Osteotomy around the knee: evolution, principles and results

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.

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.

A synoptic literature review of animal models for investigating the biomechanics of knee osteoarthritis

Osteoarthritis (OA) is a common chronic disease largely driven by mechanical factors, causing significant health and economic burdens worldwide. Early detection is challenging, making animal models a key tool for studying its onset and mechanically-relevant pathogenesis. This review evaluate current use of preclinical in vivo models and progressive measurement techniques for analysing biomechanical factors in the specific context of the clinical OA phenotypes. It categorizes preclinical in vivo models into naturally occurring, genetically modified, chemically-induced, surgically-induced, and non-invasive types, linking each to clinical phenotypes like chronic pain, inflammation, and mechanical overload. Specifically, we discriminate between mechanical and biological factors, give a new explanation of the mechanical overload OA phenotype and propose that it should be further subcategorized into two subtypes, post-traumatic and chronic overloading OA. This review then summarises the representative models and tools in biomechanical studies of OA. We highlight and identify how to develop a mechanical model without inflammatory sequelae and how to induce OA without significant experimental trauma and so enable the detection of changes indicative of early-stage OA in the absence of such sequelae. We propose that the most popular post-traumatic OA biomechanical models are not representative of all types of mechanical overloading OA and, in particular, identify a deficiency of current rodent models to represent the chronic overloading OA phenotype without requiring intraarticular surgery. We therefore pinpoint well standardized and reproducible chronic overloading models that are being developed to enable the study of early OA changes in non-trauma related, slowly-progressive OA. In particular, non-invasive models (repetitive small compression loading model and exercise model) and an extra-articular surgical model (osteotomy) are attractive ways to present the chronic natural course of primary OA. Use of these models and quantitative mechanical behaviour tools such as gait analysis and non-invasive imaging techniques show great promise in understanding the mechanical aspects of the onset and progression of OA in the context of chronic knee joint overloading. Further development of these models and the advanced characterisation tools will enable better replication of the human chronic overloading OA phenotype and thus facilitate mechanically-driven clinical questions to be answered.

Osteotomy wedge angle - Aiming to achieve perfection with new device: Pre-clinical stage

Introduction

The surgical execution of osteotomy requires precision in measuring the wedge angle. The pre-operative planning methods are plenty and so are few devices for high tibial osteotomy. But struggle happens for those bony areas other than proximal tibia where alignment correction is needed. The new device is proposed to address this surgical problem. The ease of measuring angle for bony wedge angle, in any bone, independent of its width and in any plane, is the question being solved with the proposed devices.

Methods

Two jig instruments have been shown in the study. First one the curved with direct angle measuring marking in degrees on the body. K wire is accepted through the tower exactly showing the desired angle. The second jig instrument is flat design with marking in millimeters. This device works on trigonometric principle of sum of angles of any triangle is equal to 180°. The jig can be removed leaving the k wires in place to complete the final osteotomy once confirmed.

Results

It's a pre-clinical stage study. The saw bone models show encouraging measurements and perfect execution of angle at the osteotomy site.

Discussion

HTO has been researched a lot with many options of surgical devices. The criticism of using known devices is the variable accuracy, especially for the smaller width of tibial metaphysis. One major limitation of these available instruments is they can be used only for proximal tibial metaphysis. For any other surgical sites like distal femur, distal tibia, distal humerus or tibial slope correction neither these HTO jigs will work nor there is any available universal instrument as such. The common misconception of one degree equal to 1 mm does not stand true at all bony sites. Hence there was a need to solve this problem with universal jig. I have designed two new devices which are currently at pre-clinical stage. The curve device has limitations which get corrected in straight device. The philosophy changes from one direct measurement with two tips of wires forming the angle in a curved device to indirect measurement by simple trigonometric calculation in a straight device. The proposed new device would work in any bone, for any trapezoidal wedge shape osteotomy using simple user-friendly k wires.

High Tibial Osteotomy in Knee Reconstruction and Joint Preservation

High tibial osteotomy is a dynamic operation, used as an effective procedure in both joint preservation and knee stability. Applications and indications are expanding, with good results in the treatment of malalignment associated with arthrosis, knee instability, meniscus deficiency or transplants, and/or cartilage restoration. Appropriate patient selection and preoperative planning are critical to achieving good outcomes after surgery. Coronal and sagittal plane corrections made through the proximal tibia can effectively alter joint mechanics creating a more favorable environment for cartilage, meniscus, and ligamentous structures about the knee. Advancing techniques and technologies have allowed for more precise planning and execution of osteotomies.

Improvement of absorbability, osteoconductivity, and strength of a β-tricalcium phosphate spacer for opening wedge high tibial osteotomy: clinical evaluations with 106 patients

BACKGROUND

An ideal synthetic spacer for medial opening wedge high tibial osteotomy (MOWHTO) has not yet been developed. The authors have developed a new β-tricalcium phosphate (β-TCP) spacer with 60% porosity (N-CP60) by modifying the micro- and macro-pore structures of a conventional β-TCP spacer (CP60) that is widely used in clinical practice. The purpose of this study was to compare the absorbability, osteoconductivity, and in vivo strength of the N-CP60 spacer with those of the CP60 spacer, when used in MOWHTO.

METHODS

First, the porosity, diameter distribution of macro- and micropores, and compressive strength of each β-TCP block were examined using methodology of biomaterial science. Secondly, a clinical study was performed using a total of 106 patients (106 knees) with MOWHTO, who were followed up for 18 months after surgery. In these knees, the N-CP60 and CP-60 spacers were implanted into 49 tibias and 57 tibias, respectively. The absorbability and osteoconductivity were radiologically evaluated by measuring the area of the implanted spacer remaining unabsorbed and assessing with the Hemert's score, respectively. The incidence of cracking in the implanted spacers was determined using computed radiography. Statistical comparisons were made with non-parametric tests. The significance level was set at p = 0.05.

RESULTS

The N-CP60 and CP60 blocks had almost the same porosity (mean, 61.0% and 58.7%, respectively). The diameter of macropores was significantly larger (p < 0.0001) in the N-CP60 block than in the CP60 block, while the diameter of micropores was significantly smaller (p = 0.019) in the N-CP60 block. The ultimate strength of the N-CP60 block (median, 36.8 MPa) was significantly greater (p < 0.01) than that of the CP60 block (31.6 MPa). As for the clinical evaluations, the absorption rate of the N-CP60 spacer at 18 months after implantation (mean, 48.0%) was significantly greater (p < 0.001) than that of the CP60 spacer (29.0%). The osteoconductivity of the N-CP60 spacer was slightly but significantly higher (p = 0.0408) than that of the CP60 spacer only in zone 1. The incidence of in vivo cracking of the posteriorly located N-CP60 spacer at one month (mean, 75.5%) was significantly lower (p = 0.0035) than that of the CP60 spacer (91.2%).

