Isolated high tibial osteotomy is appropriate in less than two-thirds of varus knees if excessive overcorrection of the medial proximal tibial angle should be avoided

[Medial closing wedge osteotomy for correction of valgus deformity]

OBJECTIVE

Correction of a proximal tibial valgus deformity.

INDICATIONS

Lateral osteoarthritis of the knee or cartilage damage in a valgus deformity > 5° with a medial proximal tibial angle (MPTA) > 90°.

CONTRAINDICATIONS

Medial proximal tibial angle < 90°, medial cartilage damage, medial meniscus loss.

SURGICAL TECHNIQUE

Skin incision medial of the tibial tuberosity approximately 8-10 cm. Insertion of two converging guidewires directly above the pes anserinus, ascending obliquely, and ending at the tip of the fibula. Control of the wire position with the image intensifier. Osteotomy with an oscillating saw. Removal of the wedge and closure of the osteotomy. Osteosynthesis with a medial angle-stable plate.

POSTOPERATIVE MANAGEMENT

Partial load bearing with 10-20 kg for 2 weeks, then step-wise increase in load. Mobility: free.

RESULTS

We performed this surgery in the manner described in 21 patients with lateral osteoarthritis or cartilage damage (17 men, 4 women, average age: 51 years). The valgus deformity was reduced from an average of 5.6 to -0.5°. The KOOS-PS (Knee Injury and Osteoarthritis Outcome Score-Physical Function Short-form) score decreased significantly from 39.1 ± 14 to 25.8 ± 20 points.

Around-the-knee osteotomies part 1: definitions, rationale and planning-state of the art

Knee osteotomies are essential orthopedic procedures with the ability to preserve the joint and correct ligament instabilities. Literature supports the correlation between lower limb malalignment and outcomes after knee ligament reconstruction and cartilage procedures. Concepts such as joint line obliquity, posterior tibial slope angle, and intra-articular deformity correction are integral components of both preoperative planning and postoperative evaluations. The concept of preserving and/or restoring joint line congruence during simultaneous correction of varus or valgus deformity can be achieved through several different approaches. With advancements in osteotomy research and surgical planning technology, the surgical decision-making has increased in complexity. Based upon a patient's specific deformity, decisions need to be made whether to perform a single-level (proximal tibia or distal femur) versus double-level (both proximal tibia and distal femur) osteotomy, and whether to correct deformity in a single plane (coronal or sagittal) or perform a biplanar osteotomy, correcting two of the malalignments in either coronal, sagittal, or axial planes. Osteotomy procedures prioritize safety, reproducibility, precision, and meticulous planning. Equally important is the proactive management of possible complications and the implementation of preventive strategies for complications such as hinge fractures and unintentional changes to alignment in other planes. This review navigates the intricate landscape of lower limb alignment, commencing with foundational definitions and rationale for performing osteotomies, progressing through the planning phase, and addressing the critical aspect of complication prevention, all while looking ahead to anticipate future advancements in this field. However, rotational osteotomies and tibial tubercle osteotomies in isolation or as an adjunct procedure are beyond the scope of this review.

Postoperative patient-reported outcome measures after medial open-wedge high tibial osteotomy was improved by decreased joint line convergence angle

PURPOSE

To evaluate the relationship between pre- and postoperative joint line convergence angle (JLCA) changes and patient-reported outcome measures related to medial open-wedge high tibial osteotomy (MOWHTO).

METHODS

Sixty-one patients (71 knees) who underwent MOWHTO were examined. Preoperative and 2-year postoperative radiographic parameters (hip-knee-ankle angle, weight-bearing line ratio, medial proximal tibial angle and JLCA) were measured, and knee injury and osteoarthritis outcome scores (KOOS) were assessed. Patients were divided into two groups: group D (decreased JLCA compared with preoperative status) included 44 knees with a ΔJLCA < 0° and group I (increased JLCA and no-change JLCA compared with preoperative status) included 27 knees with a ΔJLCA ≥ 0°. KOOS sub-scores and the proportion of patients whose improvement exceeded the minimum clinically important difference (MCID) were compared between both groups using Student's t tests, Mann-Whitney U tests and chi-square tests. Multiple regression analysis was performed to determine the factor that had an influential effect on the postoperative KOOS total.

RESULTS

Significant differences in 2-year postoperative KOOS were observed between the two groups, including total, symptom, pain and activities of daily living scores. Group D had significantly more patients who achieved MCID for both KOOS symptoms and pain scores than group I did. Multivariate analysis indicated that JLCA change and body mass index were significantly associated with the postoperative KOOS total.

CONCLUSION

Patients with decreased JLCA had better 2-year post-MOWHTO KOOS and better symptom and pain improvements. Therefore, strategies that reduce JLCA are crucial to improving clinical outcomes, and efforts should be made to improve JLCA in surgical techniques.

LEVEL OF EVIDENCE

Level Ⅳ, Case series.

Around-the-knee osteotomies part II: Surgical indications, techniques and outcomes - State of the art

Recent advances in surgical techniques and planning for knee-based osteotomies have led to improvements in addressing lower extremity malalignment. Part 1 of this review presented the biomechanical and clinical rationale of osteotomies, emphasizing the importance of osteotomies for restoring normal knee kinematics. In Part 2 of this review, indications, surgical technique and outcomes of osteotomies to correct coronal, sagittal and axial plane deformities will be examined. Traditional high tibial and distal femoral osteotomies will be discussed in addition to more recent advanced techniques including biplanar corrections and double-level osteotomies, as well as slope-correcting osteotomies. Patient-specific instrumentation and its use in more complex corrections will also be addressed.

Comparison of the indications for high tibial osteotomy and double-level osteotomy for the correction of diverse lower-leg deformities in an Asian population with medial compartment osteoarthritis: a retrospective observational study

PURPOSE

Double-level osteotomy (DLO) for knee osteoarthritis is becoming increasingly popular to achieve superior anatomical correction. This study aimed to compare the indication for open-wedge high tibial osteotomy (OWHTO) and DLO and to investigate preoperative bone morphology.

METHODS

Data of 166 knees treated with osteotomy were evaluated. The weight-bearing line ratio, mechanical lateral distal femoral angle (mLDFA), and mechanical medial proximal tibial angle (mMPTA) were measured. Bone deformity assessment and osteotomy simulation were conducted. Normal values of mLDFA and mMPTA were defined as 85-90°. Bone deformity was classified into four patterns: femoral, tibial, both, and no deformity. Simulation was performed to achieve a postoperative weight-bearing line ratio of 62%. Distal femoral osteotomy (DFO) or OWHTO was performed to achieve an mLDFA of 85° or mMPTA of up to 95°. If the postoperative parameter remained outside the correctable limit, DLO was performed. Cases were classified according to the corrective surgery performed, and those that could not be corrected after DLO were classified into the uncorrectable group.

RESULTS

Femoral, tibial, both, and no deformities were observed in 14.2%, 37.8%, 10.7%, and 33.9% of cases, respectively. No cases were classified into the DFO group; however, 53.6%, 38.1%, and 8.3% were classified into the OWHTO, DLO, and uncorrectable groups, respectively.

CONCLUSION

Bone deformity differed among cases, and only one-third had tibial deformity. OWHTO and DLO were indicated in approximately 50% and 40% of cases, respectively. Our study results reinforce the importance of evaluating leg morphology before surgical planning to achieve acceptable alignment.

Slope Osteotomies in the Setting of Anterior Cruciate Ligament Deficiency

➤ Posterior tibial slope (PTS) of ≥12° represents an important risk factor for both anterior cruciate ligament (ACL) injury and ACL reconstruction failure.➤ PTS measurements can significantly differ on the basis of the imaging modality and the measurement technique used. PTS should be measured on strictly lateral radiographs, with a recommended proximal tibial length of 15 cm in the image. The PTS measurement can be made by placing 2 circles to define the proximal tibial axis, 1 just below the tibial tubercle and another 10 cm below it. PTS measurements are underestimated when made on magnetic resonance imaging and computed tomography.➤ Slope-reducing osteotomies can be performed using a (1) supratuberosity, (2) tubercle-reflecting transtuberosity, or (3) infratuberosity method. The correction target remains a topic of debate. Although it is controversial, some authors recommend overcorrecting the tibial slope slightly to a range of 4° to 6°. For instance, if the initial slope is 12°, a correction of 6° to 8° should be performed, given the target tibial slope of 4° to 6°.➤ Clinical outcomes following slope-reducing osteotomies have been favorable. However, potential complications, limited data with regard to the impact of slope-reducing osteotomies on osteoarthritis, and uncertainty with regard to the effects on the patellofemoral joint are notable concerns.➤ Patients with complex deformities may need biplanar osteotomies to comprehensively address the condition.

Clinical and Radiological Outcomes of Medial Meniscal Allograft Transplantation Combined With Realignment Surgery

BACKGROUND

The outcomes of medial meniscal allograft transplantation (MMAT) combined with high tibial osteotomy (HTO) compared with isolated MMAT remain unclear.

PURPOSE

To compare the clinical and radiological results of MMAT combined with HTO and isolated MMAT.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This retrospective study included 42 consecutive patients, who were divided into group M (isolated MMAT; n = 22) and group H (MMAT combined with HTO with a varus angle >3°; n = 20). Group differences in subjective knee scores, isokinetic muscle strength test, and radiological outcomes (Kellgren-Lawrence grade, mechanical axis, graft extrusion, graft status, and articular cartilage loss) were compared.

RESULTS

The mean follow-up period was 29.2 ± 4.9 months and 27.4 ± 5.3 months for groups M and H, respectively. The Lysholm score improved from 55.4 ± 9.5 to 81.3 ± 9.7 and from 52.6 ± 8.9 to 84.2 ± 10.2 in groups M and H, respectively (both P < .001). The International Knee Documentation Committee subjective score improved from 51.4 ± 10.3 to 79.6 ± 9.4 and from 49.3 ± 11.4 to 81.4 ± 8.3 in groups M and H, respectively (both P < .001). Both groups showed no significant differences in subjective knee scores and isokinetic extensor strength at the final follow-up. The rate of preoperative and postoperative high International Cartilage Regeneration & Joint Preservation Society grade (≥3) did not differ between the 2 groups. Group M showed greater coronal graft extrusion than did group H (3.3 ± 0.7 mm vs 2.7 ± 0.8 mm; P = .014); the rate of pathologic graft extrusion (≥3 mm) was not higher in group M (40.9%) than in group H (20%) with the number of patients available (P = .143). Both groups showed no significant difference in the graft status. Graft tears were observed in 2 patients (9%) in group M and 1 patient (5%) in group H (P = .607).

