Cartilage regeneration is related to superior mid-term patient-reported outcomes after open-wedge high tibial osteotomy

PURPOSE

Medial open-wedge high tibial osteotomy (OWHTO) is related to cartilage improvement in the medial compartment. This study aimed to evaluate factors associated with cartilage improvement and patient-reported outcomes (PRO) after OWHTO. It was hypothesised that cartilage improvement is associated with favourable PRO.

METHODS

This retrospective study included 94 patients who underwent OWHTO. The mean follow-up period was 5 years. The weight-bearing line ratio (WBLR) was defined as the ratio of the distance from the medial tibial edge to the tibial insertion of the weight-bearing line and the tibial width. The International Cartilage Research Society grade evaluated the medial femoral condyle (MFC) and medial tibial plateau (MTP) at initial and second-look arthroscopy, and cartilage improvement after OWHTO was assessed. Postoperative knee injury and osteoarthritis outcome scores (KOOS) were compared between the groups with improved and non-improved cartilage. Additionally, factors related to cartilage improvement and postoperative KOOS scores were analysed.

RESULTS

Regarding the MFC, KOOS pain, symptoms, activities of daily living (ADL) and quality of life (QOL) were significantly higher in the cartilage-improved group than in the non-improved group (p = 0.012, 0.003, 0.001, 0.006), and cartilage improvement was significantly related to KOOS pain, ADL and QOL (p = 0.021, 0.039, 0.013). In addition, the postoperative WBLR was associated with cartilage improvement, with a cutoff value of 54.0% (p = 0.046). Regarding the MTP, KOOS ADL and QOL (p = 0.026, 0.022) were significantly higher in the cartilage-improved group than in the nonimproved group. Body mass index (BMI) was significantly related to the postoperative QOL (p = 0.018) and associated with cartilage improvement, with a cutoff value of 25.9 kg/m2 (p = 0.002).

CONCLUSION

A postoperative WBLR greater than 54.0% and a preoperative BMI below 25.9 kg/m2 were associated with cartilage improvement, positively impacting PRO after OWHTO.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Serial Quantitative Assessment of Load Redistribution After Medial Open-Wedge High Tibial Osteotomy

Background

The maximum standardized uptake value (SUV_max), as determined on combined single-photon emission computed tomography and conventional computed tomography (SPECT/CT), can be an indicator of biomechanical changes due to the load redistribution effect after medial open-wedge high tibial osteotomy (MOW-HTO).

Purpose/Hypothesis

The purposes of this study were to (1) analyze serial changes in the SUV_max in the medial, lateral, and patellofemoral compartments after MOW-HTO and (2) identify the contributing factors that affect changes in the SUV_max. The hypotheses were that (1) an elevated SUV_max in the medial compartment would be transferred to the lateral compartment because of the load redistribution effect and (2) there would be contributing factors that cause SUV_max changes.

Study Design

Case series; Level of evidence, 4.

Methods

Included were 67 knees that were treated with biplanar MOW-HTO between March 2019 and December 2020. SPECT/CT was performed immediately after surgery and at 3 months and 1 year postoperatively to determine the serial load redistribution effect of MOW-HTO. The Pearson correlation coefficient was used to evaluate the relationship between SUV_max and radiological parameters, and subgroup analyses were conducted to compare the SUV_max according to associated cartilage procedures and the weightbearing line ratio (WBLR).

Results

The SUV_max in the medial and lateral compartments increased at 3 months but decreased at 1 year postoperatively. The load redistribution effect was most prominent in the anterior zones of the femur (medial: P = .041; lateral: P = .012). In the patella, the SUV_max decreased in both the medial and the lateral zones at all follow-up times (P < .001 for all). The SUV_max in the anterolateral and posterolateral articular zones of the femur increased with a greater preoperative WBLR (r = 0.256, P = .039; and r = 0.261, P = .036, respectively). Patients who underwent an associated cartilage procedure had a significantly higher SUV_max in the anteromedial and posteromedial articular zones of both the femur and the tibia at 1 year postoperatively (P ≤ .002 for all).

Conclusion

After MOW-HTO, the unloading effect in the anteromedial articular zone of the femur was the most significant. A greater SUV_max in the lateral zones of the femur was observed in cases of overcorrection. The SUV_max in the medial zones was higher postoperatively in patients with associated cartilage procedures.

Changes in patellar baja progress until 3 months after medial open-wedge high tibial osteotomy

PURPOSE

The purpose of this study was to evaluate sequential patellar height changes as well as the factors leading to these changes after medial open-wedge high tibial osteotomy (MOWHTO).

METHODS

The study cohort constituted 37 knees from 36 patients who underwent MOWHTO for varus knee. The Caton-Deschamps index (CDI) for patellar height was measured preoperatively and at 2 weeks and 3, 6, and 12 months postoperatively. The factors related to sequential changes in patellar height were evaluated.