CONCLUSIONS

The absorbability, osteoconductivity, and compressive strength of the new N-CP60 spacer were significantly improved by modifying the macro- and micro-pore structures, compared with the conventional CP60 spacer. The N-CP60 spacer is more clinically useful than the CP60 spacer.

TRIAL REGISTRATION NUMBER

H29-0002.

Vascular injury during lateral close-wedge distal femoral osteotomy: A case report and review of surgical principles

INTRODUCTION

Knee malalignment can increase the risk of osteoarthritis. Osteotomies can correct limb deformities, but they come with the risk of complications such as cortical hinge fracture, hardware failure, pain syndrome, and infection. Vascular injury is rare, but it can lead to bleeding, limb ischemia, and swelling. If revascularization is delayed for over 12 h, it can result in poor outcomes. The work has been reported in line with the SCARE criteria.

CASE

A 41-year-old female underwent a lateral close-wedge distal femoral osteotomy. Postoperatively, no distal pulse was detected. An emergency vascular surgery consultation revealed popliteal vein penetration and popliteal artery thrombosis, probably during pin penetration. Revascularization was performed, and the patient was discharged without complications. At the three-year follow-up, the patient was in good health and without complications.

DISCUSSION

Knowledge of the femoral artery and vein's proximity to the apex of the wedge is crucial in lateral close wedge distal femoral osteotomy. Despite vascular injury with an oscillating saw, it can happen during guide pin insertion. Although Intraoperative massive bleeding can show vascular injury, lack of it was not a protective factor.

CONCLUSION

During the process of pin insertion, it is important to ensure that the pin's orientation is directly lateral to the medial. This should be checked using the C-Arm by obtaining AP, Lat, and Oblique views. To check for intraoperative bleeding, the tourniquet should be deflated. Once the procedure is complete, it is important to check for any vascular injury by examining distal pulses and limb perfusion carefully, particularly in the recovery room.

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.

Unicompartmental osteoarthritis: High survival rate with a combined mechanical and biological salvage approach as alternative to metal resurfacing: Results at minimum 10 years of follow-up

PURPOSE

The aim of this study was to prospectively evaluate the long-term clinical results and failure rate of patients treated with complex salvage procedures using a combined mechanical and biological approach to address unicompartmental knee osteoarthritis (OA) and postpone the need for joint replacement.

METHODS

Thirty-nine patients (40.3 ± 10.9 years old) affected by unicompartmental OA (Kellgren-Lawrence 3) in stable joints underwent a personalized surgical treatment depending on the specific requirements of the affected compartment, including high tibial osteotomy, osteochondral scaffold, meniscal scaffold and meniscal allograft transplantation. Patients were evaluated with the International Knee Documentation Committee (IKDC), Visual Analogue Scale (VAS) and Tegner scores before surgery, at 3 years and a minimum of 10 years of follow-up.

RESULTS

A significant improvement was observed over time in all scores but worsened at the final follow-up. The IKDC subjective score improved from 46.9 ± 16.2 to 79.8 ± 16.4 at 3 years (p < 0.0005) and then decreased to 64.5 ± 21.4 (p = 0.001) at 12 years. A similar trend was confirmed for VAS and Tegner scores. Only two patients subsequently underwent knee arthroplasty, and nine more patients were considered clinical failure, for a cumulative surgical and clinical failure rate of 28.2% at the final follow-up.

CONCLUSION

A personalized, joint-preserving, combined mechanical and biological approach, addressing alignment as well as meniscal and cartilage lesions, is safe and effective, providing a clinical benefit and delaying the need for arthroplasty in young patients affected by unicompartmental knee OA. At the final evaluation, the clinical improvement decreased, but more than two-thirds of the patients still benefited from this treatment at a long-term follow-up.

LEVEL OF EVIDENCE

Level IV case series.

Deformity in valgus knee malalignment is not only in the femur but also in tibia or both, based on demographic and morphological analysis before and after knee osteotomies

PURPOSE

This study aims to identify the demographic and morphological features of valgus knee deformity with unilateral osteoarthritic knee in the coronal plane. A secondary aim was to identify the distinct phenotypes of valgus knees in Hirschmann's phenotype and the coronal plane alignment of the knee (CPAK) classifications before and after a knee osteotomy (KO).

METHODS

A total of 107 patients (57 female and 50 male) with a mean age of 42.4 ± 17.2 years, who underwent varisation osteotomy for symptomatic unilateral knee osteoarthritis (OA) and constitutional valgus deformity, were enrolled in the study, and the mean follow-up period was 29.1 ± 7.3 months. The included cases comprised 60 cases of distal femoral osteotomy, 10 cases of double-level osteotomy and 33 cases of high tibial osteotomy. All patients underwent preoperative and postoperative clinical, functional and radiological evaluations, analysed by analysis of variance tests.

RESULTS

An analysis of the location of the valgus deformities demonstrated that 56 cases (52.3%) were femoral based, 18 cases (16.8%) were both femoral and tibial based and 33 cases (30.9%) were tibial based. Twelve preosteotomy cases (11.2%) and 38 postosteotomy cases (35.5%) matched the most common eight Hirschmann's phenotypes, phenotyping the coronal lower limb alignment based on the native alignment in young patients without OA. Four (3.7%) preosteotomy cases and 89 postosteotomy cases (83.1%) matched the most common three CPAK phenotypes (Ⅰ, Ⅱ, Ⅴ) based on constitutional alignment and joint line obliquity in healthy and osteoarthritic knees.

CONCLUSION

In valgus knee malalignment, the location of the deformity is not only solely femoral-based but also solely tibial-based or combined femoral and tibial-based. An individualised osteotomy approach would be recommended to achieve careful preoperative planning that considers the location of the deformity and the resultant joint line. Hirschmann's and CPAK classification would not be relevant when KO is considered.

LEVEL OF EVIDENCE

Level Ⅳ, retrospective case-control study.

Three-Dimensional Hinge Axis Orientation Contributes to Simultaneous Alignment Correction in All Three Anatomical Planes in Opening-Wedge High Tibial Osteotomy

Purpose

To investigate the simultaneous effect of 3-dimensional (3D) hinge axis (HA) orientation on alignment parameters in all 3 anatomical planes in high tibial osteotomy.

