Distal femoral osteotomy versus lateral unicompartmental arthroplasty for isolated lateral tibiofemoral osteoarthritis with intra-articular and extra-articular deformity: a propensity score-matched analysis

Perfect Indications and How to Avoid Complications in Lateral Unicompartmental Knee Arthroplasty

Lateral unicompartmental knee arthroplasty (LUKA) is a favorable alternative to distal femoral osteotomy and total knee arthroplasty in patients with isolated lateral compartment knee osteoarthritis; however, it only accounts for less than 1% of the total number of knee replacements documented in national joint registries. The anatomy and biomechanics of the lateral knee compartment differ from the medial side, with a greater intrinsic laxity of the lateral collateral ligament complex compared to medial structures. Indications and surgical techniques must be tailored to each unicompartmental replacement to optimize outcomes and mitigate complications. This article will discuss the clinical indications, preoperative evaluation and workup, surgical technique, and outcomes for LUKA.

Artificial intelligence-based assessment of leg axis parameters shows excellent agreement with human raters: A systematic review and meta-analysis

PURPOSE

The aim of this study was to conduct a systematic review and meta-analysis on the reliability and applicability of artificial intelligence (AI)-based analysis of leg axis parameters. We hypothesized that AI-based leg axis measurements would be less time-consuming and as accurate as those performed by human raters.

METHODS

The study protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO). PubMed, Epistemonikos, and Web of Science were searched up to 24 February 2024, using a BOOLEAN search strategy. Titles and abstracts of identified records were screened through a stepwise process. Data extraction and quality assessment of the included papers were followed by a frequentist meta-analysis employing a common effect/random effects model with inverse variance and the Sidik-Jonkman heterogeneity estimator.

RESULTS

A total of 13 studies encompassing 3192 patients were included in this meta-analysis. All studies compared AI-based leg axis measurements on long-leg radiographs (LLR) with those performed by human raters. The parameters hip knee ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), and joint-line convergence angle (JLCA) showed excellent agreement between AI and human raters. The AI system was approximately 3 min faster in reading standing long-leg anteroposterior radiographs (LLRs) compared with human raters.

CONCLUSION

AI-based assessment of leg axis parameters is an efficient, accurate, and time-saving procedure. The quality of AI-based assessment of the investigated parameters does not appear to be affected by the presence of implants or pathological conditions.

LEVEL OF EVIDENCE

Level I.

Comparison of Trends and Complications of Unicompartmental Knee Arthroplasty Versus Periarticular Knee Osteotomy Among ABOS Part II Oral Examination Candidates

Background

While unicompartmental knee arthroplasty (UKA) and osteotomy procedures are commonly used to treat knee osteoarthritis, the differences in complication profiles between procedures are still poorly understood.

Purpose/Hypothesis

The purpose of this study was to assess the trends and complication rates of UKA and periarticular knee osteotomy for knee osteoarthritis among newly trained surgeons by using the American Board of Orthopaedic Surgery (ABOS) Part II Oral Examination Case List database. It was hypothesized that more adult reconstruction fellowship-trained surgeons would perform UKA, while more sports medicine fellowship-trained surgeons would perform osteotomy, and that both procedures would have low rates of complications.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

The ABOS database was queried for patients who underwent UKA, high tibial osteotomy, and distal femoral osteotomy procedures in examination years 2011 to 2021. Patient characteristics, surgeon fellowship training history, surgeon-reported postoperative complications, and readmission and reoperation rates were recorded. Comparisons between the UKA and osteotomy groups were performed using independent t tests and chi-square tests.

Results

There were 2524 patients in the UKA group and 270 patients in the osteotomy group. The majority of newly trained surgeons performing UKA (70.5%) had fellowship training in adult reconstruction, while the majority of those performing osteotomy (57.8%) had fellowship training in sports medicine (P < .001). The incidence of UKA and osteotomy increased during the study period (18.8 UKAs and 1.8 osteotomies performed per 10,000 cases in 2011 vs 39.5 UKAs and 4.2 osteotomies performed per 10,000 cases in 2021). Rates were significantly higher for osteotomy compared with UKA regarding anesthetic complications (2.2% vs 0.6%; P = .015), surgical complications (23.7% vs 7.3%; P < .001), reoperation (5.2% vs 1.9%; P = .002), and infection (6.7% vs 1.4%; P < .001). There were no significant differences in rates of medical complication, readmission, deep vein thrombosis, pulmonary embolism, or stiffness/arthrofibrosis.

