[Osteotomy around the knee vs. unicondylar knee replacement]

Factors to improve odds of success following medial opening-wedge high tibial osteotomy: a machine learning analysis

BACKGROUND

Although high tibial osteotomy (HTO) is an established treatment option for medial compartment osteoarthritis, predictive factors for HTO treatment success remain unclear. This study aimed to identify informative variables associated with HTO treatment success and to develop and internally validate machine learning algorithms to predict which patients will achieve HTO treatment success for medial compartmental osteoarthritis.

METHODS

This study retrospectively reviewed patients who underwent medial opening-wedge HTO (MOWHTO) at our center between March 2010 and December 2015. The primary outcomes were a lack of conversion to total knee arthroplasty (TKA) and achievement of a minimal clinically important difference of improvement in the Knee Injury and Osteoarthritis Outcome Score (KOOS) at a minimum of five years postoperatively. Recursive feature selection was used to identify the combination of variables from an initial pool of 25 features that optimized model performance. Five machine learning algorithms (XGBoost, multilayer perception, support vector machine, elastic-net penalized logistic regression, and random forest) were trained using five-fold cross-validation three times and applied to an independent test set of patients. The performance of the model was evaluated by the area under the receiver operating characteristic curve (AUC).

RESULTS

A total of 231 patients were included, and 200 patients (86.6%) achieved treatment success at the mean of 9 years of follow-up. A combination of seven variables optimized algorithm performance, and the following specific cutoffs increased the likelihood of MOWHTO treatment success: body mass index (BMI) ≤ 26.8 kg/m2, preoperative KOOS for pain ≤ 46.0, preoperative KOOS for quality of life ≤ 33.0, preoperative International Knee Documentation Committee score ≤ 42.0, preoperative Short-Form 36 questionnaire (SF-36) score > 42.25, three-month postoperative hip-knee-ankle angle > 1.0°, and three-month postoperative medial proximal tibial angle (MPTA) > 91.5° and ≤ 94.7°. The random forest model demonstrated the best performance (F1 score: 0.93; AUC: 0.81) and was transformed into an online application as an educational tool to demonstrate the capabilities of machine learning.

CONCLUSIONS

The random forest machine learning algorithm best predicted MOWHTO treatment success. Patients with a lower BMI, poor clinical status, slight valgus overcorrection, and postoperative MPTA < 94.7 more frequently achieved a greater likelihood of treatment success.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Management of medial femorotibial osteoarthritis: Epidemiology, and survival of unicompartmental knee arthroplasty versus valgus high tibial osteotomy in France. Study of 108,007 cases from the French National Hospitals Database

INTRODUCTION

Unicompartmental knee arthroplasty (UKA) and valgus high tibial osteotomy (HTO) are two options for isolated medial femorotibial osteoarthritis in genu varum. In the absence of registries for osteotomies and for arthroplasty in the knee, epidemiological data are hard to obtain in France. We therefore performed a retrospective study, with the aims of: 1) estimating UKA and HTO survival without revision by total knee arthroplasty (TKA), and 2) assessing risk factors for revision according to treatment group.

HYPOTHESIS

Medium-term survival is better with HTO than UKA in under-70-year-olds.

MATERIALS AND METHOD

All elderly patients undergoing HTO or UKA in the French National Hospitals Database for the period 2011-2020 were included: i.e., 108,007 patients; 43,537 HTO (29,330 male, 14,207 female; mean age 49.7 years, 95% CI 49.6-49.8) and 64,470 UKA (31,181 male, 33,289 female; mean age 60.5 years, 95% CI 60.5-60.6).

RESULTS

Survival free of revision by TKA was 75.8% (95% CI=75.2-76.4) for UKA and 80.6% (95% CI=80.0-81.3) for HTO (p<0.00001). In UKA, revision risk factors comprised: low annual center volume (<17 UKAs per year) (HR=1.50; 95% CI=1.41-1.59), obesity (HR=1.25; 95% CI=1.18-1.32), and age <60years, with maximum risk for 50-59years (HR=2.41; 95% CI=1.83-3.16 in 50-59 year-olds). In HTO, revision risk factors comprised: obesity (HR=1.42; 95% CI=1.31-1.53), rheumatoid arthritis (HR=2.75; 95% CI=1.37-5.51), joint chondrocalcinosis (HR=2.01; 95% CI=1.18-3.39), and age >60years (HR=8.81; 95% CI=7.23-19.73 in 60-69-year-olds). Male gender was a protective factor against revision in both groups: UKA, HR=0.75 (95% CI=0.72-0.79); HTO, HR=0.73 (95% CI=0.69-0.77). The number of UKAs increased over the years, matching the increase in arthroplasty in France, with a decrease in HTOs until 2019.