Methods

A computed tomography-based 3D model of a human tibia/fibula was used to establish a 3D tibial coordinate system based on the tibial mechanical axis. In here, an HA was positioned and an opening-wedge high tibial osteotomy with a rotation angle of 10° over the HA was simulated. HA rotation in the axial plane ranged from 0° to 90° and HA tilt relative to the axial plane ranged from -20° to +20°. The study quantified the simultaneous effect of HA orientation on change of alignment parameters in all anatomical reference planes.

Results

HA rotation within the tibial axial plane between orientations perpendicular to the coronal and sagittal planes primarily affected both coronal and sagittal plane alignment, with an inverse relationship between these planes (range: 0°-9.7°); the effect of HA rotation on the change in axial plane alignment was maximally 0.9°. In contrast, HA tilt relative to the tibial axial plane primarily affected axial alignment (maximum change: 6.9°); the effect on change in both coronal and sagittal plane alignment was maximally 0.6°.

Conclusions

HA rotation in the tibial axial plane primarily affects sagittal and coronal plane alignment, and HA tilt relative to the tibial axial plane primarily affects axial plane alignment.

Clinical Relevance

Integrating 3D HA orientation in malalignment planning and correction offers the potential to minimize unintended corrections in nontargeted planes in uniplanar correction osteotomies and to facilitate intentional multiplanar correction with a single osteotomy.

'One millimetre equals one degree' is a major source of inaccuracy in planning osteotomies around the knee for metaphyseal deformities compared to the digital planning

PURPOSE

The objective of this study was to compare the accuracy of virtually performed osteotomies around the knee. The comparison was made between the Miniaci method (method 1), considered the gold standard planning, with the widely held dogma that one degree of correction required equates to one millimetre of opening/closing (method 2).

METHODS

This retrospective cross-sectional study was conducted between December 2018 and September 2022 in patients aged at least 15 years with metaphyseal knee deformity. Osteotomy planning was performed in methods 1 and 2 utilising calibrated long-leg alignment X-rays in the frontal plane. In both methods, the desired correction was defined by the Fujisawa point. The error % in measurement (ratio method 1/method 2) and the difference in millimetres (method 1 - method 2) between the two methods were analysed.

RESULTS

A total of 107 osteotomies with 27 (25.2%) distal femoral osteotomies, 54 (50.5%) proximal tibial osteotomies and 26 (24.3%) double-level osteotomies were performed virtually with a mean hip-knee-ankle angle of 176.4 ± 6.6. In distal femur osteotomy, the mean error % between methods 1 and 2 was 38.9 ± 16.7% and 22.4 ± 16.8% for the opening and closing groups, respectively. In proximal tibial osteotomies, the mean error % was 22.7 ± 15.6% and 9 ± 10.8% for the opening and closing groups, respectively. In double-level osteotomy, the mean error % of femur-based corrections was 34.9 ± 19% and 19.5 ± 21% for the opening and closing groups, respectively, and the mean error of the tibial-based corrections was 26.4 ± 12.1% for the opening group and 10.8 ± 10% for the closing group, respectively.

CONCLUSION

Planning one millimeter per degree of desired correction for osteotomies around the knee in metaphyseal deformities is a major source of error when compared with digital planning using the Miniaci method. This was seen most frequently with osteotomies of the distal femur and all opening wedge osteotomies.

LEVEL OF EVIDENCE

Level Ⅲ, retrospective cross-sectional study.

High survivorship and low complication rate in a single-centre series of 651 medial opening wedge high tibial osteotomy cases with a mean follow-up of 13 years

PURPOSE

This study aimed to report the early to midterm results of medial opening wedge high tibial osteotomy (MOWHTO) from the largest single-centre osteotomy database. The primary outcomes were reporting the radiological corrections and the functional outcomes represented by multiple patient-reported outcome measures (PROMs). The secondary outcomes were to report the complications, revisions and survivorship up to 10 years postoperatively.

METHODS

A prospectively maintained single-centre database of 1138 knee osteotomies was retrospectively reviewed. Patients who underwent MOWHTO and met the inclusion criteria were included. Those inclusion criteria were moderate to severe knee pain that failed conservative management; varus knee malalignment; and isolated medial osteoarthritis of the knee. A total of 651 cases, with a mean age of 46.7 ± 9 years and a mean body mass index of 29.6 ± 5.2 kg/m2 , were included. This comprised 71% males (n = 462) and 29% females (n = 189). The mean follow-up was 158.1 ± 45.4 months. Multiple PROMs were recorded preoperatively and serially postoperatively. This included the Knee injury and Osteoarthritis Outcome Scores, the Oxford Knee Score, the Oxford Knee Score-Activity and Participation Questionnaire, the Western Ontario and McMaster University Scores, the Visual Analogue Scale for health and pain, and the EQ-5D, which is a standardised measure of health-related quality of life. All lower limb alignment measurements were recorded pre- and postoperatively. The rates of osteotomy revision, conversion to arthroplasty, complications, and 5- and 10-year survivorship were recorded.

RESULTS

A total of 651 cases were followed up to a mean of 158.1 ± 45.4 months. The mean planned correction angle was 7.6° ± 2.9°. The mean planned opening wedge distance was 8.1 ± 3.1 mm. The mean intraoperative anterior and posterior osteotomy gaps opening were 7.7 ± 3.4 and 8.9 ± 3.8 mm, respectively. Postoperatively, the mean mechanical tibiofemoral angle improved from -5.7° ± 2.9° varus to 1.3° ± 2.5° valgus, the mean medial proximal tibial angle improved from preoperative 85.5° ± 2.3° to postoperative 91.6° ± 2.7° and the mean Mikulicz point improved from 21.7 ± 12.6% to 54.8 ± 11% (all p values < 0.001). All PROMs significantly improved at 24 months follow-up (all p values < 0.001). The rate of osteotomy revision was 1.1% at a mean of 2 ± 2.5 years postoperatively. The overall rate of arthroplasty conversion was 9.1%. This comprised 5.8% total knee arthroplasty conversion at a mean of 6.9 ± 3.5 years postoperatively and 3.2% unicompartmental knee arthroplasty conversion at a mean of 5.7 ± 2.5 years postoperatively. An overall 10.3% complication rate was recorded. The 5 and 10-year survivorship was 97.2% and 91.9%, respectively.

CONCLUSION

MOWHTO is a radiologically and clinically rewarding procedure with a high survival rate at 5 and 10 years and a low complication rate in experienced hands. MOWHTO should be considered in patients presenting with medial unicompartmental knee pain with an evidence of overload and a varus mechanical coronal plane axis.