CONCLUSION

Clinical scores significantly improved after isolated MMAT and MMAT combined with HTO compared with preoperative values, and their short-term outcomes were similar. Postoperative graft extrusion was greater in patients who underwent isolated MMAT, implying that active correction of varus alignment during MMAT may help in intra-articular biomechanics.

Development of an automatic surgical planning system for high tibial osteotomy using artificial intelligence

BACKGROUND

This study proposed an automatic surgical planning system for high tibial osteotomy (HTO) using deep learning-based artificial intelligence and validated its accuracy. The system simulates osteotomy and measures lower-limb alignment parameters in pre- and post-osteotomy simulations.

METHODS

A total of 107 whole-leg standing radiographs were obtained from 107 patients who underwent HTO. First, the system detected anatomical landmarks on radiographs. Then, it simulated osteotomy and automatically measured five parameters in pre- and post-osteotomy simulation (hip knee angle [HKA], weight-bearing line ratio [WBL ratio], mechanical lateral distal femoral angle [mLDFA], mechanical medial proximal tibial angle [mMPTA], and mechanical lateral distal tibial angle [mLDTA]). The accuracy of the measured parameters was validated by comparing them with the ground truth (GT) values given by two orthopaedic surgeons.

RESULTS

All absolute errors of the system were within 1.5° or 1.5%. All inter-rater correlation confidence (ICC) values between the system and GT showed good reliability (>0.80). Excellent reliability was observed in the HKA (0.99) and WBL ratios (>0.99) for the pre-osteotomy simulation. The intra-rater difference of the system exhibited excellent reliability with an ICC value of 1.00 for all lower-limb alignment parameters in pre- and post-osteotomy simulations. In addition, the measurement time per radiograph (0.24 s) was considerably shorter than that of an orthopaedic surgeon (118 s).

CONCLUSION

The proposed system is practically applicable because it can measure lower-limb alignment parameters accurately and quickly in pre- and post-osteotomy simulations. The system has potential applications in surgical planning systems.

Joint line and knee osteotomy

This review explores the intricate relationship between knee osteotomy and frontal plane joint line orientation, emphasizing the dynamic nature of the joint line's influence on knee forces and kinematics. Consideration of coronal alignments, knee phenotypes, and associated angles (medial proximal tibial angle (MTPA), lateral distal femoral angle (LDFA), joint line convergence angle (JLCA)) becomes crucial in surgical planning to avoid joint line deformities. The double-level osteotomy is to be considered a valid option, especially for severe deformities; however, the target patient cannot be selected solely based on high predicted postoperative joint line obliquity (JLO) and MPTA.

The influence of the weight-bearing state on three-dimensional (3D) planning in lower extremity realignment - analysis of novel vs. state-of-the-art planning approaches

BACKGROUND

The use of 3D planning to guide corrective osteotomies of the lower extremity is increasing in clinical practice. The use of computer-tomography (CT) data acquired in supine position neglects the weight-bearing (WB) state and the gold standard in 3D planning involves the manual adaption of the surgical plan after considering the WB state in long-leg radiographs (LLR). However, this process is subjective and dependent on the surgeons experience. A more standardized and automated method could reduce variability and decrease costs.

PURPOSE

The aim of the study was (1) to compare three different three-dimensional (3D) planning modalities for medial open-wedge high tibial osteotomy (MOWHTO) and (2) to describe the current practice of adapting NWB CT data after considering the WB state in LLR. The purpose of this study is to validate a new, standardized approach to include the WB state into the 3D planning and to compare this method against the current gold standard of 3D planning. Our hypothesis is that the correction is comparable to the gold standard, but shows less variability due compared to the more subjective hybrid approach.

METHODS

Three surgical planning modalities were retrospectively analyzed in 43 legs scheduled for MOWHTO between 2015 and 2019. The planning modalities included: (1) 3D hybrid (3D non-weight-bearing (NWB) CT models after manual adaption of the opening angle considering the WB state in LLR, (2) 3D NWB (3D NWB CT models) and (3) 3D WB (2D/3D registration of 3D NWB CT models onto LLR to simulate the WB state). The pre- and postoperative hip-knee-ankle angle (HKA) and the planned opening angle (°) were assessed and differences among modalities reported. The relationship between the reported differences and BMI, preoperative HKA (LLR), medial meniscus extrusion, Outerbridge osteoarthritis grade and joint line convergence angle (JLCA) was analyzed.

RESULTS

The mean (std) planned opening angle of 3D hybrid did not differ between 3D hybrid and 3D WB (0.4 ± 2.1°) (n.s.) but was higher in 3D hybrid compared to 3D NWB (1.1° ± 1.1°) (p = 0.039). 3D WB demonstrated increased preoperative varus deformity compared to 3D NWB: 6.7 ± 3.8° vs. 5.6 ± 2.7° (p = 0.029). Patients with an increased varus deformity in 3D WB compared to 3D NWB (> 2 °) demonstrated more extensive varus alignment in LLR (p = 0.009) and a higher JLCA (p = 0.013).

CONCLUSION

Small intermodal differences between the current practice of the reported 3D hybrid planning modality and a 3D WB approach using a 2D/3D registration algorithm were reported. In contrast, neglecting the WB state underestimates preoperative varus deformity and results in a smaller planned opening angle. This leads to potential under correction in MOWHTO, especially in patients with extensive varus deformities or JLCA.

CLINICAL RELEVANCE

Incorporating the WB state in 3D planning modalities has the potential to increase accuracy and lead to a more consistent and reliable planning in MOWHTO. The inclusion of the WB state in automatized surgical planning algorithms has the potential to reduce costs and time in the future.

Constitutional varus knee due to tibial deformity is common and represents a good indication for high tibial osteotomy in Japanese population: Consideration of 1010 knees

PURPOSE

This study aimed to elucidate the characteristics of varus knee deformities in the Japanese population, prevalence of various around knee osteotomy procedures and influence of femoral and tibial bowing.

METHODS

Varus knee deformity was defined as a weight-bearing line ratio of <50%. A total of 1010 varus knees were selected from 1814 varus knees with weight-bearing full-length radiographs, obtained at two facilities, based on exclusion criteria. Various parameters were measured, and around knee osteotomy simulations based on the deformity centre were conducted using digital planning tools. Bowing of the femoral and tibial shafts was measured, with bowing defined as follows: ≤ -0.6° indicating lateral bowing and ≥ 0.6° indicating medial bowing. Statistical analysis was performed to investigate age-related correlations and their impact on surgical techniques.

RESULTS

The study revealed that the proximal tibia was the centre of deformity in Japanese varus knees (42.8%), and high tibial osteotomy was frequently indicated (81.6%). Age demonstrated a mild correlation with femoral shaft bowing (r = -0.29), leading to an increase in the mechanical lateral distal femoral angle and to a decrease in the hip-knee-ankle angle and weight-bearing line ratio (r = -0.29, 0.221, 0.219). The tibial shaft bowing was unaffected by age (r = -0.022).

CONCLUSION

A significant proportion of Japanese individuals with varus knees exhibit a deformity centre located in the proximal tibia, making them suitable candidates for high tibial osteotomy. No age-related alterations were discerned in tibial morphology, indicating that the occurrence of constitutional varus knees is attributable to tibial deformities in the Japanese patient cohort.

LEVEL OF EVIDENCE

Level IV.

No clinical outcome difference between varus phenotypes after medial opening-wedge high tibial osteotomy at 2 years follow-up

PURPOSE

Clinical studies regarding medial open-wedge high tibial osteotomy (MOWHTO) often analyse a large group of mechanical varus knees rather than differentiating for its primary varus-inducing component. This study aims to compare the radiological and clinical outcomes of the most prevalent varus malalignment phenotypes using the coronal plane alignment of the knee (CPAK) classification.

METHODS

MOWHTO cases with minimal 2-year clinical follow-up were retrospectively selected from a knee osteotomy database (2016-2020). Based on the medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA), subjects were allocated to the correct CPAK phenotype pre- and postoperatively. Clinical outcomes were the numeric rating scale (NRS), the knee injury and osteoarthritis outcome score (KOOS) and the therapeutic response rate (TRR) at 2-year follow-up. Inter-observer correlation coefficient (ICC) and unpaired student t test were performed for cross-phenotype comparison.

RESULTS

One hundred thirty-five (135) subjects were found eligible (53.0 years old ±9.6 [19-77], 72% male, 53% left-sided). The most prevalent preoperative phenotype was CPAK 1 (n = 70 (52%)) and the postoperative phenotype was CPAK 6 (n = 66 (49%)). All CPAK phenotypes improved significantly relative to baseline but cross-phenotype comparison yielded no significant differences in clinical outcome. The TRR at 2 years was 67% for CPAK 1, 69% for CPAK 2 and 87% for CPAK 4. The TRR for CPAK 6 was 64% compared with 80% for CPAK 9, which was not significantly different.

CONCLUSION

At 2-year follow-up, no clinically significant differences are observed between different CPAK phenotypes. Accurate MOWHTO corrections provide significant clinical improvement even in the femoral-driven varus knee and the constitutional varus knee dominated by intra-articular wear. The clinical indication for MOWHTO performance should not be reduced to the medial arthritic varus knee with underlying tibial varus alone.

LEVEL OF EVIDENCE

Level IV, retrospective comparative study.

Multicentric development and validation of a multi-scale and multi-task deep learning model for comprehensive lower extremity alignment analysis

Osteoarthritis of the knee, a widespread cause of knee disability, is commonly treated in orthopedics due to its rising prevalence. Lower extremity misalignment, pivotal in knee injury etiology and management, necessitates comprehensive mechanical alignment evaluation via frequently-requested weight-bearing long leg radiographs (LLR). Despite LLR's routine use, current analysis techniques are error-prone and time-consuming. To address this, we conducted a multicentric study to develop and validate a deep learning (DL) model for fully automated leg alignment assessment on anterior-posterior LLR, targeting enhanced reliability and efficiency. The DL model, developed using 594 patients' LLR and a 60%/10%/30% data split for training, validation, and testing, executed alignment analyses via a multi-step process, employing a detection network and nine specialized networks. It was designed to assess all vital anatomical and mechanical parameters for standard clinical leg deformity analysis and preoperative planning. Accuracy, reliability, and assessment duration were compared with three specialized orthopedic surgeons across two distinct institutional datasets (136 and 143 radiographs). The algorithm exhibited equivalent performance to the surgeons in terms of alignment accuracy (DL: 0.21 ± 0.18°to 1.06 ± 1.3°vs. OS: 0.21 ± 0.16°to 1.72 ± 1.96°), interrater reliability (ICC DL: 0.90 ± 0.05 to 1.0 ± 0.0 vs. ICC OS: 0.90 ± 0.03 to 1.0 ± 0.0), and clinically acceptable accuracy (DL: 53.9%-100% vs OS 30.8%-100%). Further, automated analysis significantly reduced analysis time compared to manual annotation (DL: 22 ± 0.6 s vs. OS; 101.7 ± 7 s, p ≤ 0.01). By demonstrating that our algorithm not only matches the precision of expert surgeons but also significantly outpaces them in both speed and consistency of measurements, our research underscores a pivotal advancement in harnessing AI to enhance clinical efficiency and decision-making in orthopaedics.