Conclusion

Among newly trained surgeons taking the ABOS Part II Oral Examination, the incidence of UKA and periarticular knee osteotomy increased over the past decade. Compared with UKA, complication rates were higher after osteotomy, with an overall surgical complication rate of 23.7%.

Similar Midterm Outcomes of Total Knee Arthroplasties with Anterior and Posterior Tibial Slopes Performed on Paired Knees at a Minimum Follow-up of 5 Years

A small posterior tibial slope (PTS) is generally recommended in posterior stabilized (PS) total knee arthroplasty (TKA). An unwanted anterior tibial slope (ATS), which can affect postoperative results, may be created in PS TKA because of the inaccuracy of surgical instruments and techniques, as well as high interpatient variability. We compared midterm clinical and radiographic results of PS TKAs with ATS and PTS performed on paired knees using the same prosthesis. One-hundred-twenty-four patients who underwent TKAs with ATS and PTS on paired knees using ATTUNE posterior-stabilized prostheses were retrospectively reviewed after a minimum follow-up period of 5 years. The mean follow-up period was 5.4 years. The Knee Society Knee and Function scores, Western Ontario and McMaster Universities Osteoarthritis Index, Feller and Kujalar scores, and range of motion (ROM) were evaluated. The preferred TKA out of ATS and PTS was also investigated. The hip-knee-ankle angle, component positions, tibial slope, posterior femoral offset, Insall-Salvati ratio, and knee sagittal angle were measured by radiography. There were no significant differences in the clinical results, including ROM, between TKAs with ATS and PTS preoperatively and at the last follow-up. Regarding patient preference, 58 patients (46.8%) were satisfied with bilateral knees, 30 (24.2%) preferred knees with ATS, and 36 (29%) preferred knees with PTS. There was no significant difference in the rate of preference between TKAs with ATS and PTS (p = 0.539). Except for the postoperative tibial slope (-1.8 vs. 2.5 degrees, p < 0.001), there were also no significant differences in the radiographic results, including the knee sagittal angle, preoperatively and at the last follow-up. The midterm outcomes were similar between PS TKAs with ATS and PTS performed on paired knees at a minimum of 5 years of follow-up. Nonsevere ATS did not affect midterm outcomes in PS TKA with proper soft tissue balancing and the current prosthesis of improved design. However, a long-term follow-up study is required to confirm the safety of nonsevere ATS in PS TKA. LEVEL OF EVIDENCE::  III.

Effect of mediolateral gap difference on postoperative outcomes in navigation-assisted total knee arthroplasty using an ultracongruent insert and the medial stabilising technique

PURPOSE

This study was aimed to compare the clinical, functional, and radiographic outcomes between symmetric and asymmetric extension and mediolateral gap balance after navigation-assisted (NA) total knee arthroplasty (TKA) using ultracongruent (UC) insets and the medial stabilising technique (MST).

METHODS

In all, 363 knees of 275 patients who underwent mechanical alignment-target NA TKA with MST between January 2015 and December 2017 were analysed. Patients were divided into balanced (extension mediolateral gap difference ≤ 2 mm) and tight medial (difference ≥ 3 mm) groups. Pre- and postoperative clinical, functional (range of motion, Western Ontario and McMaster University Osteoarthritis [WOMAC] index, Knee Society Knee Score [KSKS], and Knee Society Function Score [KSFS]) and radiographic (hip-knee-ankle [HKA] angle, femoral condylar offset, extension angle [a minus indicates hyperextension], and joint line distance) outcomes were compared between the groups. Student's t- or Chi-squared test was used to compare the outcomes.