LEVEL OF EVIDENCE

Level IV, retrospective cohort study.

Fully automated assessment of the knee alignment on long leg radiographs following corrective knee osteotomies in patients with valgus or varus deformities

INTRODUCTION

The assessment of the knee alignment on long leg radiographs (LLR) postoperative to corrective knee osteotomies (CKOs) is highly dependent on the reader's expertise. Artificial Intelligence (AI) algorithms may help automate and standardise this process. The study aimed to analyse the reliability of an AI-algorithm for the evaluation of LLRs following CKOs.

MATERIALS AND METHODS

In this study, we analysed a validation cohort of 110 postoperative LLRs from 102 patients. All patients underwent CKO, including distal femoral (DFO), high tibial (HTO) and bilevel osteotomies. The agreement between manual measurements and the AI-algorithm was assessed for the mechanical axis deviation (MAD), hip knee ankle angle (HKA), anatomical-mechanical-axis-angle (AMA), joint line convergence angle (JLCA), mechanical lateral proximal femur angle (mLPFA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibia angle (mMPTA) and mechanical lateral distal tibia angle (mLDTA), using the intra-class-correlation (ICC) coefficient between the readers, each reader and the AI and the mean of the manual reads and the AI-algorithm and Bland-Altman Plots between the manual reads and the AI software for the MAD, HKA, mLDFA and mMPTA.

RESULTS

In the validation cohort, the AI software showed excellent agreement with the manual reads (ICC: 0.81-0.99). The agreement between the readers (Inter-rater) showed excellent correlations (ICC: 0.95-0. The mean difference in the DFO group for the MAD, HKA, mLDFA and mMPTA were 0.50 mm, - 0.12°, 0.55° and 0.15°. In the HTO group the mean difference for the MAD, HKA, mLDFA and mMPTA were 0.36 mm, - 0.17°, 0.57° and 0.08°, respectively. Reliable outputs were generated in 95.4% of the validation cohort.

CONCLUSION

 he application of AI-algorithms for the assessment of lower limb alignment on LLRs following CKOs shows reliable and accurate results.

LEVEL OF EVIDENCE

Diagnostic Level III.

Effect of Varus-Producing Distal Femoral Osteotomy and High Tibial Osteotomy on Compartment Pressures and Contact Area at Varying Degrees of Knee Flexion

Background

In patients with valgus alignment and degenerative changes in the lateral compartment, both distal femoral osteotomy (DFO) and high tibial osteotomy (HTO) can be used to unload the lateral compartment. Prior studies have shown that in valgus knees, the tibial wear is posterior and DFO exerts the greatest effect in extension; however, its effect is decreased as flexion angle rises.

Hypothesis

Medial closing-wedge (MCW) HTO would significantly decrease contact area, mean contact pressure (MCP), and peak contact pressure (PCP) in the lateral knee compartment through knee flexion to a greater extent compared with lateral opening-wedge (LOW) DFO.

Study Design

Controlled laboratory study.

Methods

MCWHTO and LOWDFO were performed, correcting a mean of 8° of valgus alignment, in 10 cadaveric knees using plate fixation. Tibiofemoral contact pressure of the medial and lateral compartments was measured in 0°, 30°, 60°, and 90° of knee flexion before and after osteotomy using thin electronic sensors and load applied through an Instron device. PCP, MCP, and contact area were measured for each condition.

Results

The lateral MCP was significantly decreased in the HTO state compared with the native state in 30° (P = .015), 60° (P = .0199), and 90° (P < .0001) of flexion. The lateral MCP was also significantly decreased in the HTO state when compared with the DFO state in 60° (P = .0093) and 90° of flexion (P < .0001). After DFO, the lateral MCP returned to that of the native state in 60° (P > .999) and 90° (P > .999) of flexion. The lateral PCP decreased for all test states in all degrees of flexion; the HTO state was significantly decreased when compared with the native state in 60° (P < .0001) and 90° (P < .0001).

Conclusion

With varus corrections of 8°, MCWHTO was more effective at unloading the lateral compartment than LOWDFO. This effect was significant as the knee flexion angle increased. This study should be considered as one aspect of the surgical decision-making process.

Clinical Relevance

In patients with mild to moderate valgus deformity without hypoplastic lateral femoral condyle and without significant joint line obliquity, MCWHTO may improve offloading of the lateral compartment in flexion.

Complete Correction following Temporary Hemiepiphysiodesis using 2-hole Reconstruction Plates among Skeletally Immature Patients with Angular Deformities around Knees: A Descriptive Cross-sectional Study

INTRODUCTION

Studies have shown that 2-hole reconstruction plates can be used effectively as tension band plates for temporary hemiepiphysiodesis. However, limited data is available regarding the effectiveness of such plates in terms of complete correction rates. This study was aimed to find out the prevalence of complete correction following temporary hemiepiphysiodesis using 2-hole reconstruction plates among skeletally immature patients with angular deformities around knees.

METHODS

A descriptive cross-sectional study was carried out among skeletally immature patients with angular deformities around knees undergoing temporary hemiepiphysiodesis after getting approval from the Institutional Review Committee (Reference number: B&BIRC-23-05). The data were collected between 1 January 2012 to 31 December 2018. All skeletally immature patients with angular deformities around knees undergoing temporary hemiepiphysiodesis using 2-hole reconstruction plates were included. Patients who required additional procedures or implants for deformity correction and those who did not provide consent were excluded. Convenience sampling method was used. Point estimate at 95% Confidence Interval was calculated.

RESULTS

Among 102 patients, 66 (64.70%) patients achieved complete correction (59.97-69.43 at 95% Confidence Interval). Mean age of the patients was 8.21±3.11 years and 43 (65.15%) were males and 23 (34.84%) were females.

CONCLUSIONS

The prevalence of complete correction following temporary hemiepiphysiodesis using 2-hole reconstruction plate among skeletally immature patients with angular deformities around knees was lower than that reported in other international studies.

Osteotomy for treating knee osteoarthritis from 2012 to 2023: Bibliometric analysis and global trends

BACKGROUND

Numerous surgical interventions are available for the treatment of knee osteoarthritis (KOA). In recent years, knee-preserving surgery, specifically osteotomy, has gained significant attention from patients, particularly those who are young and physically active, as it not only effectively alleviates pain but also preserves bone integrity, thereby allowing for potential future joint replacement. This study aims to comprehensively analyze the global application trends of osteotomy for KOA and identify the current research hotspots.