RESULTS

Significant differences were observed between preoperative CDI and postoperative CDI at all time points (p < .05). Two-week postoperative CDI and postoperative CDI at 3,6,12-months was also significantly different (p < .05). The only significant factor for the change in patellar height between preoperative CDI and postoperative CDI at 2-weeks and 12-months was the change in the Δ medial proximal tibial angle (ΔMPTA) (postoperative MPTA-preoperative MPTA). We could not identify the factor that affected the change in patellar height change from 2-weeks postoperatively.

CONCLUSION

The change in patellar height continued sequentially until at least 3 months postoperatively. ΔMPTA was associated with the change in patellar height at 2 weeks postoperatively compared with preoperatively; however, no factors associated with the change in patellar height from 2 weeks postoperatively to 3, 6, and 12-months postoperatively were identified.

Does Degeneration of the Patellofemoral Joint After Medial Open-Wedge High Tibial Osteotomy Affect Clinical Outcomes?

BACKGROUND

Although biomechanical and clinical studies have reported adverse effects on the patellofemoral joint after medial open-wedge high tibial osteotomy (MOWHTO), there is a paucity of literature that describes outcomes longer than midterm follow-up.

PURPOSE

We aimed to evaluate the mid- to long-term radiologic and clinical outcomes of the patellofemoral joint after MOWHTO and to assess whether radiologic deterioration of the patellofemoral joint affected clinical outcomes or survivorship after MOWHTO.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We retrospectively reviewed 170 knees that underwent MOWHTO and had a minimum 5-year follow-up. In radiologic evaluation, serial postoperative changes in the patellofemoral joint compared with the preoperative status were evaluated on the Merchant view according to the Kellgren-Lawrence grade. The American Knee Society (AKS) score, Knee injury and Osteoarthritis Outcome Score (KOOS), Kujala score, incidence of anterior knee pain, and survivorship were used to assess clinical outcomes. Using radiologic assessment of the patellofemoral joint, we divided the patients into a radiologic progression group and a radiologic nonprogression group to evaluate whether radiologic progression of patellofemoral arthritis affected long-term clinical outcomes and survivorship after MOWHTO.

RESULTS

The mean follow-up period was 96.3 months (range, 60-163 months). Arthritic progression of the patellofemoral joint on the Merchant view was observed in 44.9%, 56.3%, 66.0%, and 84.0% of the cases at 5, 7, 9, and 11 years, respectively. Clinical outcomes such as AKS scores and KOOS significantly improved after MOWHTO (P < .001) at the latest follow-up. The incidence of anterior knee pain was 5.3% (9/170 knees). One knee (0.6%) underwent conversion to TKA due to progressive medial osteoarthritis, so the survival rate was 99.4% at a mean follow-up of 96.3 months. Despite patellofemoral degeneration over time, there were no significant differences in clinical outcomes or survivorship between patients with and without radiologic progression at the latest follow-up.

CONCLUSION

Although degeneration of the patellofemoral joint was observed with time after MOWHTO, the related symptoms were minimal and arthritic changes in the patellofemoral joint did not affect the clinical outcomes or survivorship after MOWHTO over a mid- to long-term follow-up.

Serial Improvement of Medial Meniscus Extrusion Following Medial Open-Wedge High Tibial Osteotomy Does Not Correlate With Clinical Outcomes and Arthroscopic Articular Cartilage Improvement

PURPOSE

To assess serial change up to 2 years in medial meniscus extrusion (MME) following medial open-wedge high tibial osteotomy (MOWHTO) and to determine whether postoperative changes in MME correlated with clinical outcomes and arthroscopic articular cartilage status.

METHODS

This study included 26 patients from December 2016 to March 2018 who underwent MOWHTO for primary medial osteoarthritis with varus malalignment. Second-look arthroscopy with plate removal was performed at postoperative 2 years. MME was consecutively measured using coronal magnetic resonance imaging at preoperative and postoperative 3 months, 6 months, 1.5 years, and 2 years. We also assessed which preoperative parameters could reflect the postoperative changes in MME and evaluated whether postoperative clinical outcomes and arthroscopic articular cartilage improvement would be influenced by the MME changes.

RESULTS

Regarding the postoperative serial changes in MME values, significant improvement in MME was noted from postoperative 6 months (P = .003), and thereafter, mean MME was further improved with time until postoperative 2 years (P < .001). Regarding the correlation between preoperative parameters and MME changes, preoperative medial proximal tibial angle (MPTA) showed significant correlations in univariate and multivariate analysis (P = .004 and P = .004, respectively). Meanwhile, changes in MME were not correlated with postoperative clinical outcomes or arthroscopic articular cartilage improvement.