Relationship between increased knee joint line obliquity after medial open-wedge high tibial osteotomy and patient-reported outcome measures

INTRODUCTION

This study evaluated the correlation between postoperative knee joint line obliquity after medial open-wedge high tibial osteotomy and patient-reported outcome measures excluding excessively overcorrected knees. This study further identified preoperative radiological factors related to the increased postoperative knee joint line obliquity.

MATERIALS AND METHODS

We retrospectively evaluated patients who underwent medial open-wedge high tibial osteotomy between March 2013 and March 2021. Postoperative excessively overcorrected knees with hip-knee-ankle angle > 7° were excluded. We investigated radiological parameters and patient-reported outcome measures preoperatively and at the last follow-up. The following radiologic parameters were measured: hip-knee-ankle angle, weight-bearing line ratio, mechanical medial proximal tibial angle, mechanical lateral distal femoral angle, lateral distal tibial angle, joint line convergent angle, knee joint line obliquity, ankle joint line obliquity, hip abduction angle, tibial posterior slope, Carton-Deschamps index, and patella tilting angle. Clinical outcomes were evaluated using Japanese knee outcome measures. This assessment criterion is based on the Western Ontario McMaster Universities Arthritis Index and MOS Short Form 36. Multiple regression analysis was performed to evaluate the association between postoperative knee joint line obliquity and patient-reported outcome measures or preoperative radiological factors (P < .05).

RESULTS

A total of 52 knees were included. The mean age at the time of the surgery was 61.6 ± 9.0 years and the mean follow-up period was 30.6 ± 10.1 months. Increased postoperative knee joint line obliquity was associated with lower Japanese knee outcome measures. The preoperative hip-knee-ankle angle was significantly associated with postoperative knee joint line obliquity.

CONCLUSIONS

Increased knee joint line obliquity after medial open-wedge high tibial osteotomy is associated with inferior clinical outcomes. Care should be given to the center of the rotational angulation in around-knee osteotomy to avoid postoperative increased knee joint line obliquity.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

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.

Higher conversion rate to knee arthroplasty in female patients following medial open-wedge high tibial osteotomy

PURPOSE

Most studies about medial open-wedge high tibial osteotomy (HTO) reported outcomes without focusing on gender differences. Therefore, the study compared the long-term survival rate and postoperative subjective knee function after HTO in female versus male patients with symptomatic medial compartment knee osteoarthritis.

METHODS

The data of three cohorts with long-term outcomes were analysed (n = 245; 32% females; age: 49 ± 7 years; Kellgren Lawrence Grade I 6.1%, II 32.7%, III 42.4%; IV 18.8%). The minimum follow-up was at least 6 years or an earlier conversion to total knee arthroplasty (TKA). The gender-specific survival rate after HTO was calculated after 5 and 10 years and compared using Kaplan-Meier analysis and the logrank test. Baseline characteristics and subjective knee function (International Knee Documentation Committee [IKDC]/Lysholm) were analysed between both genders.

RESULTS

Forty of 78 (51.3%) women and 41 of 167 men (24.5%) underwent TKA. HTO survival in females was significantly lower (p = 0.0010). The 5- and 10-year survival rates were 85.9% and 62.6% for females and 93.4% and 77.7% for males. In females and males, from preoperative to the last follow-up, the IKDC (43 ± 15 to 58 ± 17; 47 ± 14 to 67 ± 18) and the Lysholm (42 ± 18 to 72 ± 18; 55 ± 22 to 77 ± 23) improved significantly (all p < 0.0001). Females had significantly lower preoperative and postoperative IKDC (p = 0.0438; p = 0.0035) and Lysholm scores (p = 0.0002; p = 0.0323). But the absolute improvements of the IKDC and Lysholm were not significantly different between genders.

CONCLUSIONS

Females had higher conversion rates to TKA and lower knee function at the last follow-up. However, preoperative knee function was lower in females and the absolute improvement following HTO was similar for both genders. In general, females benefit from HTO to treat medial knee arthritis, and TKA could be postponed for half of female patients for more than 10 years. However, surgeons must be aware of the described inferior outcomes in females for realistic patient expectation management.

LEVEL OF EVIDENCE

Level II.

Medial opening wedge high tibial osteotomy for the treatment of medial unicompartmental knee osteoarthritis: A state-of-the-art review

Medial unicompartmental knee osteoarthritis is a common condition that is frequently associated with significant pain and dysfunction. Medial opening wedge high tibial osteotomy (MOWHTO) offers a unique opportunity to preserve the knee joint and potentially alter the course of the degenerative process. Recent advances in this field of surgery have enabled surgeons to perform a MOWHTO in a safe, reliable and reproducible manner. This state-of-the-art review highlights the most important advances in the field of MOWHTO. Key concepts related to patient selection, pre-operative planning, surgical accuracy and patient outcome are considered. The importance of an individualized approach is emphasized and its influence on the future direction of the procedure is discussed.

Bilateral Inverted V-shaped High Tibial Osteotomy: A Case Report

The article describes the case of a young patient with bilateral genu varum deformity, limiting her mobility. The therapeutic decision was a staged reverse V-shaped tibial osteotomy on both knees at a six-month interval. The surgery faced infectious complications on the left side, requiring additional treatment. Despite this, the patient achieved successful correction, with wound healing and bone consolidation. Preoperative planning was crucial, determining specific correction angles for each knee. The reverse V-shaped osteotomy demonstrated satisfactory functional outcomes compared to other techniques. The conclusion emphasizes the effectiveness of reverse V-shaped high tibial osteotomy (HTO) in addressing varus tibial deformities, providing an alternative before considering total knee arthroplasty. Multicenter studies and long-term evaluations are recommended to refine this surgical procedure.

Artificial intelligence-based analyses of varus leg alignment and after high tibial osteotomy show high accuracy and reproducibility

PURPOSE

The aim of this study was to investigate the performance of an artificial intelligence (AI)-based software for fully automated analysis of leg alignment pre- and postoperatively after high tibial osteotomy (HTO) on long-leg radiographs (LLRs).

METHODS

Long-leg radiographs of 95 patients with varus malalignment that underwent medial open-wedge HTO were analyzed pre- and postoperatively. Three investigators and an AI software using deep learning algorithms (LAMA™, ImageBiopsy Lab, Vienna, Austria) evaluated the hip-knee-ankle angle (HKA), mechanical axis deviation (MAD), joint line convergence angle (JLCA), medial proximal tibial angle (MPTA), and mechanical lateral distal femoral angle (mLDFA). All measurements were performed twice and the performance of the AI software was compared with individual human readers using a Bayesian mixed model. In addition, the inter-observer intraclass correlation coefficient (ICC) for inter-observer reliability was evaluated by comparing measurements from manual readers. The intra-reader variability for manual measurements and the AI-based software was evaluated using the intra-observer ICC.

RESULTS

Initial varus malalignment was corrected to slight valgus alignment after HTO. Measured by the AI algorithm and manually HKA (5.36° ± 3.03° and 5.47° ± 2.90° to - 0.70 ± 2.34 and - 0.54 ± 2.31), MAD (19.38 mm ± 11.39 mm and 20.17 mm ± 10.99 mm to - 2.68 ± 8.75 and - 2.10 ± 8.61) and MPTA (86.29° ± 2.42° and 86.08° ± 2.34° to 91.6 ± 3.0 and 91.81 ± 2.54) changed significantly from pre- to postoperative, while JLCA and mLDFA were not altered. The fully automated AI-based analyses showed no significant differences for all measurements compared with manual reads neither in native preoperative radiographs nor postoperatively after HTO. Mean absolute differences between the AI-based software and mean manual observer measurements were 0.5° or less for all measurements. Inter-observer ICCs for manual measurements were good to excellent for all measurements, except for JLCA, which showed moderate inter-observer ICCs. Intra-observer ICCs for manual measurements were excellent for all measurements, except for JLCA and for MPTA postoperatively. For the AI-aided analyses, repeated measurements showed entirely consistent results for all measurements with an intra-observer ICC of 1.0.

CONCLUSIONS

The AI-based software can provide fully automated analyses of native long-leg radiographs in patients with varus malalignment and after HTO with great accuracy and reproducibility and could support clinical workflows.

LEVEL OF EVIDENCE

Diagnostic study, Level III.

A significant rate of tibial overcorrection with an increased JLO occurred after isolated high tibial osteotomy without considering international consensus

PURPOSE

The recent ESSKA consensus recommendations defined indications and outlined parameters for osteotomies around a degenerative varus knee. The consensus collated these guidelines based on the published literature available to answer commonly asked questions including the importance of identifying the site and degree of the lower limb deformity. In the consensus, the authors suggest that a knee joint line obliquity (JLO) greater than 5° or a planned medial proximal tibial angle (MPTA) > 94° preferentially indicates a double level osteotomy (DLO) compared to an isolated opening wedge high tibial osteotomy (OWHTO). This study aimed to analyze the corrections performed on a cohort of isolated opening wedge high tibial osteotomies (OWHTOs) prior to the recent ESSKA recommendations, with a focus on the impact of knee joint line obliquity (JLO) and medial proximal tibial angle (MPTA) on the choice of osteotomy procedure.