CONCLUSION

HTO showed better medium-term survival than UKA in under-70-year-olds in France. Even so, indications decreased in favor of UKA, although the respective risk factors differ. These findings suggest that conservative surgery still has a role, depending on osteoarthritis stage.

LEVEL OF EVIDENCE

III; retrospective comparative study.

Comparison of the clinical effects for different positions of the weight-bearing axis after high tibial osteotomy

PURPOSE

To analyze the clinical effects of different positions of the weight-bearing axis (WBA) after high tibial osteotomy (HTO).

METHODS

The clinical data of 90 patients who underwent HTO in the Department of Orthopedics at our hospital from June 2018 to June 2021 were retrospectively analyzed. Patients were divided into groups A and B (n = 45 per group) according to different post-HTO WBA positions of the affected side. WBAs in both groups were at 50-60% and 62-66% of the tibial plateau, from inside to outside, respectively. American Hospital for Special Surgery Knee Score (HSS), visual analog scale (VAS) score, femorotibial angle (FTA), and medial proximal tibial angle (MPTA) were recorded and analyzed.

RESULTS

All patients were followed up with for 12 months. HSS scores increased gradually and VAS scores decreased gradually in both groups preoperatively, and at 3 months, 6 months, and 1 year postoperatively (P < 0.05). Compared to group A, group B had better HHS scores at 6 months and 1 year postoperatively (P < 0.05). There was no significant between-group difference in VAS scores at all aforementioned timepoints (P > 0.05). Postoperative MPTA and FTA were 89.56° ± 2.18° and 177.11° ± 2.63° in group A, and 89.07° ± 1.98° and 177.07° ± 2.36° in group B, respectively, with no significant between-group difference (P > 0.05).

CONCLUSION

Patients with post-HTO WBA ranges of 50-60% and 62-66% achieved knee joint function improvement and pain relief. Half a year later, those with a WBA range of 62-66% had better knee joint function scores. However, a comparison of long-term effects warrants further investigation.

Survivorship of high tibial osteotomy in the treatment of osteoarthritis of the knee: a retrospective cohort study with fourteen years' follow-up

PURPOSE

This study was to evaluate the survivorship of HTO for the treatment of medial compartment osteoarthritis (OA) in young and active patients from two teaching hospitals in a single city.

METHODS

This is a retrospective cohort multicenter study looking at HTO for treatment of medial compartment OA. We analyzed a case series of HTO's performed by four surgeons in two centres over a 14-year period. Failure was defined as conversion to total knee replacement (TKR). All cases where additional procedures for instability of the knee were performed at the time of the index surgery were excluded. Time to failure was recorded, and a Kaplan-Meir (KM) analysis was performed to evaluate survivorship. Univariate binary regression analysis was undertaken to identify associations between risk factors and failure.

RESULTS

A total of 96 patients were included in the study with a median age was 45 years. The survivorship at five years post-op was 90.3%, and at ten years post-op, it was 82%. Patients that were 14 years after surgery had a survivorship of 65%. Also, 18.8% of patients required the removal of their metalwork. The overall complication rate was 6.3%. The univariate regression analysis showed that higher age (p = 0.02) and larger corrections requiring the use of bone graft increased the risk of failure (p = 0.02). There was no statistically significant correlation between laterality, gender, complication rate, and pre-operative alignment to survivorship.

CONCLUSION

This is one of the largest reported case series of HTO's with comparable survivorship at five and ten year follow-up compared to the reported literature. There was an association found between increasing age and larger corrections requiring bone graft at index procedure to increasing failure rate.

Osteotomy Around the Knee: The Surgical Treatment of Osteoarthritis

Osteoarthritis causes joint pain and functional disorder, of which knee osteoarthritis is the most common. Nowadays, clinically effective treatments mainly include conservative treatment, arthroplasty, and osteotomy. However, conservative treatment only offers symptomatic relief and arthroplasty is limited to the patients with a moderate to severe degree of osteoarthritis. For relatively young patients who require greater knee preservation, a surgical treatment with low operation trauma and revision rate is needed. Osteotomy around the knee, based on the notion of “knee preservation,” has been chosen as an alternative surgical treatment. Cutting and realigning the bones corrects the mechanical line of lower limb force bearing. As such, osteotomy around the knee retains normal anatomical structure and obtains good functional recovery of the knee joint. The techniques of osteotomy around the knee includes anti‐varus deformity and anti‐valgus deformity osteotomy, aiming to reallocate the force bearing in the compartment of the knee joint. By choosing the surgical section of the lower limbs, the osteotomy around the knee can achieve the correction of mechanical axis, such as the high tibial osteotomy (HTO), proximal fibular osteotomy (PFO), and distal femur osteotomy (DFO). Numerous modified techniques have been developed to meet the demands of patients based on traditional methods. These modified osteotomy have their own advantages and indications. This paper aims to guide clinical treatment by reviewing different types of osteotomies, and their effects, that have been studied and applied widely in clinical practices.