CONCLUSION

After MOWHTO, MME improved with time and was significantly correlated with preoperative MPTA. However, the changes in MME after MOWHTO did not reflect postoperative clinical and arthroscopic articular cartilage improvement.

LEVEL OF EVIDENCE

IV, case series.

Medial Meniscus Posterior Root Tear Does Not Affect the Outcome of Medial Open-Wedge High Tibial Osteotomy

BACKGROUND

This study aimed to verify whether the presence of medial meniscus posterior root tear (MMPRT) affects the clinical and radiographic outcomes of medial open-wedge high tibial osteotomy (MOWHTO) compared to the patients without MMPRT for over a midterm follow-up.

METHODS

One hundred fifty-six knees were retrospectively enrolled that underwent MOWHTO and second-look arthroscopy concomitantly with a minimum 5 years of follow-up. Seventy-four knees with MMPRT (MMPRT group) were identified. Eighty-two knees with intact MMPR were assigned to another group (MMPRI group). All knees with torn medial meniscus with or without MMPRT had an arthroscopic partial meniscectomy during the MOWHTO. Clinical evaluation included range of motion, American Knee Society scores, and Western Ontario and McMaster Universities Osteoarthritis Index scores. Radiologically, the Kellgren-Lawrence grade was assessed preoperatively and at the latest follow-up. Cartilage status was also compared through the 2-stage arthroscopy according to the International Cartilage Repair Society grading.

RESULTS

Average age at operation was 55.8 years (range 42-67), and the average follow-up period was 82.2 months (range 60-148). There were no significant differences in clinical outcomes between the groups. Postoperative changes in Kellgren-Lawrence grade and arthroscopic cartilage status showed no significant differences between the groups. Resected MMPR was remodeled in 41.9% (31/74) of the MMPRT group through the second-look arthroscopy.

CONCLUSION

MMPRT does not affect the clinical and radiologic outcomes of MOWHTO compared to those patients without MMPRT over a mid-term follow-up.

Effect of Medial Open-Wedge High Tibial Osteotomy on the Patellofemoral Joint According to Postoperative Realignment

BACKGROUND

No study has yet assessed the effect of medial open-wedge high tibial osteotomy (MOWHTO) on the patellofemoral joint according to postoperative alignment.

PURPOSE

To evaluate the effect of MOWHTO on the patellofemoral joint according to postoperative alignment by comparing the cartilage status before and after surgery and assessing the clinical and radiological outcomes.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 135 patients who underwent MOWHTO were retrospectively investigated. The patients were divided into 3 groups according to the postoperative weightbearing line ratio (WBLR): undercorrection (WBLR <58.3%, lowest quartile), acceptable correction (WBLR of 58.3%-66.3%, middle 2 quartiles), and overcorrection (WBLR >66.3%, highest quartile). The postoperative change in the cartilage status was assessed arthroscopically during implant removal at 2 years after MOWHTO. The clinical and radiological outcomes were evaluated at a mean follow-up of 52.1 months. A regression analysis was performed to identify the factors affecting the deterioration of the patellofemoral joint cartilage status. A receiver operating characteristic curve was employed to identify the cutoff point for the postoperative WBLR associated with the deterioration of the cartilage status in the patellofemoral joint.

RESULTS

Of all patients, progression of cartilage degeneration was noted in 39.3% for femoral trochlea and 23.7% for patella. The incidence of cartilage progression was significantly higher in the overcorrection group than in the undercorrection and acceptable correction groups (femoral trochlea: undercorrection group = 30.3%, acceptable correction group = 32.4%, and overcorrection group = 61.8% [P = .008]; patella: undercorrection group = 15.2%, acceptable correction group = 17.7%, and overcorrection group = 44.1% [P = .005]). The functional outcomes, including Lysholm knee score, Knee injury and Osteoarthritis Outcome Score (Pain, Symptoms, and Activities of Daily Living subscales), and Shelbourne and Trumper score, were significantly worse in the overcorrection group. The regression analysis showed that only the postoperative WBLR had a significant effect on cartilage deterioration. The cutoff point for the postoperative WBLR associated with progression of the International Cartilage Repair Society grade was 62.1% for the femoral trochlea (sensitivity = 61.5%, specificity = 62.7%, accuracy = 66.2%) and 62.2% for the patella (sensitivity = 59.4%, specificity = 60.2%, accuracy = 67.8%).

CONCLUSION

The patellofemoral joint was adversely affected by MOWHTO. Overcorrection causing excessive valgus alignment led to further progression of degenerative changes in the patellofemoral joint and inferior clinical outcomes. The postoperative WBLR can be used as a predictive factor for deterioration of the cartilage status in the patellofemoral joint after MOWHTO.