METHODS

This monocentric, retrospective study included 129 patients undergoing medial OWHTO for symptomatic isolated medial knee osteoarthritis (Ahlbäck grade I or II) and a global varus malalignment (hip-knee-ankle angle ≤ 177°). An automated software trained to automatically detect lower limb deformity was implemented using patients preoperative long leg alignment X-rays to identify suitability for an isolated HTO in knee varus deformity. Based on the ESSKA recommendations, the site of the osteotomy was identified as well as the degree of correction required. The ESSKA consensus considers avoiding an isolated high tibial osteotomy if the planned resultant knee joint line orientation exceeds 5 ̊ or MPTA exceeds 94°. A preoperative abnormal MPTA was defined by a value lower than 85° and a preoperative abnormal LDFA by a value greater than 90°. The cases of DLO or DFO suggested by the software and the number of extra-tibial anomalies were collected. Multiple linear regression models were developed to establish a relationship between preoperative values and the risk of being outside of ESSKA recommendations postoperatively.

RESULTS

Based on ESSKA recommendations and on threshold values considered abnormal, the software suggested a DLO in 17.8% (n = 23/129) of cases, a distal femoral osteotomy in 27.9% (n = 36/129) of cases and advised against an osteotomy procedure in 24% (n = 31/129) of cases. The software detected a femoral anomaly in 34.9% (n = 45/129) of cases and an JLCA > 6° in 9.3% (n = 12/129). Postoperatively, the MPTA exceeds 94° in 41.1% (n = 53/129) and the JLO exceeds 5° in 29.4% (n = 38/129). On multivariate analysis, a high preoperative MPTA was associated with higher risk of postoperative MPTA > 94° (R2 = 0.36; p < 0.001). Similarly, the probability of the software advising a DLO or DFO was associated with the presence of an "normal" preoperative MPTA (R2 = 0.42; p < 0.001) or an abnormal preoperative LDFA (R2 = 0.48; p < 0.001) or a planned JLO > 5° (R2 = 0.27; p < 0.001).

CONCLUSIONS

Analysis of patients who underwent an isolated OWHTO prior to the ESSKA guidelines, demonstrated a significant rate of post-operative tibial overcorrection and a resultant increased JLO. Pre-operative planning that considers the ESSKA guidelines, allows for better identification of those patients requiring a DFO or DLO and avoidance of resultant post-operative deformities.

LEVEL OF EVIDENCE

IV, case-series.

Editorial Commentary: Alignment for Open-Wedge High Tibial Osteotomy Can Be Planned Using the Hip-Knee-Ankle Angle and the Weightbearing Line

Correct alignment of the limb mechanical axis is a principal goal of open-wedge high tibial osteotomy and determines successful postoperative outcomes. Excessive postoperative joint line obliquity must be avoided. A mechanical medial proximal tibial angle (mMPTA) less than 95° results in poor outcomes. Preoperative planning is commonly performed using a picture archiving and communication system; however, this is time-consuming and sometimes inaccurate because many landmarks and parameters need to be confirmed manually. Hip-knee-ankle (HKA) angle and weightbearing line (WBL) percentage are perfectly correlated to the Miniaci angle when planning open-wedge high tibial osteotomy, and ΔmMPTA and ΔWBL percentage are nearly perfectly correlated with the ΔHKA angle. Surgeons can easily measure the Miniaci angle according to the preoperative HKA and preoperative WBL percentage without digital software, and mMPTA greater than 95° can be avoided. Finally, bony and soft tissue components must be considered during preoperative planning. Medial soft tissue laxity must be specifically avoided.

Clinical and Radiological Outcomes of Double-Level Osteotomy Versus Open-Wedge High Tibial Osteotomy for Bifocal Varus Deformity

Background

In bifocal varus deformity, double-level osteotomy (DLO) is advocated to treat lower limb alignment to prevent an adverse increase in joint line obliquity.

Purpose/Hypothesis

The purpose of this study was to compare the clinical and radiological results after DLO and open-wedge high tibial osteotomy (OWHTO) in patients with combined varus deformity. It was hypothesized that DLO would improve clinical results without increasing the complication rate compared with OWHTO.

Study Design

Cohort study; Level of evidence, 3.

Methods

Inclusion criteria were medial tibiofemoral compartment pain, varus knee deformity with an abnormal medial proximal tibial angle <84° and a lateral distal femoral angle >90°, a functional anterior cruciate ligament, failure of nonoperative treatment, and a minimum 2-year follow-up with all clinical and radiological data. The rate of return to work or sports; the Knee injury and Osteoarthritis Outcome Score (KOOS); the University of California, Los Angeles (UCLA) activity score; and patient satisfaction were assessed at a minimum of 2 years of follow-up. Statistical comparison of the 2 groups was made using the chi-square or Student t test.

Results

A total of 69 consecutive patients were analyzed, of whom 38 underwent OWHTO and 31 underwent DLO surgery. A significant between-group difference was found for all radiological parameters; in particular, there was less joint line obliquity after DLO compared with OWHTO (1.7° vs 5.6°; P < .001). DLO provided better outcomes compared with OWHTO regarding the UCLA score (4.3 vs 6.7; P < .001) and patient satisfaction (2.6 vs 3.9; P < .001), but no significant difference in KOOS or return to work or sports was observed. The OWHTO group had more hinge fractures than the DLO group (34.2% vs 12.9%; P < .001).

Conclusion

For combined tibial and femoral varus deformity, DLO produced more physiologic joint line obliquity with slightly improved UCLA and patient satisfaction scores. A greater incidence of hinge fracture was observed after isolated OWHTO compared with DLO due to a larger tibial correction; however, this had little effect on clinical results at the 2-year follow-up.

Current clinical practice of knee osteotomy in the Netherlands

BACKGROUND

Realignment osteotomies is gaining popularity amongst Dutch orthopaedic surgeons. Exact numbers and used standards in clinical practice concerning osteotomies are unknown due to the absence of a national registry. The aim of this study was to investigate the national statistics of performed osteotomies, utilized clinical workups, surgical techniques, and post-operative rehabilitation standards in the Netherlands.

METHOD

Dutch orthopaedic surgeons, all members of the Dutch Knee Society, received a web-based survey between January and March 2021. This electronic survey contained 36 questions, subdivided into: general surgeon-related information, number of performed osteotomies, inclusion of patients, clinical workup, surgical techniques, and post-operative management.

RESULTS

86 orthopaedic surgeons filled in the questionnaire, of whom 60 perform realignment osteotomies around the knee. All the 60 responders (100%) perform high tibial osteotomies and 63.3% additionally perform distal femoral osteotomies, while 30% perform double level osteotomies. Discrepancies in surgical standards were reported regarding to inclusion criteria, clinical workup, surgical techniques, and post-operative strategies.

CONCLUSIONS

In conclusion, this study got more insight in knee osteotomy clinical practices as applied by Dutch orthopaedic surgeons. However, there are still important discrepancies which pleads for more standardization based on available evidence. A (inter)national knee osteotomy registry, and even more so, a (inter)national registry for joint preserving surgeries could be helpful to achieve more standardization and treatment insights. Such a registry could improve all aspects of osteotomies and its combinations with other joint-preserving interventions towards evidence for personalised treatments.

Clinical Effect of Isolated Lateral Closing Wedge Distal Femoral Osteotomy Compared to Medial Opening Wedge High Tibial Osteotomy for the Correction of Varus Malalignment: A Propensity Score-Matched Analysis

BACKGROUND

Recent evidence questions the role of medial opening wedge high tibial osteotomy (mowHTO) in the correction of femoral-based varus malalignment because of the potential creation of an oblique knee joint line. However, the clinical effectiveness of alternatively performing an isolated lateral closing wedge distal femoral osteotomy (lcwDFO), in which the mechanical unloading effect in knee flexion may be limited, is yet to be confirmed.

PURPOSE/HYPOTHESIS

The purpose of this article was to compare clinical outcomes between patients undergoing varus correction via isolated lcwDFO or mowHTO, performed according to the location of the deformity, in a cohort matched for confounding variables. It was hypothesized that results from undergoing isolated lcwDFO for symptomatic varus malalignment would not significantly differ from the results after mowHTO.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Consecutive patients who underwent isolated mowHTO or lcwDFO according to a tibial- or femoral-based symptomatic varus deformity between January 2010 and October 2019 were enrolled. Confounding factors, including age at surgery, sex, body mass index, preoperative femorotibial axis, and postoperative follow-up, were matched using propensity score matching. The International Knee Documentation Committee (IKDC) Subjective Knee Form, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lysholm score, Tegner Activity Scale, and visual analog scale (VAS) for pain were collected preoperatively and at a minimum of 24 months postoperatively.

RESULTS

Of 535 knees assessed for eligibility, 50 knees (n = 50 patients, n = 25 per group) were selected by propensity score matching. Compared with preoperatively, both the mowHTO group (IKDC, 55.1 ± 16.5 vs 71.3 ± 14.7, P = .002; WOMAC, 22.0 ± 18.0 vs 9.6 ± 10.8, P < .001; Lysholm, 55.2 ± 23.1 vs 80.7 ± 16, P < .001; VAS, 4.1 ± 2.4 vs 1.6 ± 1.8, P < .001) and the lcwDFO group (IKDC, 49.4 ± 14.6 vs 66 ± 20.1, P = .003; WOMAC, 25.2 ± 17.0 vs 12.9 ± 17.6, P = .003; Lysholm, 46.5 ± 15.6 vs 65.4 ± 28.7, P = .011; VAS, 4.5 ± 2.2 vs 2.6 ± 2.5, P = .001) had significantly improved at follow-up (80 ± 20 vs 81 ± 43 months). There were no significant differences between the groups at baseline, at final follow-up, or in the amount of clinical improvement in any of the outcome parameters (P > .05; respectively).

CONCLUSION

Performing both mowHTO or lcwDFO yields significant improvement in clinical outcomes if performed at the location of the deformity of varus malalignment. These findings confirm the clinical effectiveness of performing an isolated lcwDFO in femoral-based varus malalignment, which is comparable with that of mowHTO in the correction of varus malalignment.

Favorable rates of return to activity and work following lateral closing wedge distal femoral osteotomy for femoral-based symptomatic varus malalignment: an analysis at a mean 6-year follow-up

PURPOSE

To evaluate return to sport (RTS), work (RTW) and clinical outcomes following lateral closing wedge distal femoral osteotomy (LCW-DFO) for symptomatic femoral varus malalignment.

METHODS

Consecutive patients who underwent LCW-DFO for symptomatic varus malalignment between 12/2007 and 03/2018 were included. The International Knee Documentation Committee (IKDC) Score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lysholm score, Tegner Activity Scale, and visual analogue scale (VAS) for pain were collected preoperatively and at a minimum of 24 months postoperatively. RTS and RTW were assessed by questionnaire.