RESULTS

Among the 363 knees analysed, 279 (77%) were assigned to the balanced group and 84 (23%) to the tight medial group. The preoperative HKA angle was significantly greater in the tight medial group than in the balanced group (9.7° ± 4.1° vs 14.3° ± 4.7°, P < 0.001). The postoperative WOMAC index, KSKS, and KSFS were similar between the groups. The change in the joint line distance was not significantly different (1.5 ± 3.7 vs 2.0 ± 3.3; n.s).

CONCLUSION

The clinical, functional, and radiographic outcomes, including joint line distance, were comparable between the tight medial and balanced group after mechanical alignment-targeted UC TKA with MST.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

In closed wedge distal femur osteotomies for correction of valgus malalignment overcorrection of mLDFA should be avoided

PURPOSE

The purpose of the study was to investigate the influence of the mLDFA (mechanical lateral distal femur angle) as a parameter in varus realignment osteotomies for valgus deformities of the knee. We hypothesized that joint line obliquity with mLDFA > 90° after distal femur osteotomy (DFO) is associated with inferior clinical outcome.

METHODS

In a retrospective study, a total of 52 patients with isolated femoral valgus deformities were included in the study. The mean postoperative follow-up was 70.5 (SD 33.3) months (standard deviation SD±33.3). In all patients, a distal femur osteotomy was performed. A clinical examination and survey of questionnaires was conducted with the HSS (Hospital for Special Surgery), LG (Lysholm-Gilquist), and KOOS (Knee Injury and Osteoarthritis Outcome Score) scores. Several radiological parameters were assessed on long-standing x-rays: mechanical tibio-femoral angle (mTFA), mLDFA, mechanical medial proximal tibia angle (mMPTA), joint-line convergence angle (JLCA). The t test was used for normally distributed data. The Mann-Whitney U test was performed in non-normally distributed data.

RESULTS

The mLDFA was 84.9° (SD±2.3) preop and changed to 91.9° (SD±3, 22.9) postop. The mTFA (mechanical tibio-femoral angle) was 5.2° (SD±2.9°) preop and - 1.8° (SD±2.9) postop demonstrating a difference of 6.7°. For analysis, the data was divided into two groups based on postop mLDFA. Group 1: mLDFA ≤ 90°; Group 2: > 90°. Postoperatively, a mean mLDFA of 88.6° (SD±1.4°) was measured in group 1 and 93.9° (SD±2.1) in group 2. The change in mLDFA was 4.7° (SD±1.6) in group 1 and 8.4° (SD±2.8) in group 2. Preoperatively, the mTFA was 4.8° (SD±1.9) in group 1 and 5.5° (SD±3.3) in group 2. Postoperatively, the mTFA decreased in group 1 by 4.8° (SD±2.3) to - 0.1° (SD±2.1). In group 2, the mTFA decreased by 8.2° (SD±3.8) to - 2.8° (SD±2.9). Regarding the HSS, group 1 showed a 10.4 points better score than group 2 (p<0.01). Also, regarding the Lysholm, a significant difference of 16.9 points was found (p<0.01).

CONCLUSION

Correction of valgus knees using closed wedge DFO leads to good clinical results. A postoperative mLDFA of 85-90° results in superior clinical outcome compared to mLDFA > 90°. Joint-line obliquity should be avoided using double level osteotomy, if needed.

LEVEL OF EVIDENCE

III.

Long-Term Survival and Predictors of Failure of Opening Wedge High Tibial Osteotomy

OBJECTIVE

High tibial valgus osteotomy (HTO) is a widely accepted procedure indicated for varus knee with symptomatic osteoarthritis of the medial compartment. However, there is a lack of studies evaluating long term results of this procedure. The primary aim of this study was to evaluate the long-term survival of opening wedge high tibial osteotomy (HTO) for isolated osteoarthritis in the medial compartment of the knee. The secondary objective was to identify independent predictors of conversion to total knee arthroplasty (TKA).

