for the amount of alignment correction to change over time after surgery, frequent follow-up evaluations are encouraged.

To evaluate the early changes in lower limb alignment and medial knee joint load experienced during walking after medial opening wedge HTO.

Ninety-five patients (seventy-nine males, sixteen females; age range = 21–76 years; BMI range = 18.0–38.5) with knee joint OA affecting primarily the medial compartment underwent radiographic and gait analyses pre-surgically and six months following HTO. Full-length standing radiographs were obtained on both occasions and used to measure the static mechanical axis angle. Three-dimensional kinetic and kinematic data were also collected and combined to calculate the external knee joint adduction moment, an indirect measure of knee joint load. Paired t-tests indicated the mechanical axis angle (mean decrease = 8.32 degrees, 95% CI = 7.54,9.10) and peak external knee joint adduction moment (mean decrease = 1.61%BW*ht, 95% CI = 1.25,1.95) significantly decreased post-operatively (p< 0.001). These results indicate less varus angulation and reduced medial knee joint load following HTO.

These preliminary findings suggest that medial opening wedge HTO is an effective surgical treatment for improving alignment and reducing knee joint load.

Although these early results are promising, future research is required to determine the long-term success of this surgery in the treatment of knee OA.

Funding:

CIHR, NSERC, Arthrex Inc.

Purpose: To compare lateral closing to medial opening wedge HTO for a similar angle of correction with regard to change in proximal tibial bony anatomy and posterior cruciate ligament tibial attachment integrity following standard tibial arthroplasty resection.

Methods: Ten cadaveric lower limbs were randomized by side to receive a 12° lateral closing or 12.5mm medial opening wedge HTO. Anteroposterior, lateral and long leg AP radiographs were performed before and after each osteotomy. Pre and post osteotomy measurements of the coronal proximal tibial angle (PTA), sagittal tibial slope and anatomical femorotibial angle were completed and change in angles calculated. Prior to osteotomy, the tibial PCL attachment area was calculated. Post osteotomy, a standardized tibial arthroplasty resection was performed and the remaining percentage PCL attachment area recorded.

Results: Initial radiographs demonstrated little variation between matched pairs. Compared to the medial opening wedge group, the lateral closing wedge specimens demonstrated a statistically significant greater mean change in the PTA of 3.5° (95% C.I., 2.0 to 5.1°, p = 0.003) and an overall tendency for posterior tibial slope reduction with a mean change of −3.4 ± 4.9°. The average osteotomy angle in the medial opening wedge specimens was 11.9 ± 0.7°. Following tibial arthroplasty resection, there was a significant difference in the remaining PCL tibial attachment percentage area of 84.6 ±14.9 % for medial opening wedge and 50.8 ± 19.3 % for lateral closing wedge for a statistically significant mean difference of 33.8 % (95% C.I. 5.1 to 62.4, p = 0.031).

Conclusions: Despite similar correction angles of 12° for lateral closing and 11.9° for medial opening, the former specimens demonstrated a greater alteration in proximal tibial bony anatomy compared to the latter. In the lateral closing wedge group, the tendency to reduce posterior tibial slope and produce a greater than anticipated change in PTA had a significant effect on the integrity of the PCL’s tibial attachment following tibial arthroplasty resection.

Thirty-six patients with anterior cruciate ligament (ACL) insufficiency and varus malalignment were treated with combined ACL reconstruction and medial opening wedge high tibial osteotomy (HTO). Average follow-up was twenty-five months. All patients had improved ligamentous stability and twenty-five patients returned to full activities. Osteotomy union rate was 100%, mechanical axis angle was corrected from six degrees varus to neutral and the mechanical axis deviation was corrected from 2cm medial to 1cm lateral. We experienced four complications, including one deep infection. Combining ACL reconstruction and HTO simultaneously accomplishes a ligamentously stable knee with corrected alignment, allowing patients to return to activity.

To determine clinical outcome after combined ACL reconstruction and medial opening wedge high tibial osteotomy (HTO).

ACL reconstruction with medial opening HTO can be a beneficial procedure in properly selected patients presenting with complaints of both pain and instability. Correction of varus mal-alignment may provide protection for articular cartilage and improve joint stability.

Concomitant medial opening HTO performed at time of ACL reconstruction allows patients to return to activities after one procedure with a ligamentously stable knee, corrected alignment, and potential protection of articular cartilage.

Thirty-six patients who underwent ACL reconstruction along with medial opening HTO were retrospectively evaluated postoperatively at an average of twenty-five months.