RESULTS

Thirty-two patients (mean age: 45.9 ± 12.3 years), who underwent LCW-DFO for femoral-based varus malalignment (6.4 ± 3.0°), were included at a mean follow-up of 72.7 ± 39.1 months. The patient collective significantly improved in IKDC (51.8 ± 12.3 to 61.8 ± 21.5, p = 0.010; 95% CI = 3-21), WOMAC (26.7 ± 17.6 to 12.5 ± 13.5; p < 0.001; 95% CI = 21-6) and Lysholm (46.5 ± 19.4 to 67.9 ± 22.8 points (p < 0.01; 95% CI = 9-31)) scores at final follow-up. The VAS for pain reduced significantly postoperatively (4.8 ± 2.3 points to 2.6 ± 2.3 points (p = 0.002; 95% CI = 0-3)). Following LCW-DFO, 96% of patients returned to sports at a mean of 5.3 ± 2.9 months. Yet, a shift to lower impact sports compared to one year preoperatively was observed, with patients participating in a significantly lower number of high-impact disciplines (p = 0.024) and fewer hours in high-impact sports (p = 0.034). Twenty-three out of 24 patients returned to work at a mean 11.4 ± 10.9 weeks, with 18 patients reporting a similar or superior working ability.

CONCLUSION

Undergoing isolated LCW-DFO for symptomatic femoral-based varus malalignment enabled the vast majority of patients to RTS and RTW along with a significant functional improvement at mid-term follow-up. However, patients' expectations have to be adequately managed regarding a limited probability to return to high-impact sports and work after surgery.

LEVEL OF EVIDENCE

Retrospective case series; Level IV.

Potential anatomic risk factors resulting oversized postoperative medial proximal tibial angle after double level osteotomy

BACKGROUND

Double level osteotomy (DLO) has been introduced to prevent increased postoperative joint line obliquity. However, although DLO is planned, knees with postoperative medial proximal tibial angle (MPTA) > 95° in preoperative surgical planning are present. This retrospective study aimed to evaluate risk factors for an MPTA > 95° in preoperative surgical planning for DLO in patients with varus knee osteoarthritis (OA).

METHODS

A total of 168 knees that underwent osteotomies around the knee for varus knee OA were enrolled. The hip-knee-ankle angle (HKA), weight-bearing line (WBL) ratio, mechanical lateral distal femoral angle (mLDFA), joint line convergence angle (JLCA) and mechanical medial proximal tibial angle (mMPTA) were measured on preoperative radiographs. The postoperative WBL ratio was planned to be 62.5%. When the postoperative mMPTA was more than 95° in isolated high tibial osteotomy (HTO), (DLO) was planned so that the postoperative mLDFA was 85°, and residual deformity was corrected by HTO. Knees with postoperative mMPTA ≤ 95° and > 95° were classified into the correctable group and uncorrectable group, respectively.

RESULTS

DLO was required in 101 knees (60.1%). Among them, 41 knees (40.6%) were classified into the uncorrectable group. Binomial logistic regression analysis showed that preoperative JLCA and mMPTA were independent predictors in the uncorrectable group.

CONCLUSIONS

Even with DLO, postoperative mMPTA was more than 95° in approximately 40% of cases. Preoperative increased JLCA and decreased mMPTA were risk factors for a postoperative mMPTA of > 95° after DLO.

Double level osteotomy for medial osteoarthritis and bifocal varus malalignment has excellent short-term results while maintaining physiologic radiographic joint parameters

PURPOSE

The purpose of this study was to prospectively evaluate the clinical and radiological results of double level osteotomy (distal femoral lateral closed wedge and proximal tibial medial open wedge) in medial osteoarthritis and varus malalignment due to bifocal deformity of femur and tibia.

METHODS

From 2017 to 2019 all cases of DLO in osteoarthritic varus malaligned knees with bifocal deformity (femoral and tibial deformity) were prospectively enrolled into this observational therapeutic study. Evaluation was performed preoperatively, at six, twelve, 18 and 24 months with regard to survival (not requiring arthroplasty), functional outcome [subjective International Knee Documentation Committee score (IKDC), Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome score (KOOS) and Tegner Activity Scale], pain level (numeric rating scale), subjective satisfaction (rating 1-5), radiographic parameters on a pre-and postoperative full leg x-rays (mechanical axis, mechanical proximal tibial and distal femoral angles) and complications. For statistical evaluation student's t test, Mann-Whitney U test and Wilcoxon-signed-rank test were used.

RESULTS

Fifty-two consecutive cases in 48 patients were enrolled in the study. Three cases were excluded, resulting in a follow-up rate of 94%. No arthroplasties were performed within follow-up. All functional outcome scores substantially and significantly increased as early as six months after the index procedure and further increased until final follow-up (p < 0.001). Pain level significantly decreased (p < 0.001). At final follow-up all patients stated that they would retrospectively undergo the operation again, and rated the result with 4.5 ± 0.6 out of 5 (3-5). Radiographic parameters were within physiological limits postoperatively. No severe complications occurred.

CONCLUSIONS

Double level osteotomy has excellent short-term results while maintaining physiological radiographic parameters. Therefore, it should be an integral part and standard procedure in realignment surgery for monocompartimental osteoarthritis.

LEVEL OF EVIDENCE

IV (prospective observational therapeutic study).

Pre-surgery HKA angle and WBL percentage are nearly perfectly correlated to the Miniaci angle when planning open wedge high tibial osteotomies

PURPOSE

To investigate the conversion formulas between the Miniaci angle, pre-surgery parameters, and changes in pre-surgery parameters in open-wedge high tibial osteotomy (OWHTO), including hip-knee-ankle (HKA) angle, weight-bearing line (WBL) percentage, mechanical medial proximal tibial angle (mMPTA), ΔHKA angle, ΔWBL percentage, ΔmMPTA, and other parameters.

METHODS

From January 2012 to December 2019, 247 lower limbs of 144 patients with medial unicompartmental knee osteoarthritis combined with proximal tibia vara were enrolled. Inclusion criteria were adults, medial unicompartmental knee osteoarthritis, Kellgren-Lawrence classification grade ≤ Ⅲ, mMPTA ≤85° and mechanical lateral distal femoral angle (mLDFA) is normal (85°-90°), and patella facing anterior in the bipedal standing position. Exclusion criteria were history of fracture, trauma, or orthopaedic surgery; developmental dysplasia of the hip or femoral head necrosis; femoral bowing deformity; deformity of the tibial shaft; and leg length discrepancy. Using standing whole-leg radiographs (WLRs), an OWHTO simulation was performed to determine the Miniaci angle by delivering the WBL to the Fujisawa point. The relationship of the Miniaci angle, the pre-surgery parameters, and the changes in pre-surgery parameters were analysed by spearman's correlation and linear regression analyses. The relationship between the post-surgery HKA angle and pre-surgery parameters was analysed by multiple linear regression model.

RESULTS

The Miniaci angle showed a near perfect correlation with the pre-surgery HKA angle (y=-1.05x+192.10, r²=0.99), pre-surgery WBL percentage (y=-0.25x+15.14, r²=0.97), ΔHKA angle (y=1.04x-0.03, r²=1.00), ΔWBL percentage (y=0.25x-0.52, r²=0.97), and ΔmMPTA (y=1.04x-0.03, r²=1.00). The ΔHKA angle showed nearly perfect correlation with the ΔmMPTA (y=1.00x, r²=1.00), and ΔWBL percentage (y=0.24x-0.47, r²=0.97).

CONCLUSIONS

The pre-surgery HKA angle, pre-surgery WBL percentage, ΔHKA angle, ΔWBL, and ΔmMPTA percentage are nearly perfectly correlated to the Miniaci angle, while the ΔmMPTA and ΔWBL percentage are nearly perfectly correlated to the ΔHKA angle.

CLINICAL RELEVANCE

With the conversion formulas determined in the current study, surgeons can calculate the Miniaci angle based on the pre-surgery parameters without the assistance of digital software for complex surgical simulation. The Miniaci angle is closely related to the gap of the medial opening wedge. Based on the Miniaci angle and the depth of the osteotomy, surgeons can calculate the gap required prior to surgery using trigonometric functions and then simply measure the gap during surgery.

Factors Associated With Unfavorable Radiological Outcomes After Opening-Wedge High Tibial Osteotomy for Varus Knees

BACKGROUND

Corrective osteotomy around the knee is based on deformity profiles of the femoral and tibial sides. Opening-wedge high tibial osteotomy (OWHTO) can be favored if the outcomes are not different, even if there is a certain degree of abnormal parameters after correction.

PURPOSE/HYPOTHESIS

The purpose of this study was to identify the factors associated with unfavorable radiological outcomes after OWHTO for varus knees. Our hypothesis was that there would be an optimal situation in which double-level osteotomy (DLO) has advantages over isolated OWHTO and an optimal cutoff value of structural parameters for which DLO should be considered in patients with severe varus knees.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The radiological and clinical outcomes of 337 patients who underwent OWHTO were retrospectively evaluated. A subgroup analysis was performed according to the weightbearing line ratio (WBLR) (group 1: <25th percentile; group 2: 25th-75th percentile; and group 3: >75th percentile) and factors associated with unfavorable radiological outcomes. For the assessment of cutoff values of the parameters favoring DLO, unfavorable radiological outcomes were categorized as follows: (1) medial proximal tibial angle (MPTA) >95°, (2) joint-line convergence angle (JLCA) >4° (insufficient medial release), (3) JLCA <0° (medial instability), (4) recurrence of a varus deformity, and (5) lateral hinge fracture.

RESULTS

The mean follow-up period was 66.2 ± 19.1 months. A low preoperative WBLR was related to a larger preoperative to postoperative change (Δ) in the WBLR, a larger reduction in coronal translation, a larger ΔMPTA, a wide preoperative lateral joint space, and a narrow preoperative medial joint space (P < .001, P < .001, P < .001, P = .016, and P = .003, respectively). However, only an MPTA >95° was significantly related to a low WBLR in the subgroup analysis according to unfavorable radiological outcomes (P = .038). The cutoff value of ΔWBLR causing an MPTA >95° was 46.5%, which showed a good area under the curve of 0.800, with a sensitivity of 74.4% and a specificity of 82.7%. The clinical outcomes significantly improved at the final follow-up compared with those preoperatively, with no significant differences between the WBLR groups.

CONCLUSION

A ΔWBLR ≥46.5% led to an MPTA >95°. However, clinical outcomes were not affected. DLO should be considered if the surgeon desires a postoperative MPTA ≤95°.

Double level osteotomy for genu varum: Is a return to sport possible?