Complications, Additional Surgery, and Joint Survival Analysis After Medial Open-Wedge High Tibial Osteotomy

The reported incidence of complications following medial open-wedge high tibial osteotomy (MOWHTO) varies. The authors sought to assess the complications, additional surgeries, and joint survival following MOWHTO in patients with isolated medial compartment arthrosis during a mean follow-up of 10 years. This retrospective study involved patients implanted with spacer plates, angle adjustable plates, or inverse L-type plates with wedges between 2000 and 2010. A total of 504 knees from 441 patients were examined. Mean age of the study population was 52.6±7.0 years, with 56 (11.1%) knees from men and 448 (88.9%) from women. The 10-year Kaplan-Meier joint survival rate was 94.8%. Overall complication rate for MOWHTO was 63.7%, with complications in 20.3% of treated knees requiring additional surgery. In this population, although the overall complication rate and the need for additional surgery were high, the need for additional surgery resulting from serious complications was low (2.6%). The high joint survival rate and low rate of additional surgery for serious complications indicate that MOWHTO can be safely applied in patients with isolated medial gonarthrosis. [Orthopedics. 2020;43(5):303-314.].

The learning curve of patient-specific unikondylar arthroplasty may be advantageous to off-the-shelf implants: A preliminary study

Introduction

Introducing a new arthroplasty system into clinical routine is challenging and could have an effect on early results. Since UKA are known to have failure mechanisms related to technical factors, reliable results and easy adoption are ideal. The question remains whether there are differences in objective procedure parameters in the early learning curve of different UKA systems.

Methods

two different UKA implants (Biomet Oxford[BO] followed by Conformis iuni[CI]) were introduced consecutively into clinical routine. We retrospectively analyzed the first 20 cases of each implant for one arthroplasty surgeon regarding operating time, correction of the mechanical axis, learning curve parameters, and revision rate of implants for 1.5 years postoperatively.

Results

Operating time (BO:98.3 ± 26.3min, CI:83.85 ± 21.8min (p < 0.078)), and tourniquet time differed in favor of the CI implant (BO:97.5 ± 29.5min; CI:73.5 ± 33.2 min; p < 0.017)). Mechanical alignment was restored in boths (preop:BO:mean 2.9°varus, CI:2.7°varus, postop:BOmean1.3°varus, CI:1°varus), while one BO patient and two CI patients were overcorrected. Operating time decreased from the first five implants to implants 16-20 for CI (95.2 ± 18.5min to 69 ± 21.5min, p < 0.076) and BO (130.6 ± 27.6min to 78 ± 17.3min, p < 0.009). Within 18 months of follow-up, 2 BO and 1 CI implants were revised.

Conclusion

The introduction of an UKA implant was associated with longer surgery in both implants. Procedure time seems to differ between implants, while a learning curve was observed regarding instrumentation. CI implants seem to be reliable and adaptable in a medium-volume practice. The early results of this retrospective single-surgeon study were in favor of the individualized implant. Certainly, further studies encompassing larger cohorts with various implants are needed.

The influence of tibial slope on the graft in combined high tibial osteotomy and anterior cruciate ligament reconstruction

BACKGROUND

Young patients with severe medial osteoarthritis, varus malalignment and insufficiency of the anterior cruciate ligament (ACL) are difficult to treat. The tibial slope has gained attention with regard to osteotomies and ligamentous instability. The purpose was to evaluate the outcome of combined high tibial osteotomy (HTO), ACL reconstruction and chondral resurfacing (CR, abrasion plus microfracture), and to analyse graft failure rates with regard to the tibial slope.

METHODS

Fifty cases (48.9 ± 5.4 years) of combined HTO, ACLR and CR were retrospectively analysed with regard to survival, functional outcome (subjective International Knee Documentation Committee (IKDC) examination form) and subjective satisfaction. The tibial slope was determined on lateral radiographs and analysed with regard to its influence on graft functionality at the time of hardware removal.

RESULTS

Follow-up rate was 100% after 5.6 ± 1.6 years. No arthroplasties were performed. Subjective IKDC score was 70 ± 18, and 94% were satisfied with the result. The graft was intact in 39 cases (78%), and non-functional in 11 cases (22%). No significant changes were present in pre- and postoperative tibial slope (P = 0.811). Graft insufficiency was strongly dependent on tibial slope, with a failure rate of seven percent in cases of postoperative tibial slope <7.5°, 24% in cases of 7.5-12.5°, and 36% in cases of >12.5°.