Average age was thirty-seven years at time of surgery. All patients were recreationally active. Pre-operatively all patients had knee pain and instability, varus angulation, and twenty-two patients had previous knee surgery. Semitendinosus/gracilis grafts were used in all patients, and osteotomies were fixed with Puddu plates. Postoperatively patients had improved ligmentous stability with radiographic and clinical evidence of osteotomy healing, and all but nine patients have returned to full activities. We experienced four complications: one ACL failure, one case of anterior laxity with tibial tunnel widening, and two infections. On average, MAD was corrected from 22mm medial to 10mm lateral; mechanical axis angle was corrected from 6.4 degrees of varus to 0.2 degrees of valgus; tibial slope was increased from 9.1 degrees to 10.3 degrees, and patellar height ratio was decreased from 0.9 to 0.8.

The peak external knee adduction moment during walking gait has been proposed to be a clinically useful measure of dynamic knee joint load in patients with knee osteoarthritis. However, there is limited information about the reliability of this measure, or its ability to detect change. The test-retest reliability and sensitivity to change of peak knee adduction moments were evaluated in thirty patients with varus gonarthrosis. Indices of relative and absolute reliability were excellent (intra-class correlation coefficient = 0.85, standard error of measurement = 0.36 % BW*Ht), and the sensitivity to change following high tibial osteotomy was high (standardized response mean = 1.2).

To estimate the test-retest reliability, measurement error and sensitivity to change of the peak knee adduction moment during gait.

Thirty patients (44”11 yrs, 1.7”0.09 m, 87”20 kg, twenty males, ten females) with varus gonarthrosis underwent gait analyses on two pre-operative test occasions within one week, and on a third test occasion six months after medial opening wedge high tibial osteotomy. Three-dimensional kinematic and kinetic gait data were collected during self-paced walking and used to calculate the peak knee adduction moment.

An intraclass correlation coefficient of 0.85 (95%CI: 0.71, 0.93) indicated excellent relative reliability, and a standard error of measurement of 0.36 %BW*Ht (95%CI: 0.29, 0.49) indicated low measurement error. The peak knee adduction moment after surgery (1.66”0.72 %BW*Ht) was significantly (p< 0.001) lower than before surgery (2.58”0.72 %BW*Ht). A standardized response mean of 1.2 (95%CI: 0.77, 1.6) indicated the size of this change was large.

Based on 95% confidence levels, these results suggest the error in an individual’s peak knee adduction moment at one point in time is 0.70 % BW*Ht, the minimal detectable change in an individual’s peak adduction moment is 1.0 %BW*Ht, and it is sensitive to change following treatment.

The peak knee adduction moment during gait has appropriate reliability for use in studies evaluating the effect of treatments intended to decrease the load on the knee. When considering measurement error, the knee adduction moment is also appropriate for clinical use in evaluating change in individual patients.

Funding: CIHR, Arthrex Inc.

Introduction The goal of HTO is to re-align the mechanical axis to neutral or over corrected.

Methods I present a personal series of 22 opening wedge high tibial osteotomies in 20 patients with chronic posterior or posterolateral instability. Pre-operatively standing long leg views and a lateral view in extension are required to asses the mechanical axis and the posterior slope of the tibia. The osteotomy needs to be tailored to the pathology, remembering that increasing the posterior slope of the tibia worsens an ACL but improves a PCL deficit.

Results Sixty percent of the patients reported that knee stability was significantly better, 35% somewhat and 5% no better. All 20 patients reported that they would undergo the procedure again. Alignment was altered a mean of four degrees valgus and posterior tibial slope was increased by a mean of seven degrees.

Conclusions Simultaneous correction of knee mal-alignment and tibial slope by an opening wedge osteotomy can produce good functional and radiographic results.

In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.

Introduction: It has been proposed that tunnel widening in ACL reconstructions is due to excessive graft tunnel motion secondary to elastic fixation.

Aim: To determine whether techniques which fix the graft closer to the joint (interference screws), eliminate the bungy cord and are stiffer will decrease tunnel widening. The clinical significance of tunnel widening is examined.

Method: Two hundred and fifty nine patients were evaluated prospectively. Four fixation methods were evaluated. Sixty-nine were reconstructed using Endobuttons and staples (elastic fixation). Forty-eight were subjects reconstructed with a bone mulch screw and staples, 55 patients were reconstructed with metal interference screws and 87 with bioabsorbable interference screws. Patients underwent a clinical examination, IKDC, Cincinnati knee score and KT-1000 testing one year post-operatively. These factors were correlated with tunnel widening. Tunnel widening was determined using magnification adjusted AP and lateral radiographs using Scion Image software.

Results: Tunnel widening occurred with all the fixation methods. Mean tunnel area increased 122% for the Bioscrew, 89% for the metal interference screw, 76% for the bone mulch screw and 36% for the Endobutton (ANOVA p=< 0.0001). Tunnel widening did not correlate with increased laxity, poor IKDC or Cincinnati knee scores.

Conclusions: Tunnel widening occurred with both elastic and rigid fixation methods. Tunnel widening could not be avoided by fixing the graft closer to the joint or eliminating the ‘bungy cord’. Graft tunnel motion was not the sole cause of tunnel widening in ACL reconstruction. Tunnel widening did not correlate with poor outcome in the short term.