INTRODUCTION

A double level osteotomy (DLO) may be indicated in patients with genu varum when the deformity involves both the tibia and femur. These patients, who are often young and active, have a high functional demand and hope for a rapid return to sport. The purpose of our study was to assess return to sport and functional outcomes following DLO for symptomatic genu varum.

MATERIALS AND METHODS

A total of 40 patients (mean age 45.5±2 years) who underwent a DLO between 2018 and 2020, performed in 2 different hospitals, were reviewed after a minimum follow-up of 1-year. The mean initial varus was 11±2°. The type of sport and frequency of participation (UCLA activity score) as well as time to return to sport and level of activity recovered were defined as the primary endpoints. Functional scores were also assessed with the knee injury and osteoarthritis outcome score (KOOS).

RESULTS

At the last follow-up, 87.5% (n=35) of patients reported that they had returned to sport. The mean time to return to sport was 6±1 months with a significant difference (p<0.001) between the pre- and postoperative UCLA activity scores. There was a strong correlation between the presence of a joint line obliquity >3° and decreased functional outcomes (p<0.0001). The overall KOOS score improved (p<0.001) by a mean of 38.6 points after the correction. The 8 lateral cortical fractures (Takeuchi type I and II) and the 2 medial cortical fractures (Nakayama type 1) that were found had no impact on functional outcomes (p>0.05).

CONCLUSION

Our findings demonstrated that DLO provided rapid return to sport, thus making it possible to meet the functional demands and expectations of patients.

LEVEL OF EVIDENCE

IV; Retrospective study.

Optimizing indications and technique in osteotomies around the knee

Osteotomies around the knee represent a valid surgical treatment in young active patients affected by unicompartmental osteoarthritis and/or knee ligament instability.

This review article describes the main osteotomies performed around the knee and their optimization, with particular attention to indications and surgical technique in light of the most recent literature and author experience.

Further developments have to be expected from technological advances, focusing particularly on surgical planning and the control of intraoperative deformity correction by pre-shaped cutting blocks.

Excessively Increased Joint-Line Obliquity After Medial Opening-Wedge High Tibial Osteotomy Is Associated With Inferior Radiologic and Clinical Outcomes: What Is Permissible Joint-Line Obliquity

PURPOSE

This study aimed to evaluate the permissible joint-line obliquity (JLO) based on radiologic and clinical outcomes with midterm follow-up after medial open-wedge high tibial osteotomy (MOWHTO).

METHODS

Patients who had undergone MOWHTO from March 2014 to May 2016 were retrospectively evaluated. They were divided into 4 groups based on JLO as represented by postoperative medial proximal tibial angle (MPTA). Radiologic parameters including MPTA, joint-line orientation angle (JLOA), joint-line convergence angle (JLCA), posterior tibial slope, weightbearing line ratio (WBLR), and coronal translation were analyzed. Clinical outcomes were evaluated with American Knee Society Score (AKSS), Western Ontario and McMaster University Index, and short-form 36 health survey (SF-36). The changes between preoperation and final follow-up in JLOA and MPTA were defined as ΔJLOA and ΔMPTA.

RESULTS

A total of 135 knees were finally included (MPTA ≤90.32° as group I; 90.33° to 92.62° as group II; 92.74° to 95.22° as group III; and ≥95.23° as group IV). The last follow-up MPTA, JLOA, and JLCA values were different between the groups (P < .001, P < .001, and P = .015, respectively). WBLR and JLOA positively correlated with MPTA; however, WBLR showed an abrupt increase at MPTA >96.5°, and the JLOA distribution tended to be greater than the regression line at MPTA >96°. Moreover, ΔJLOA was not as large as ΔMPTA. The percentage of patients attaining a minimal clinically important difference was significantly lower in the AKSS-functional score and SF-36 physical component summary in group IV (P = .008 and 0.021, respectively).

CONCLUSION

The JLOA did not change as much as the MPTA, but an MPTA >95.2° abruptly increased the JLOA and valgus overcorrection after MOWHTO. Poor clinical outcomes were more evident in excessive MPTA (>95.2°) than in mildly undercorrected or properly corrected MPTA (<95.2°).

LEVEL OF EVIDENCE

III, retrospective cohort study.

Editorial Commentary: Avoid Creating an Oblique Joint Line After an Opening Medial Wedge High Tibial Osteotomy

A medial opening wedge high tibial osteotomy is a cost-effective procedure for younger patients with symptomatic medial compartment knee arthritis. A high rate of success can be expected, but excessive postoperative joint line obliquity is associated with inferior clinical outcomes. If preoperative planning predicts that the postoperative medial proximal tibial angle, the medial angle between the tibial anatomical axis and the joint line of the proximal tibia, will exceed 95°, a surgeon should consider performing a double-level osteotomy (combined proximal tibial and distal femoral osteotomies).

Improved Clinical Outcome and High Rate of Return to Low-Impact Sport and Work After Knee Double Level Osteotomy for Bifocal Varus Malalignment

PURPOSE

To evaluate return to sport (RTS) and work (RTW), as well as clinical outcomes following double level osteotomy (DLO) via combined medial open wedge high tibial osteotomy and lateral closing wedge distal femoral osteotomy for bifocal symptomatic varus malalignment, and to compare these outcome parameters between patients undergoing a single surgery and those undergoing a two-stage procedure.

METHODS

Consecutive patients who underwent DLO for symptomatic varus malalignment between 12/2007 and 03/2018 were enrolled. Patients converted to arthroplasty (n = 3) during follow-up were excluded. Outcome measures included the International Knee Documentation Committee (IKDC) Score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lysholm score, Tegner Activity Scale, and visual analog scale (VAS) for pain, which were collected preoperatively and at a minimum of 24 months postoperatively. RTS and RTW were evaluated by questionnaire. Outcome measures were compared between DLO performed in a single- versus a two-stage surgery.

RESULTS

Thirty-two patients (mean age: 44.2 ± 12.6 years), who underwent DLO for varus malalignment (10.1° ± 2.9°) were included at a mean follow-up of 56.9 ± 35.3 months (range: 24-148). Compared to preoperatively, these patients significantly improved in IKDC (50.4 ± 13.9 to 66.1 ± 15.4; P < .001), WOMAC (29.7 ± 19.2 to 11.8 ± 13.5; P < .001) and Lysholm (53.6 ± 23.6 to 73.1 ± 23.6; P = .002) scores at final follow-up. For the WOMAC score, 78% of the patients included reached the minimally important clinical difference, along with a significant reduction of the VAS for pain (5.0 ± 3.0 to 2.5 ± 2.4; P < .001). Postoperatively, 96% of patients returned to sport after 7.7 ± 4.8 months, but at a lower frequency (P = .010) and to fewer disciplines (P = .005) with a shift to low-impact sports. 90% of the patients returned to work at a mean 5.9 ± 9.4 months, with 79% reporting a similar or superior working ability. Patients undergoing a two-stage procedure recovered to full physical working ability at a significantly longer duration, as compared to a single-stage procedure (9.8 ± 3.8 vs 9.0 ± 13.1 months; P = .047).

CONCLUSION

The majority of patients undergoing DLO for symptomatic varus malalignment, who were not converted to arthroplasty, experienced clinically significant functional improvement at mid-term follow-up. Return to sport and work rates in these patients were high; however, a shift to lower-impact sports disciplines was observed. Similar clinical outcomes can be expected when performing DLO in a single surgery or a two-stage procedure.

LEVEL OF EVIDENCE

Retrospective case series; Level IV.

Surgical planning of osteotomies around the knee differs between preoperative standing and supine radiographs in nearly half of cases

Background

To evaluate the difference in surgical planning of osteotomies around the knee between preoperative standing and supine radiographs and to identify risk factors for discrepancies in surgical planning.

Methods

This study included 117 knees of 100 patients who underwent osteotomies around the knee for knee osteoarthritis with genu varum. Surgical planning was performed so that the target point of the postoperative weight-bearing line (WBL) ratio was 62.5% in preoperative standing and supine radiographs. If the opening gap would be > 13 mm in open-wedge high tibial osteotomy (OWHTO), closed-wedge HTO (CWHTO) was planned. If the postoperative mMPTA would be > 95° in isolated HTO, double-level osteotomy (DLO) was planned. In DLO, lateral closed-wedge distal femoral osteotomy was performed so that the postoperative mechanical lateral distal femoral angle (mLDFA) was 85°, and any residual varus deformity was corrected with HTO.

Results

Surgical planning differed between standing and supine radiographs in 43.6% of cases. In all knees for which surgical planning differed between standing and supine radiographs, a more invasive type of osteotomy was suggested by standing radiographs than by supine radiographs. The risk factors for discrepancies in surgical planning were a lower WBL ratio in standing radiographs and a lower joint line convergence angle in supine radiographs.

Conclusions

Surgical planning of DLO, CWHTO and OWHTO, in standing radiographs differed from that in supine radiographs in nearly half of the cases. Surgical planning based on standing radiographs leads to more invasive surgical procedures compared to supine radiographs.

Outcomes of double level osteotomy for osteoarthritic knees with severe varus deformity. A systematic review

BACKGROUND

When correcting severe genu varus deformity, knee surgeons must choose between performing a single or double-level osteotomy. This systematic review aims to provide this equipoise with some clarity.

PATIENTS AND METHODS

We conducted this study following the Preferred Reporting Items for Systematic Reviews and Meta-analyses Statement (PRISMA) and the Cochrane Handbook for systematic reviews and meta-analysis. Studies evaluating the effect of the double level osteotomy (DLO) or those comparing it to high tibial osteotomy (HTO) from all regions and written in any language were included.

RESULTS

Six studies were included in this systematic review. They were prepared and analysed using Review Manager V5.0 [Computer Program] (RevMan5). Performing DLO resulted in restoring patellar height, joint-line convergence angle (JLCA), and mMPTA to normal values. DLO was also more successful at avoiding joint line obliquity (JLO) in severe varus deformity when compared to HTO (P < 0.001). No significant difference was reported between the two cohorts regarding the mLPTA. DLO resulted in satisfactory short term KOOS and IKDC scores. The complication rate after DLO was 2.28%.

CONCLUSIONS

DLO showed a low complication rate and satisfactory short term KOOS and IKDAC scores. Randomised control trials with long term follow-up comparing the DLO and HTO are recommended.