METHODS

We conducted a literature search encompassing English-language studies on osteotomy for KOA published from 2012 to 2023 in the Web of Science Core Collection (WoSCC) database. Bibliometric analysis tools, including VOSviewer, CiteSpace, and R Studio, were employed to analyze global trends and research hotspots.

RESULTS

We analyzed 1520 eligible publications, comprising 1350 articles and 170 reviews. The number of articles on osteotomy for KOA has exhibited a consistent upward trend over the past decade. The top 3 contributing countries (South Korea, United States, and China) accounted for 45.98% of all published articles. U.S. scholars exhibited high productivity, prominence, and academic impact in this field. Seoul National University published the most papers on the relationship between osteotomy and KOA, while Sungkyunkwan University had the highest average citation rate. Among authors, Yong Seuk Lee from Korea and Steffen Schroeter from Germany had the highest number of publications and average citation values, respectively. Research interests were clustered into 5 categories: "High tibial osteotomy," "Biomechanics of osteotomy," "Osteotomy combined with cartilage repair techniques," "Postoperative prognosis and outcomes," and "Improvement of surgical techniques."

CONCLUSION

Recent years have witnessed notable rapid progress in the research on osteotomy for KOA. The field is poised for continued growth in terms of academic literature. The United States has emerged as a global leader in knee osteotomy research, while Korea demonstrates considerable potential in this domain. Future research hotspots may encompass high tibial osteotomies, osteotomies combined with cartilage repair techniques, and advancements in surgical techniques for KOA.

Mixed Reality and Artificial Intelligence: A Holistic Approach to Multimodal Visualization and Extended Interaction in Knee Osteotomy

OBJECTIVE

Recent advancements in augmented reality led to planning and navigation systems for orthopedic surgery. However little is known about mixed reality (MR) in orthopedics. Furthermore, artificial intelligence (AI) has the potential to boost the capabilities of MR by enabling automation and personalization. The purpose of this work is to assess Holoknee prototype, based on AI and MR for multimodal data visualization and surgical planning in knee osteotomy, developed to run on the HoloLens 2 headset.

METHODS

Two preclinical test sessions were performed with 11 participants (eight surgeons, two residents, and one medical student) executing three times six tasks, corresponding to a number of holographic data interactions and preoperative planning steps. At the end of each session, participants answered a questionnaire on user perception and usability.

RESULTS

During the second trial, the participants were faster in all tasks than in the first one, while in the third one, the time of execution decreased only for two tasks ("Patient selection" and "Scrolling through radiograph") with respect to the second attempt, but without statistically significant difference (respectively [Formula: see text] = 0.14 and [Formula: see text] = 0.13, [Formula: see text]). All subjects strongly agreed that MR can be used effectively for surgical training, whereas 10 (90.9%) strongly agreed that it can be used effectively for preoperative planning. Six (54.5%) agreed and two of them (18.2%) strongly agreed that it can be used effectively for intraoperative guidance.

DISCUSSION/CONCLUSION

In this work, we presented Holoknee, the first holistic application of AI and MR for surgical planning for knee osteotomy. It reported promising results on its potential translation to surgical training, preoperative planning, and surgical guidance. Clinical and Translational Impact Statement - Holoknee can be helpful to support surgeons in the preoperative planning of knee osteotomy. It has the potential to impact positively the training of the future generation of residents and aid surgeons in the intraoperative stage.

High tibial osteotomy effectively redistributes compressive knee loads during walking

The objectives of this study were to estimate pre- and postoperative lower limb kinematics and kinetics and knee intra-articular forces during gait using musculoskeletal modeling in a cohort of patients with knee osteoarthritis (OA) undergoing high tibial osteotomy (HTO), compare these to controls, and determine correlations between changes in these parameters and Knee Injury and Osteoarthritis Outcome Score (KOOS) subscores after HTO. Sixteen patients with isolated, symptomatic medial compartment knee OA completed pre- and postoperative gait analysis (mean follow-up time: 8.6 months). Sixteen age- and sex-matched asymptomatic volunteers participated as controls. Musculoskeletal modeling was used to evaluate lower limb joint moments and knee contact forces during gait. While HTO had limited influence on sagittal plane kinematics and moments, significant changes in the load distribution at the knee after HTO were observed with a lower postoperative compressive load on the medial compartment during midstance and a higher compressive load on the lateral compartment during early and late stance. Moreover, the lateral shear force in midstance was significantly lower after HTO. Changes in the external knee adduction moment (KAM) did not always coincide with reductions in the knee compressive force in the medial compartment. Biomechanical changes did not correlate with improvements in KOOS subscores. Hence, HTO effectively unloaded the medial compartment by redistributing part of the overall compressive force to the lateral compartment during gait with limited influence on gait function. The KAM may not adequately describe compartmental load magnitude or changes induced by interventions at the compartment level. Clinical trial registration: ClinicalTrials. gov Identifier-NCT02622204. Clinical significance: This study provides important evidence for changes in joint level loads after corrective osteotomy as joint preserving surgery and emphasizes the need for additional biomechanical outcomes of such interventions.

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.

[High tibial osteotomy with computer navigation for medial gonarthritis]

OBJECTIVE

To study significance of computer navigation for improving clinical and radiological results of medial gonarthritis treatment compared to non-invasive methods of lower limb axis correction control.

MATERIAL AND METHODS

The study included 73 patients who were divided into 2 groups. The main group included 40 patients, the control group - 33 patients. In the main group, high tibial osteotomy was performed using computer navigation, in the control group - using non-invasive techniques. Clinical assessment was carried out according to the KSS, KOOS and VAS scales. We assessed the main reference angles of the lower limb considering X-ray data.

RESULTS

Both groups were characterized by postoperative improvement of clinical results according to various scales. Computer navigation provided higher accuracy in most cases. We focused on target correction of 3° valgus.

CONCLUSION

High tibial osteotomy with computer navigation or non-invasive techniques is an effective treatment method for medial gonarthritis. There are no significant differences in clinical results according to the KSS and KOOS scales, as well as X-ray data after correction. We found significant differences in VAS scores.

Opening- and closing-wedge high tibial osteotomy are comparable and early full weight bearing is safe with angular stable plate fixation: a meta-analysis

PURPOSE

The purpose of this study was to establish the gold standard for surgical technique, fixation, and rehabilitation for HTO in patients with unicompartmental knee osteoarthritis.