METHODS

This is a long term retrospective study of 296 cases of open wedge HTOs performed at a single center (level of evidence IV) between January 2005 and August 2015. Opening wedge medial HTO was always performed after diagnostic arthroscopy. Eighty-three percent of the population (233 patients, 247 procedures) was followed up at a mean 11.6 years (6-17) by telephone interview, to evaluate the possible conversion to TKA. Mean age at the index operation was 42.8 years (range 15-70) and most patients were male (70%). Associated procedures (e.g., platelet rich plasma supplementation, microfractures, meniscectomy, etc.) were carried out at the time of the HTO in 80 (32%) cases. Survival of HTO and its association with age, sex, body mass index, smoking habit, preoperative severity of varus deformity, cartilage status at surgery, and associated procedures were evaluated. Kaplan-Meier and Cox regression analyses were performed.

RESULTS

Thirty-three of the 247 HTOs (13.4%) were converted to knee replacement, with 86.6% of the original procedures surviving at a mean 12-year follow-up. Kaplan-Meier survival estimates at 17 years for HTO were 75.5% (95% confidence interval [CI] 66.7-84.3). There was significant difference (P < 0.001) in the 17-year survival rate between obese (55.5%; 95% CI 35.3-75.6) and non-obese (79.7%; 95% CI 70.1-89.2) patients. The determinants of conversion to knee arthroplasty detected at multivariate Cox regression analysis were body mass index, severity of cartilage degeneration in the medial compartment (Outerbridge grade), and age.

CONCLUSION

The long-term survival of open wedge HTO for osteoarthritis in the medial compartment of the knee is satisfactory. The risk of conversion to TKA is significantly increased in obese patients. Advanced age and severity of pre-existing cartilage damage may also contribute to the risk of conversion to TKA.

Effects of Severe Varus Deformity on Soft Tissue Balancing in Total Knee Arthroplasty

This study aimed to establish the effect of severe varus deformity on soft tissue balance in total knee arthroplasty (TKA), which is not yet well established. We retrospectively enrolled 205 patients (270 knees) who underwent primary TKA using the measured resection technique. Four intraoperatively measured TKA gaps and gap differences were compared between the severe varus deformity group (Hip-knee-ankle [HKA] varus angle ≥ 10°) and the mild varus deformity group (HKA varus angle < 10°). Pearson’s correlation analysis and multiple linear regression analysis were used to investigate the factors affecting flexion and extension gap differences (FGD and EGD). A receiver operating characteristic curve was applied to assess the cut-off value of the HKA varus angle to discriminate the rectangular gap. The FGD (1.42 ± 1.35 mm vs. 1.05 ± 1.16 mm, p = 0.019) and the EGD (1.45 ± 1.32 mm vs. 0.97 ± 1.53 mm, p = 0.006) were significantly larger in severe varus deformity group than in mild varus deformity group. The HKA varus angle was positively correlated with both FGD (r = 0.264, p < 0.001) and EGD (r = 0.319, p < 0.001) and was an influencing factor for FGD (β = 0.232, p = 0.040) and EGD (β = 0.229, p = 0.037). A preoperative HKA angle of 12.4° was selected as the cutoff value to discriminate between rectangular and trapezoidal gaps. Thus, the severity of varus deformity (HKA varus angle) was found to be a significant factor affecting the mediolateral gap difference in TKA. When performing TKA in a knee with an HKA varus angle ≥ 12.4°, a trapezoidal gap is more likely to be expected. Level of evidence III, case−control study.

Fast-track surgery and telerehabilitation protocol in unicompartmental knee arthroplasty leads to superior outcomes when compared with the standard protocol: a propensity-matched pilot study

BACKGROUND

Several strategies have been devised to reduce the length of stay after orthopedic surgery. Telerehabilitation has proved effective in functional outcomes after orthopedic procedures and is appreciated by patients. There is limited information on fast-track surgery and telerehabilitation protocols for unicompartmental knee arthroplasty (UKA). The purpose of this pilot study was to report and compare functional outcomes and satisfaction levels during first 12 months of recovery in patients who underwent UKA according to a fast-track and telerehabilitation protocol (G1) or standard surgery and rehabilitation program (G2).

METHODS

Data were retrospectively collected and reviewed for all elective UKAs from January 2018 to November 2019. A total of seven patients undergoing UKA according to the fast-track and telerehabilitation protocol were propensity score matched (1:3 ratio) to 21 patients undergoing standard surgery and rehabilitation. Patients were matched for age, sex, body mass index (BMI), and laterality. The Western Ontario and McMaster University (WOMAC) osteoarthritis index and range of motion (ROM) were collected pre- and postoperatively in both groups for 12 months. In addition, patient' satisfaction was collected at 40 days.