10-Year Survival Rates After High Tibial Osteotomy Using Angular Stable Internal Plate Fixation: Case Series With Subgroup Analysis of Outcomes After Combined Autologous Chondrocyte Implantation and High Tibial Osteotomy

Background:

Good-to-excellent midterm results after high tibial osteotomy (HTO) to treat medial compartment cartilage defects or osteoarthritis (OA) have been published, but little is known about long-term survival rates in terms of conversion to total knee arthroplasty (TKA) using angular stable internal plate fixation.

Purpose:

To determine TKA-free survival rates and functional and radiological outcomes at 10 years after HTO. A subgroup analysis of patients who underwent combined HTO and autologous cartilage implantation (ACI) was also performed.

Study Design:

Case series; Level of evidence, 4.

Methods:

Included were 125 patients with a mean follow-up of 9.90 ± 2.25 years; 90 patients underwent HTO for medial OA, and 35 patients underwent ACI and HTO for medial focal cartilage defects. Functional outcome measures included visual analog scale (VAS) for pain, Lysholm, International Knee Documentation Committee (IKDC), and Knee injury and Osteoarthritis Outcome Score (KOOS) subscales and KOOS₄ (average of 4 KOOS subscales: Pain, Symptoms, Sport, and Quality of Life). Radiological outcomes included lateral distal femoral angle, medial proximal tibial angle, and joint line convergence angle.

Results:

Overall, 16 patients required conversion to TKA at a mean 86.75 ± 25.73 months (10-year survival rate, 87.2%). Only 2 patients in the HTO+ACI subgroup required a conversion to TKA (10-year survival rate, 94.3%). The complication rate for all patients was 8.8%. In both the HTO and HTO+ACI subgroups, VAS pain levels decreased and Lysholm scores increased significantly from pre- to postoperatively (P < .001). A higher preoperative Tegner score led to a significantly lower risk for conversion to TKA (P = .001), and a preoperative body mass index of ≥35 was associated with a significantly higher risk (P = .019), as was female sex (P = .046). Radiological parameters remained within physiological ranges. The postoperative joint line conversion angle did correlate with postoperative functional outcome but not with TKA conversion.

Conclusion:

Long-term results of HTO for medial compartment OA or cartilage defects with underlying varus deformity were good to excellent. In particular, patients who underwent HTO+ACI presented excellent long-term survival rates. HTO, therefore, delays or prevents TKA implantation, especially in young, active patients with medial compartment damage.

Iatrogenic ischiofemoral impingement due to high tibial osteotomy with overvalgization: a case report

Background

Open wedge high tibial osteotomy is a standard procedure for frontal realignment. It is indicated in varus knee with reduced mechanical medial proximal tibia angle. Overcorrection producing a mechanical medial proximal tibia angle out of the normal range (85–90°) is not recommended because this would lead to unphysiological joint-line orientation. Osteotomies around the knee also influence the adjacent ankle and hip joints. For the hip, it is known that frontal alignment of the leg influences the ischiofemoral space. A decreased ischiofemoral space can lead to painful impingement between the ischial bone and the lesser trochanter.

Case presentation

A 53-year-old German woman presented with severe ischiofemoral impingement symptoms and valgus malalignment of the left leg after open wedge high tibial osteotomy, which was indicated and performed by an orthopedic surgeon with intention to treat medial knee pain due to degenerative arthritis of the medial compartment years after medial meniscectomy. The mechanical medial proximal tibia angle was 100.5°. We performed closed wedge high tibial osteotomy producing a mechanical medial proximal tibia angle of 90.0° and normal joint-line orientation. The hip pain was gone immediately after the surgery, and the patient had no signs of ischiofemoral impingement or hip pain at last follow-up 12 months after closed wedge high tibial osteotomy.

Conclusions

Frontal realignment osteotomy around the knee can create problems at adjacent joints. Overvalgization of the proximal tibia made the patient compensate by hyperadduction of the hip to enable full foot sole contact with the floor. Hyperadduction of the hip decreased the ischiofemoral space, leading to severe impingement. Therefore, meticulous planning of osteotomies is important not to produce unphysiological situations or unwanted negative effects at the level of an adjacent joint.

Joint Line Obliquity Does Not Affect the Outcomes of Opening Wedge High Tibial Osteotomy at an Average 10-Year Follow-up

BACKGROUND

A significant number of high tibial osteotomies (HTOs) result in an overcorrected tibia and subsequent excessive lateral joint line obliquity (JLO). The correlation between excessive JLO and poor outcomes is controversial.

PURPOSE

To evaluate the prognostic factors (including a pathological postoperative JLO) related with the outcomes of opening wedge HTO at 10 years of follow-up.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

All patients undergoing HTO between 2004 and 2017 for medial osteoarthritis and with a postoperative hip-knee-ankle angle between 176° and 185° were included. Clinical evaluation included Knee Society Score (KSS; knee score and function score), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and visual analog scale for pain. Several mechanical and anatomic angles were measured pre- and postoperatively on long-leg weightbearing radiographs. Abnormal JLO was defined as a Mikulicz-joint line angle (MJL) ≥94° or a mechanical medial proximal tibial angle (mMPTA) ≥95°. Regression analysis was performed to evaluate the association between independent variables and each outcome. A Kaplan-Meier cumulative survival analysis was performed.

RESULTS

A total of 92 knees in 76 patients were included. The mean age of the patients was 53.5 years (SD, 9.7 years), and the mean follow-up was 129.4 months (SD, 44.4 months). Increased JLO was associated with a significant preoperative varus deformity (small preoperative hip-knee-ankle angle), increased mechanical lateral distal femoral angle, increased joint line congruency angle, and increased knee-ankle joint angle. Male sex was associated with better WOMAC scores (P = .0277), and increased body mass index (BMI) was associated with inferior WOMAC scores (P = .0024). A good preoperative range of motion was associated with better knee score (P = .0399) and function score (P = .0366) on the KSS. An increased BMI was associated with inferior KSS function scores (P = .0317). MJL ≥94° and mMPTA ≥95° were not associated with inferior WOMAC or KSS outcomes. With indication to total knee arthroplasty as an endpoint, Kaplan-Meier analysis showed a survival rate of 98.7% at 5 years, 95.5% at 10 years, and 92.7% at 12 years.

CONCLUSION

Increased lateral JLO (MJL ≥94° or mMPTA ≥95°) was not correlated with the clinical outcomes of opening wedge HTO at 10 years of follow-up.

Dislocated hinge fractures are associated with malunion after lateral closing wedge distal femoral osteotomy

PURPOSE

To evaluate the incidence, morphology, and associated complications of medial cortical hinge fractures after lateral closing wedge distal femoral osteotomy (LCW-DFO) for varus malalignment and to identify constitutional and technical factors predisposing for hinge fracture and consecutive complications.

METHODS

Seventy-nine consecutive patients with a mean age of 47 ± 12 years who underwent LCW-DFO for symptomatic varus malalignment at the authors' institution between 01/2007 and 03/2018 with a minimum of 2-year postoperative time interval were enrolled in this retrospective observational study. Demographic and surgical data were collected. Measurements evaluating the osteotomy cut (length, wedge height, hinge angle) and the location of the hinge (craniocaudal and mediolateral orientation, relation to the adductor tubercle) were conducted on postoperative anterior-posterior knee radiographs and the incidence and morphology of medial cortical hinge fractures was assessed. A risk factor analysis of constitutional and technical factors predisposing for the incidence of a medial cortical hinge fracture and consecutive complications was conducted.

RESULTS

The incidence of medial cortical hinge fractures was 48%. The most frequent morphological type was an extension fracture type (68%), followed by a proximal (21%) and distal fracture type (11%). An increased length of the osteotomy in mm (53.1 ± 10.9 vs. 57.7 ± 9.6; p = 0.049), an increased height of the excised wedge in mm (6.5 ± 1.9 vs. 7.9 ± 3; p = 0.040) as well as a hinge location in the medial sector of an established sector grid (p = 0.049) were shown to significantly predispose for the incidence of a medial cortical hinge fracture. The incidence of malunion after hinge fracture (14%) was significantly increased after mediolateral dislocation of the medial cortical bone > 2 mm (p < 0.05).

CONCLUSION

Medial cortical hinge fractures after LCW-DFO are a common finding. An increased risk of sustaining a hinge fracture has to be expected with increasing osteotomy wedge height and a hinge position close to the medial cortex. Furthermore, dislocation of a medial hinge fracture > 2 mm was associated with malunion and should, therefore, be avoided.

LEVEL OF EVIDENCE

Prognostic study; Level IV.

Association of Preoperative Tibial Varus Deformity With Joint Line Orientation and Clinical Outcome After Open-Wedge High Tibial Osteotomy for Medial Compartment Osteoarthritis: A Propensity Score-Matched Analysis

BACKGROUND

The correction of lower limb deformity should be performed at the site of deformity to maintain knee joint orientation. However, the effectiveness of open-wedge high tibial osteotomy (OWHTO) for treatment of medial osteoarthritis in varus malalignment without definite tibial varus deformity has not been confirmed.

PURPOSE/HYPOTHESIS

This study aimed to compare the clinical and radiologic outcomes after OWHTO in patients without tibial varus deformity versus patients with tibial varus deformity after matching for confounding factors. We hypothesized that these outcomes would be inferior in patients without tibial varus deformity.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The outcomes of 133 OWHTO operations for medial osteoarthritis in 107 patients were retrospectively reviewed after follow-up for >2 years. The patients were divided into group 1 (tibia with varus deformity, preoperative medial proximal tibial angle [MPTA] <85°) and group 2 (tibia without varus deformity, preoperative MPTA ≥85°). The confounding factors, including patient characteristics, preoperative limb alignment, degree of osteoarthritis, and correction angle, were matched using propensity score matching. The radiologic parameters, including MPTA and joint line obliquity, were evaluated preoperatively, between 6 and 12 months postoperatively, and at the last follow-up. The radiologic outcomes were assessed using the medial joint space width and mechanical hip-knee-ankle angle. The clinical outcomes were evaluated by the Hospital for Special Surgery knee score, Knee Society Score (KSS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. The clinical and radiologic outcomes were compared between the groups. The proportions of patients achieving improvement in the clinical outcome beyond the minimal clinically important difference (MCID) or minimally important change were compared between the groups.