METHODS

Medline, Embase, and SPORTDiscus databases were searched up to April 2022. Included were (1) randomized controlled trials (RCTs) comparing opening-wedge HTO (owHTO) and closing-wedge HTO (cwHTO), (2) biomechanical studies and prospective patient studies comparing biomechanical and clinical results for plate fixators, and (3) RCTs comparing an early versus delayed full-weight-bearing (FWB) protocol.

RESULTS

The pooled results for the surgical technique showed no significant differences between owHTO and cwHTO for most PROMs on pain, activity, and risk for conversion to TKA. The cwHTO group showed a slightly better improvement in KOOS/WOMAC pain scores (4.51; 95% CI 1.18-7.85), and a significantly lower change in posterior tibial slope (p = 0.03). The pooled results for the fixation method showed the highest force at maximum failure for the Activmotion (Newclip Technics, France), Aescula (B. Braun Korea, Korea), 2nd generation Puddu (Arthrex Inc., USA), and TomoFix plate (Depuy Synthes, Switzerland). The pooled results for the rehabilitation protocol showed no significant differences between the early full-weight-bearing (FWB) group and the delayed FWB group for functional scores, complication rates, and delayed unions.

CONCLUSION

Both owHTO and cwHTO reduced pain and improved knee function. Locking plate fixation should be used for owHTO. An early FWB protocol has proven to be safe in patients with small corrections, no hinge fractures, and non-smokers.

LEVEL OF EVIDENCE

Level II.

Risk Factors Affecting Return to Sports and Patient-Reported Outcomes After Opening-Wedge High Tibial Osteotomy in Active Patients

Background:

Although opening-wedge high tibial osteotomy (OWHTO) is favored for active patients who expect to return to sports, there is still a lack of robust evidence for factors affecting their recovery.

Purpose:

To identify (1) risk factors leading to a decreased level of return to preoperative sports after OWHTO and (2) patient characteristics and intraoperative factors influencing patient-reported outcomes after return to sports.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

Included were 69 patients who underwent OWHTO and who expected to return to their preoperative level of sports, measured as a Tegner activity level ≥2. All included patients had a minimum of 1 year of follow-up data. Logistic regression analyses were performed to assess the effect of independent variables on the level of return to preoperative sports after surgery; the independent variables were age, sex, body mass index, preoperative Tegner score, preoperative Kellgren-Lawrence grade, preoperative percentage of mechanical axis (%MA), opening gap width, concomitant meniscal treatment, postoperative %MA, postoperative medial proximal tibial angle (MPTA), and postoperative posterior tibial slope. Univariate and multiple regression analyses were performed to assess for influencing factors on postoperative International Knee Documentation Committee (IKDC) subjective scores in patients who were able to return to sports.

Results:

Of the 69 patients, 51 (73.9%) returned to sports after OWHTO. High preoperative Tegner scores were statistically associated with a decrease in return to sports (odds ratio, 1.494; P = .033). Multiple regression analysis (n = 46 patients) identified that a higher postoperative MPTA was associated with a decreased IKDC subjective score after return to sports (r = –0.345; P = .019).

Conclusion:

Higher postoperative MPTA was associated with the worsening of patient-reported outcomes among those patients who did return to their preoperative sports after OWHTO. Also, participation in high-activity sports was confirmed to be a significant risk factor for a decreased rate of return to preoperative sports. These findings can support preoperative planning and intraoperative decision making, particularly for active patients.

Osteotomies and Total Knee Arthroplasty: Systematic Review and Meta-Analysis

Total knee replacement (TKA) is a frequent modality performed in patients with osteoarthritis. Specific circumstances can make it much more difficult to execute successfully, and additional procedures such as osteotomy may be required. The aim of this study was to perform a meta-analysis and systematic review of osteotomies combined with TKA.

METHODS

In June 2022, a search PubMed, Embase, Cochrane, and Clinicaltrials was undertaken, adhering to PRISMA guidelines. The search included the terms "osteotomy" and "total knee arthroplasty".

RESULTS

Two subgroups (tibial tubercle osteotomy and medial femoral condyle osteotomy) were included in the meta-analysis. Further subgroups were described as a narrative review. The primary outcome showed no significant difference in favor to TTO. Secondary outcomes showed improved results in all presented subgroups compared to preoperative status.

CONCLUSION

This study showed a significant deficit of randomized control trials treated with osteotomies, in addition to TKA, and a lack of evidence-based surgical guidelines for the treatment of patients with OA in special conditions: posttraumatic deformities, stiff knee, severe varus, and valgus axis or patella disorders.

Surgeons' expectations of osteotomies around the knee

INTRODUCTION

High tibial osteotomy (HTO) is a valid and joint preserving surgical technique to treat medial degenerative osteoarthritis (OA) in young and active patients. A recent study shows that patients' expectations of osteotomy around the knee are high, but OA progression and potential conversion to a total knee arthroplasty (TKA) were underestimated. The aim of this study was to investigate surgeons' expectations of HTO and to compare the results to the patients' expectations and actual outcomes reported in the literature.

METHODS

461 surgeons were questioned online using the 'Hospital for Special Surgery Knee Surgery Expectations Survey (HFSS-KSES)' and a ten-item non-validated questionnaire to investigate the expectations of HTO. Two subgroups were formed to investigate differences regarding the surgeons' experience. Statistical analysis was performed using IBM SPSS Statistics.

RESULTS

Surgeons' expectations of HTO were rated between very and little important with pain reduction being the most important item on the HFSS-KSES. Furthermore, 'improving the ability to walk', 'to perform daily activities', 'having confidence in the knee', and 'avoiding future degeneration' were rated of high importance. An important difference regarding the experience was the lower expectations on delay/prevention of TKA of less-experienced surgeons.

CONCLUSION

Surgeons' expectations of HTO are high but nevertheless different to the patients' expectations reported in the literature. Also, expectations for the delay/prevention of TKA differed regarding the experience of surgeons. While pain reduction represents one of the most important items for surgeons and patients, the expected outcome regarding the delay/prevention of a TKA and returning to sports differs to the patients' expectations and to the actual outcome reported in the literature. This should be considered when performing the preoperative informed consent.

Minimally Invasive Double Level Osteotomy in Severe Knee Varus: Pearls and Pitfalls

Minimally invasive double-level osteotomy (DLP) surgery is performed in severe knee varus, when extra-articular deformity is identified in both the distal femur and proximal tibia. The main advantage is to maintain a horizontal joint line and avoid creating secondary anatomic deformities. This article considers the pearls and pitfalls in performing minimally invasive DLO surgery.