RESULTS

The G1 group demonstrated significantly better outcomes in WOMAC index scores at 2, 15, and 40 days (p < 0.001, p < 0.001, p < 0.020, respectively) and a significantly greater knee ROM after surgery and at 2, 15, 40, and 12 months (p < 0.001, p < 0.001, p = 0.014, p < 0.001, p = 0.003, respectively). No patients in either group had postoperative complications. One patient was not completely satisfied in the G2, while no one in G1 reported not being completely satisfied (p = 1.000).

CONCLUSIONS

This fast-track and telerehabilitation protocol after UKA can potentially be applied to patients as it is safe and effective. At 12-months follow-up, both groups reported favorable outcomes after UKA. However, the G1 score was better regarding WOMAC and ROM when compared with the propensity score-matched G2 program. A larger study is warranted to explore the role of fast-track and telerehabilitation in clinical and functional outcomes of UKA.

Predictive Factors for Lateral Hinge Fracture in Medial Closing Wedge Distal Femoral Osteotomy

BACKGROUND

Recent studies have reported that lateral hinge fracture (LHF) has a negative effect on bone healing at the osteotomy site after medial closing wedge distal femoral osteotomy (MCDFO). However, limited evidence exists in the literature regarding the predictive factors for LHF in MCDFO.

HYPOTHESIS

A large medial closing gap and a lateral hinge position in the supracondylar area would increase plain radiography-based and/or computed tomography (CT)-based LHF in MCDFO.

STUDY DESIGN

Case control study; Level of evidence, 3.

METHODS

We retrospectively evaluated 67 knees of 53 patients (mean age, 37.4 ± 16.9 years) who underwent MCDFO between May 2009 and June 2021. The surgical indications for MCDFO were genu valgum deformity combined with either lateral compartment osteoarthritis or recurrent patellar dislocation. The presence of LHF was evaluated based on immediate postoperative plain radiography and CT scans. The predictive factors for LHF in MCDFO were investigated using multivariate logistic regression analysis.

RESULTS

LHFs were identified in 21 knees (31.3%) through plain radiography and in 40 knees (59.7%) through CT. Multivariate logistic regression analysis showed that the medial closing gap and lateral hinge position were predictive factors for plain radiography- and CT-based LHF after MCDFO. Controlling for other variables, we found that an increase in the medial opening gap by 1 mm increased the likelihood of plain radiography-based LHF by a factor of 1.805 (95% CI, 1.291-2.525; P = .001) and CT-based LHF by 1.333 (95% CI, 1.003-1.772; P = .048). Moreover, a lateral hinge position in the supracondylar area increased the likelihood of plain radiography-based LHF by a factor of 9.870 (95% CI, 2.179-44.720; P = .003) and CT-based LHF by 5.686 (95% CI, 1.124-28.754; P = .036).

CONCLUSION

A large medial closing gap and lateral hinge position in the supracondylar area are associated with LHF in MCDFO. Care should be taken to prevent LHF in MCDFO with a large medial closing gap. Moreover, a lateral hinge position in the supracondylar area should be avoided to decrease the incidence of LHF in MCDFO.

A Combination of Surgical and Chemical Induction in a Rabbit Model for Osteoarthritis of the Knee

BACKGROUND

Appropriate animal models of osteoarthritis (OA) are essential to develop new treatment modalities for OA. A combination of surgical and chemical induction could be appropriate for OA models.

METHODS

Rabbit knee OA models developed by surgical induction (anterior cruciate ligament transection [ACLT]), chemical induction (monosodium iodoacetate [MIA] injection), and a combination of both were compared to assess compositional and structural destruction of the knee joint. Twenty-one New Zealand white rabbits were randomly divided into 3 groups to induce OA (group 1: ACLT, n = 3; group 2: MIA [3, 6, 9 mg] injection, n = 9; group 3: ACLT + MIA [3, 6, 9 mg] injection, n = 9).