RESULTS

After propensity score matching, 32 patients were selected for each group. The mechanical hip-knee-ankle angle was corrected without significant difference from a mean ± SD varus angle of 8.0°± 3.3° to valgus angle of -3.2°± 2.5° in group 1 and from varus 8.0°± 3.6° to valgus -3.9°± 1.7° in group 2. The preoperative joint line obliquity was greater in group 2 as compared with group 1 (2.2°± 2.2° vs -0.4°± 1.8°, P < .001). With a similar 10° correction angle, the postoperative MPTA and joint line obliquity were 96.6°± 2.5° and 5.3°± 2.3°, respectively, in group 2, which were greater than 94.0°± 2.6° and 3.5°± 1.8°, respectively, in group 1 (both P < .001). The changes in joint space width and mechanical hip-knee-ankle angle were not significantly different between the groups over the follow-up period. At the last follow-up, the postoperative KSS objective score and WOMAC pain score in terms of symptom improvement were not significantly different between groups (P = .092 and .068). However, the postoperative KSS and WOMAC functional scores were significantly worse in group 2 than in group 1 (77.3 ± 14.1 vs 84.4 ± 11.6, P = .044; 10.3 ± 9.2 vs 5.6 ± 7.2, P = .001). In group 1, 96.9% and 100% of patients showed improvements of >10 points in the KSS functional score and 15 points in the WOMAC functional score based on MCID or minimally important change. Meanwhile, 65.6% and 81.3% of patients in group 2, which were significantly lower than those of group 1, were improved beyond the MCID or minimally important change (P = .001 and .024, respectively).

CONCLUSION

In varus malalignment, the knee joint line was more oblique in patients without tibial varus deformity after OWHTO pre- and postoperatively. The clinical outcomes in terms of functional scores were inferior in patients without tibial varus deformity. However, the radiologic outcomes and symptomatic improvement after OWHTO were comparable regardless of the preoperative tibial varus deformity on midterm follow-up.

Increased joint obliquity after open-wedge high tibial osteotomy induces pain in the lateral compartment: a comparative analysis of the minimum 4-year follow-up outcomes using propensity score matching

PURPOSE

To analyze the effects of increased medial proximal tibial angle (MPTA) on the clinical outcomes and cartilage deterioration in the lateral compartment after a mean follow-up period of 4 years following open-wedge high tibial osteotomy (OWHTO) using propensity score matching (PSM) analysis.

METHODS

Among 376 knees treated with OWHTO for medial unicompartmental osteoarthritis with varus deformity, 36 knees with MPTA increase of > 95° and 108 knees with MPTA increase of < 95° at the final follow-up were included. The baseline prognostic factors [age, sex, preoperative hip-knee-ankle (HKA) angle, body mass index, and preoperative knee range of motion] were equalized between the 2 groups using PSM; consequently, 31 pairs of patients were compared. The radiographic and clinical outcomes, including lateral compartment pain, were assessed. For 18 patients in each group, second-look arthroscopy and cartilage status assessment were performed.

RESULTS

The preoperative demographics were similar between the groups. At the final follow-up, the HKA angle and joint line obliquity were significantly higher in the increased MPTA group. No significant differences were observed in the clinical outcomes between the groups. On second-look arthroscopy, significant cartilage deterioration of the lateral compartment was not observed in either group. Pain in the lateral compartment was experienced significantly more frequently in the increased MPTA group (p < 0.01).

CONCLUSION

Although excessively increased MPTA after HTO had no significant effects on the clinical outcomes and cartilage deterioration in the lateral compartment at the minimum 4-year follow-up, lateral compartment pain was experienced significantly more frequently in the increased MPTA group.

Factors related to the early outcome of medial open wedge high tibial osteotomy: coronal limb alignment affects more than cartilage degeneration state

INTRODUCTION

This study aimed to identify possible factors influencing the early outcome after medial open wedge high tibial osteotomy (MOWHTO).

MATERIALS AND METHODS

A total of 87 MOWHTO cases with a minimum of 2-year follow-up and second-look arthroscopic results available were enrolled. The cartilage degeneration state was evaluated by the International Cartilage Repair Society (ICRS) grading. Radiographic parameters including the hip-knee-ankle axis (HKA), medial proximal tibia angle (MPTA), posterior tibial slope, patellar height, mechanical lateral distal femoral angle (LDFA), joint line convergence angle (JLCA), joint line obliquity (JLO), and weight-bearing line ratio (WBLR) were measured. The pre-operative arthritic change was evaluated by Kellgren-Lawrence (KL) classification. According to the post-operative HKA, knees were divided into three (Under/Optimal/Over-correction) subgroups. Subjective International Knee Documentation Committee (IKDC) scores were evaluated and factors related to post-operative IKDC scores were analyzed.

RESULTS

The pre-operative HKA (P = 0.002), post-operative HKA (P = 0.007), pre-operative MPTA (P = 0.011), and pre-operative WBLR (P = 0.031) were significantly related to the post-operative IKDC score. Cartilage degeneration states evaluated from first and second-look arthroscopy were not associated with post-operative IKDC score. Subgroup analysis revealed that the Under-correction group had significantly lower post-operative IKDC scores compared to the Optimal and Over-correction group (P = 0.012 and P = 0.030, respectively).

CONCLUSION

Our result suggests that a sub-optimal correction of coronal limb alignment negatively affects the early outcome of MOWHTO. On the other hand, the effect of the degree of cartilage degeneration was not significant.

High Tibial Osteotomy for Varus Deformity of the Knee

High tibial osteotomy is a powerful technique to treat symptomatic varus deformity of the knee and is successful when properly indicated and performed. Indications include varus deformity with medial compartment osteoarthritis, cartilage or meniscus pathology. Several techniques exist to correct symptomatic varus malalignment along with concomitant procedures to restore cartilage or meniscus injuries. Evidence supporting high tibial osteotomy for symptomatic medial compartment pathology exists, which provides a durable solution for joint preservation. This review will discuss the indications, techniques, and outcomes for high tibial osteotomies used in the treatment of symptomatic varus deformity of the knee.

Knee Joint Line Obliquity Causes Tibiofemoral Subluxation That Alters Contact Areas and Meniscal Loading

BACKGROUND

Little scientific evidence is available regarding the effect of knee joint line obliquity (JLO) before and after coronal realignment osteotomy.

HYPOTHESES

Higher JLO would lead to abnormal relative position of the femur on the tibia, a shift of the joint contact areas, and elevated joint contact pressures.

STUDY DESIGN

Descriptive laboratory study.

METHODS

10 fresh-frozen human cadaveric knees (age, 59 ± 5 years) were axially loaded to 1500 N in a materials testing machine with the joint line tilted 0°, 4°, 8°, and 12° varus ("downhill" medially) and valgus, at 0° and 20° of knee flexion. The mechanical compression axis was aligned to the center of the tibial plateau. Contact pressure and contact area were recorded by pressure sensors inserted between the tibia and femur below the menisci. Changes in relative femoral and tibial position in the coronal plane were obtained by an optical tracking system.

RESULTS

Both medial and lateral JLO caused significant tibiofemoral subluxation and pressure distribution changes. Medial (varus) JLO caused the femur to subluxate medially down the coronal slope of the tibial plateau, and vice versa for lateral (valgus) downslopes (P < .01), giving a 6-mm range of subluxation. The areas of peak pressure moved 12 mm and 8 mm across the medial and lateral condyles, onto the downhill meniscus and the "uphill" tibial spine. Changes in JLO had only small effects on maximum contact pressures.

CONCLUSION

A 4° change of JLO during load bearing caused significant mediolateral tibiofemoral subluxation. The femur slid down the slope of the tibial plateau to abut the tibial eminence and also to rest on the downhill meniscus. This caused large movements of the tibiofemoral contact pressures across each compartment.

CLINICAL RELEVANCE

These results provide important information for understanding the consequences of creating coronal JLO and for clinical practice in terms of osteotomy planning regarding the effect on JLO. This information provides guidance regarding the choice of single- or double-level osteotomy. Excessive JLO alteration may cause abnormal tibiofemoral joint articulation and chondral or meniscal loading.

Osteotomy around the knee is planned toward an anatomical bone correction in less than half of patients

INTRODUCTION

In cases where the femur or tibial deformity is not correctly analysed, the corrective osteotomies may result in an oblique joint line. The aim of this study was to assess the preoperative deformity of patients due to undergo corrective osteotomy and the resulting abnormal tibial and femoral morphologies after the planned correction using 3D software.

METHODS

CT scans of 327 patients undergoing corrective osteotomy were retrospectively included. Each patient was planned using a software application and the simulated correction was validated by the surgeon. Following the virtual osteotomy, tibial and femoral coronal angular values were considered abnormal if the values were outside 97.5% confidence intervals for non-osteoarthritis knees. After virtual osteotomy, morphological abnormalities were split into two types. Type 1 was an under/overcorrection at the site of the osteotomy resulting in abnormal bone morphology. A type 2 was defined as an error in the site of the correction, resulting in an uncorrected abnormal bone morphology.

RESULTS

The global rate of planned abnormalities after tibial virtual osteotomy was 50.7% (166/327) with abnormalities type 1 in 44% and type 2 in 6.7%. After femoral virtual osteotomy the global rate was 6.7% (22/327) with only abnormalities type 1. A lower preoperative HKA was significantly associated with a non-anatomical correction (R²=0.12, p<0.001) for both femoral (R²=0.06, p<0.001) and tibial (R²=0.07, p<0.001) abnormalities.

CONCLUSION

Non-anatomical correction was found in more than half the cases analysed more frequently for preoperative global varus alignment. These results suggest that surgeons should considered anatomical angular values to avoid joint line obliquity.

LEVEL OF EVIDENCE

III; retrospective cohort study.

[The influence of axial deformities and their correction on the development and progression of osteoarthritis]

Die Beachtung der Beinachse und die Möglichkeiten zur deren Korrektur stellen beim jungen Patienten mit Arthrose ein Grundpfeiler der Therapie dar. Die Kombination einer Gelenksverletzung und einer Achsdeviation führt unweigerlich, je nach Ausmaß und Komorbiditäten, schon nach wenigen Jahren zur fortschreitenden Gonarthrose. Neben der genauen Deformitätenanalyse zur Osteotomieplanung, gilt es, Normbereiche der entsprechenden Winkel zu kennen und eine Zielgröße zur Achskorrektur festzulegen. Aus dem Repertoire der verschiedenen kniegelenksnahen Osteotomien sind dann die Nebeneffekte in Bezug auf patellofemorales Maltracking, ligamentäres Balancing und die Beinlänge abzuschätzen. Gerade im Hinblick auf mögliche (und wahrscheinliche) Folgeoperationen beim jungen Patienten müssen neue knöcherne Deformitäten oder ligamentäre Insuffizienzen, welche potenziell bei Überkorrektur entstehen, unbedingt vermieden werden.