Coronal plane deformity around the knee in the skeletally immature population: A review of principles of evaluation and treatment

Coronal plane deformity around the knee, also known as genu varum or genu valgum, is a common finding in clinical practice for pediatricians and orthopedists. These deformities can be physiological or pathological. If untreated, pathological deformities can lead to abnormal joint loading and a consequent risk of premature osteoarthritis. The aim of this review is to provide a framework for the diagnosis and management of genu varum and genu valgum in skeletally immature patients.

A review of role of osteotomy in knee ligament injuries

Realignment osteotomies around the knee joint are used primarily for management of arthritis. Traditionally, an unstable knee has been considered a contraindication for osteotomy. But with a better understanding of biomechanics of osteotomies and their effect on ligament instabilities, the beneficial role of osteotomies in managing an unstable knee is becoming clearer. This review looks at recent literature on this subject to help in formulating a management plan especially in failed ligament reconstruction patients.

Is the lateral tibial spine a reliable landmark for planning tibial or femoral valgus osteotomies?

INTRODUCTION

A valgus osteotomy around the knee is a conservative procedure performed to unload the medial tibiofemoral compartment. However, the optimal postoperative alignment target remains controversial. Many studies have applied a "Fujisawa point" at 62.5%. The results of recent studies suggest decreasing the range of the mechanical axis target correction to 50-55%. The primary purpose of this study was to define the mean position of the lateral tibial spine in healthy patients from a reproducible 3-dimensional (3D) analysis. The study hypothesis was that the apex of the lateral tibial spine was a reliable and reproducible landmark for planning valgus osteotomies and preventing overcorrections.

MATERIALS AND METHODS

The study included 1140 patients: 560 women and 580 men, with a mean age of 61.7±16.5 years (18-98) and a mean body mass index (BMI) of 24.9±4.9kg/m² (13.3-54.6). This analysis was done with the Stryker Orthopaedics Modeling and Analytics (SOMA) system which uses a database of computed tomography (CT) scans and 3D bone models. A statistical assessment was performed to determine the mean position of the lateral tibial spine. These measurements were then compared according to ethnicity, sex, age, BMI, knee side (right and left) and the overall mechanical axis of the leg.

RESULTS

The mean tibial plateau width was 72.9±5.7mm (59.1-91.1). The mean position of the lateral tibial spine was 53.6±1.1% (48.9-57.2). The mean position of the medial tibial spine was 48.4±2.5% (43.6-56.1) while the center of the tibial spines was 51.0±1.5% (46.4-56.1). Africans had a significantly more lateral mean tibial spine position than Asians (54.7% vs. 53.3%, p=0.001), Caucasians (54.7% vs. 53.7%, p=0.002) and Middle Easterners (54.7% vs. 53.6%, p=0.034).

CONCLUSION

The lateral tibial spine is a simple and reproducible bony landmark. This landmark can be used when planning valgus osteotomies aiming for a "Fujisawa point" at 54%.

LEVEL OF EVIDENCE

IV.

Insufficient Correction and Preoperative Medial Tightness Increases the Risk of Varus Recurrence in Open-Wedge High Tibial Osteotomy

PURPOSE

To assess serial changes of limb alignment after open wedge high tibial osteotomy (HTO) using the weightbearing line (WBL) ratio in the midterm, with a focus on varus recurrence.

METHODS

Patients undergoing open wedge HTO from January 2010 to December 2016 were retrospectively reviewed. Those without serial postoperative weightbearing long-leg alignment films, those who showed remained varus alignment after osteotomy, and those who had <2 years of follow-up were excluded. In terms of immediate postoperative limb alignment (≤3 months) measured using WBL ratio, cases were categorized into 4 groups: <50%, undercorrection; 50% to 57%, insufficient correction; 57% to 67%, planned correction; and >67%, overcorrection. To determine risk factors for varus recurrence (WBL ratio <50%), immediate postoperative WBL ratio category and preoperative valgus and varus stress angles (which represent medial and lateral tightness of the joint, respectively) were investigated using logistic regression analysis, taking other related factors into account. Clinical outcomes according to varus recurrence were measured using Hospital for Special Surgery (HSS) scores.

RESULTS

A total of 148 cases were included. Varus recurrence was noted in 40 cases (27.0%), with a mean follow-up of 49.7 ± 21.8 months (range 24 to 102 months). The incidence of varus recurrence was different according to WBL ratio category: 10/10 (100.0%) in undercorrection; 16/33 (48.5%) in insufficient correction; 13/58 (22.4%) in planned correction; and 1/47 (2.1%) in overcorrection. Based on logistic regression analysis, insufficient correction and preoperative valgus stress angle were found to be significant risk factors (P = .038, and .008, respectively). With valgus stress angle <2°, 7 of 10 insufficient correction cases showed varus recurrence (P = .005). However, HSS scores did not differ according to varus recurrence (P = .363).

CONCLUSION

Insufficient correction and preoperative medial tightness increased the risk of varus recurrence. Especially in cases where preoperative valgus stress angle was <2°, insufficient correction was strongly associated with varus recurrence. However, no significant differences in clinical outcomes were observed according to varus recurrence in the midterm.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Return to sport following distal femur osteotomy: a systematic review

INTRODUCTION

Distal femur osteotomies (DFOs) are well-accepted procedures in treating unicompartmental knee osteoarthritis associated with valgus malalignment. This study aims to investigate the Return to sport (RTS) after DFO.

MATERIALS AND METHODS

We conducted a systematic review of the literature according to the PRISMA guidelines, including all articles published in English, with no time limit, excluding double-level knee osteotomies.

RESULTS

Five articles were included for an overall cohort of 76 patients. The mean follow-up was 45.53 months. The mean age of the patients at the time of surgery was 33.87 years, and the mean malalignment was 5.59° in valgus. In 70 cases, patients received a lateral DFO, while in 6 cases, a medial closing-wedge DFO. An RTS of 86.1% was observed after DFO and a mean time to RTS of 12.3 months. 76.8% of patients recovered to a level equal to or higher than that practiced before the onset of symptoms. No statistically significant differences were observed in the RTS rate between those who performed lateral or medial DFO.

CONCLUSIONS

RTS after DFO is ubiquitous and occurs around one year after surgery. In most cases, patients report improved performance compared to what they experienced before the onset of symptoms. Unfortunately, while athletes often have RTS at a similar or better level, other patients often see a return to lower impact sports.