RESULTS

In all groups, the Modified Mankin score was significantly higher in the osteoarthritis-induced knee than in the control. Modified Mankin scores were compared by category. The ACLT group was observed to score high in cartilage structure. In the MIA group, chondrocytes and matrix staining showed higher scores, and the ACLT+MIA group scored higher in all categories for cartilage structure, chondrocytes, matrix staining, and tidemark integrity. The ACLT + 3 mg MIA showed definite OA characteristics such as cartilage surface destruction and degeneration of cartilage layers, and the ACLT + 6 mg MIA and ACLT + 9 mg MIA showed more prominent OA characteristics such as cartilage surface destruction, matrix disorganization, and osteophyte formation.

CONCLUSION

The combination of MIA injection and ACLT could be an appropriate method for OA induction in rabbit models.

Accuracy of the Tibial Component Alignment by Extramedullary System Using Simple Radiographic References in Total Knee Arthroplasty

Background and Objectives: The tibial component alignment is an important issue for the longevity of total knee arthroplasty (TKA). The purpose of our study was to investigate the usefulness of proximal tibial references determined by pre-operative radiography and intraoperative C-arm-guided hip and ankle center marking for the extramedullary guided tibial cut in mild (<10°) and severe (≥10°) varus knee TKA. Materials and Methods: A total of 150 consecutive patients (220 cases) who underwent total knee arthroplasty who were recruited from July 2011 to April 2017 were reviewed retrospectively. Before surgery, the proximal tibial reference point and medio-lateral cut thickness difference were identified. Then, hip and ankle centers were checked using a C-arm intensifier intraoperatively. The hip−knee−ankle (HKA) alignment and medial proximal tibial angle (MPTA) were assessed pre-operatively and post-operatively. More than 3° varus or valgus of HKA alignment or tibial component angle was defined as an outlier. Results: Mean follow-up duration was 26.9 months. Among 220 cases, 111 cases are classified as mild varus group and 109 cases are classified as severe varus group. The HKA alignment is significantly improved (p < 0.001). The average tibial component angle after surgery is 90.1°. A total of 21 cases (9.5%) and 3 cases (1.4%) are classified as outliers of HKA alignment and MPTA, respectively. Among MPTA outliers, one case is in the mild varus group and two cases are in the in severe varus group (p = 0.62). Conclusion: Measurement of proximal tibial radiographic references and checking the C-arm-guided intraoperative hip and ankle center could be helpful to obtain the favorable coronal position of the tibial component in the extramedullary guided tibial cut.

Deep learning-based landmark recognition and angle measurement of full-leg plain radiographs can be adopted to assess lower extremity alignment

PURPOSE

Evaluating lower extremity alignment using full-leg plain radiographs is an essential step in diagnosis and treatment of patients with knee osteoarthritis. The study objective was to present a deep learning-based anatomical landmark recognition and angle measurement model, using full-leg radiographs, and validate its performance.

METHODS

A total of 11,212 full-leg plain radiographs were used to create the model. To train the data, 15 anatomical landmarks were marked by two orthopaedic surgeons. Mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), and hip-knee-ankle angle (HKAA) were then measured. For inter-observer reliability, the inter-observer intraclass correlation coefficient (ICC) was evaluated by comparing measurements from the model, surgeons, and students, to ground truth measurements annotated by an orthopaedic specialist with 14 years of experience. To evaluate test-retest reliability, all measurements were made twice by each measurer. Intra-observer ICCs were then derived. Performance evaluation metrics used in previous studies were also derived for direct comparison of the model's performance.

RESULTS

Inter-observer ICCs for all angles of the model were 0.98 or higher (p < 0.001). Intra-observer ICCs for all angles were 1.00, which was higher than that of the orthopaedic specialist (0.97-1.00). Measurements made by the model showed no significant systemic variation. Except for JLCA, angles were precisely measured with absolute error averages under 0.52 degrees and proportion of outliers under 4.26%.

CONCLUSIONS

The deep learning model is capable of evaluating lower extremity alignment with performance as accurate as an orthopaedic specialist with 14 years of experience.

LEVEL OF EVIDENCE

III, retrospective cohort study.