CONCLUSION

Combined HTO, ACLR and CR is an effective treatment in these cases. The graft failure rate increases with an increase in tibial slope, in particular when exceeding 12.5°.

LEVEL OF EVIDENCE

Case series, Level 4.

Ten-Year Results of Medial Open-Wedge High Tibial Osteotomy and Chondral Resurfacing in Severe Medial Osteoarthritis and Varus Malalignment

BACKGROUND

High tibial osteotomy (HTO) is a widely used treatment option for medial osteoarthritis and varus malalignment, especially in young patients with early osteoarthritis. Limited outcome data are available for this procedure in severe osteoarthritis, and no long-term data are available using newer implants.

PURPOSE

To determine survivorship and functional results of medial open-wedge HTO combined with a chondral resurfacing (CR) procedure (abrasion plus microfracture) in severe medial osteoarthritis (Kellgren-Lawrence grade 3 and 4) and varus malalignment. Furthermore, factors that potentially influence the outcome were analyzed.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

From September 2005 to December 2008, all cases of HTO (fixation with an angular-stable internal fixator) combined with CR were prospectively surveyed with regard to survival (Kaplan-Meier-method, not requiring arthroplasty) and functional outcome (subjective International Knee Documentation Committee [IKDC] score). Cartilage regeneration at the time of hardware removal, tibial bone varus angle (TBVA), pre- and postoperative mechanical medial proximal tibial angle (MPTA), and postoperative alignment were analyzed with regard to the result.

RESULTS

Seventy-nine knees were included (73 patients; mean age 50.9 ± 7.6 years). The follow-up rate was 90% at 10.0 ± 1.2 years (range, 8.3-12.1 years). Pre- and postoperative mechanical tibiofemoral axis were 9.6° ± 3.0° of varus and 0.6° ± 2.7° of valgus, respectively. Survival rate was 81.7% (95% CI, 72.5%-90.9%) at 10 years. Subjective IKDC score significantly improved from 44 ± 11 preoperatively to 70 ± 13 at one, 66 ± 15 at three, 66 ± 15 at five, and 65 ± 17 at ten years ( P < .001 at any point of follow-up). Poor cartilage regeneration and low preoperative IKDC score (<40) were associated with decreased survival. High preoperative TBVA was associated with better and an overcorrected MPTA (>95°) with inferior functional outcome at final follow-up, respectively.

CONCLUSION

Even in cases of severe medial osteoarthritis and varus malalignment, HTO in combination with a CR procedure is a good to excellent treatment option. The role of the CR procedure remains unclear. Although good results are obtained with overcorrected MPTA, long-term functional outcome is inferior.

Load distribution in early osteoarthritis

Total knee replacement is an accepted standard of care for the treatment of advanced knee osteoarthritis with good results in the vast majority of older patients. The use in younger and more active populations, however, remains controversial due to concerns over activity restrictions, implant survival, and patient satisfaction with the procedure. It is in these younger patient populations that alternatives to arthroplasty are increasingly being explored. Historically, osteotomy was utilized to address unicompartmental pain from degeneration and overload, for example, after meniscectomy. Utilization rates of osteotomy have fallen in recent years due to the increasing popularity of partial and total knee arthroplasty. This article explores the indications and outcomes of traditional unloading osteotomy, as well as newer options that are less invasive and offer faster return to function.

Large animal models in experimental knee sports surgery: focus on clinical translation

Large animal models play a crucial role in sports surgery of the knee, as they are critical for the exploration of new experimental strategies and the clinical translation of novel techniques. The purpose of this contribution is to provide critical aspects of relevant animal models in this field, with a focus on paediatric anterior cruciate ligament (ACL) reconstruction, high tibial osteotomy, and articular cartilage repair. Although there is no single large animal model strictly replicating the human knee joint, the sheep stifle joint shares strong similarities. Studies in large animal models of paediatric ACL reconstruction identified specific risk factors associated with the different surgical techniques. The sheep model of high tibial osteotomy is a powerful new tool to advance the understanding of the effect of axial alignment on the lower extremity on specific issues of the knee joint. Large animal models of both focal chondral and osteochondral defects and of osteoarthritis have brought new findings about the mechanisms of cartilage repair and treatment options. The clinical application of a magnetic device for targeted cell delivery serves as a suitable example of how data from such animal models are directly translated into in clinical cartilage repair. As novel insights from studies in these translational models will advance the basic science, close cooperation in this important field of clinical translation will improve current reconstructive surgical options and open novel avenues for regenerative therapies of musculoskeletal disorders.