Gait analysis and knee joint kinematics before a and 6 month after of corrective valgus osteotomy at patients with medial knee arthritis

PURPOSE

A varus deformity (VD) of the lower limbs results in greater loading of the medial compartment of the knee joint (KJ), leading to its degenerative changes and, eventually, to progressive osteoarthritis (OA) of the joint. The aim of the study was to investigate the mid-term changes in gait biomechanics and clinical symptoms in patients with VD of KJ and OA before and six months after surgical correction.

METHODS

The study enrolled 25 patients with medial OA of grade 2-3 according to Kellgren-Lawrence and a VD of > 3°, who underwent arthroscopic lavage and debridement of the knee joint followed by corrective osteotomy. The control group included 20 healthy adults. Clinical and biomechanical assessments were done twice: immediately prior to and six months after the surgical treatment. Biomechanical parameters of gait were recorded using an inertial sensor system.

RESULTS

According to our findings, there was a statistically significant post-operative increase in the knee extension amplitude by 1.4° in female patients and an insignificant extension increase in male patients. The mean postoperative KOOS score was 66.7 points (46 to 91) in the patient group, 67.1 points (54 to 91) in males, and 59.5 points (46 to 64) in females. As early as six months after a valgus osteotomy, we already observed improved biomechanics of the KJ motions compared to pre-operative data. By that time, the swing flexion amplitude of the affected KJ had increased and became symmetrical, which had not been the case before surgery. We observed a total of three changes in the KJ kinematics after surgery: increased swing flexion amplitudes in both KJs, a decreased extension amplitude in the affected KJ, and increased first flexion amplitudes in both KJs.

CONCLUSION

According to our study, the midterm outcomes after a valgus osteotomy showed clinical improvements based on the VAS and KOOS scores, which were however less pronounced than in similar studies with a longer assessment term after surgery. We also found a significant increase in the amplitude of joint extension, but only in females. As the function of the operated joint is concerned, valgus osteotomy restored the kinematics of walking movements to a nearly normal gait with increased first and second flexion amplitudes. The function of KJ becomes symmetric though the non-operative side. Thus, the healthy and functionally more capable side is copying the movement pattern of the affected side. Hence, the non-operative leg is functioning less efficiently than it is required by the walking pace.

The 3-triangle method preserves the posterior tibial slope during high tibial valgus osteotomy: first preliminary data using a mathematical model

PURPOSE

Despite much improved preoperative planning techniques accurate intraoperative assessment of the high tibial valgus osteotomy (HTO) remains challenging and often results in coronal over- and under-corrections as well as unintended changes of the posterior tibial slope. Noyes et al. reported a novel method for accurate intraoperative coronal and sagittal alignment correction based on a three-dimensional mathematical model. This is the first study examining preliminary data via the proposed Noyes approach for accurate intraoperative coronal and sagittal alignment correction during HTO.

METHODS

From 2016 to 2020 a total of 24 patients (27 knees) underwent HTO applying the proposed Noyes method (Noyes-Group). Radiographic data was analyzed retrospectively and matched to patients that underwent HTO using the conventional method, i.e., gradual medial opening using a bone spreader under fluoroscopic control (Conventional-Group). All operative procedures were performed by an experienced surgeon at a single orthopaedic university center.

RESULTS

From the preoperative to the postoperative visit no statistically significant changes of the posterior tibial slope were noted in the Noyes-Group compared to a significant increase in the Conventional-Group (p = 0.01). Regarding the axial alignment no significant differences between both groups were observed pre- and postoperatively. The number of over- and under-corrections did not differ significantly between both groups. Linear regression analysis showed a significant correlation of the postoperative medial proximal tibial angle (MPTA) with the position of the weightbearing line on the tibial plateau.

CONCLUSION

The 3-triangle method by Noyes seems to be a promising approach for preservation of the posterior tibial slope during HTO.

Preoperative Planning and Preservation of the Knee with Complex Osteotomies

The knee is a complex structure composed of bone, cartilage, menisci, ligaments and muscles, which all work synergistically to optimize congruence, stability, and function. Osteotomies are procedures addressing an abnormal joint alignment, shifting the mechanical load from a diseased joint compartment to a healthier one. Preoperative planning is an important art of identifying the source of abnormal load distribution to the joint, enabling the surgeon to simulate a deformity correction ahead of the surgical procedure.

[Clinical and functional outcomes of valgus osteotomy in patients with medial gonarthrosis (preliminary results)]

OBJECTIVE

To analyze gait biomechanics before and after corrective osteotomies around the knee joint in patients with medial gonarthrosis.

MATERIAL AND METHODS

The study recruited 5 patients (6 surgeries) with medial gonartrosis and varus knee deformity. Gait biomechanics was analyzed in preoperative period and 6 months later. The control group consisted of 20 healthy people.

RESULTS

Knee joint biomechanics was almost normal in postoperative period. Amplitude of knee joint flexion was increased. Moreover, hip joint flexion-extension amplitude was increased on both sides and often exceeded normal values. Clinical results showed significant increase in IKS (from 55 to 89.6) and VAS score (from 7.7 to 2.3). Postoperative correction angle varied within 1.5-2° of valgus.

CONCLUSION

Corrective osteotomy around the knee joint is effective for medial gonarthrosis. We obtained favorable clinical results and limb axis correction after surgery without significant hypercorrection. Gait biomechanics was also improved.

High Tibial Osteotomies for the Treatment of Osteoarthritis of the Knee

»

A high tibial osteotomy (HTO) is a joint-preserving procedure that can be used to treat symptomatic unicompartmental cartilage disorders in the presence of limb malalignment.

»

Appropriate patient selection and careful preoperative planning are vital for optimizing outcomes.

»

Based on past literature, correction of varus malalignment to 3° to 8° of valgus appears to lead to favorable results. Recently, there has been growing awareness that it is important to consider soft-tissue laxity during preoperative planning.

»

Although there has been a recent trend toward performing opening-wedge rather than closing-wedge or dome HTOs for unicompartmental osteoarthritis, current data suggest that all 3 are acceptable techniques with varying complication profiles.

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Based on current evidence, an HTO provides pain relief, functional improvement, and a high rate of return to sport, with reported survivorship ranging from 74.7% to 97.6% and 66.0% to 90.4% at 10 and 15 years, respectively.

Increased patellar bone tracer uptake in preoperative SPECT/CT before medial opening high tibial osteotomy correlates with inferior clinical outcome

PURPOSE

The purpose of this study was to investigate whether specific bone tracer uptake (BTU) patterns on preoperative SPECT/CT could predict which patients with varus alignment and medial overload would particularly benefit from medial opening-wedge high tibial osteotomy (MOWHTO). It was the hypothesis that an increased preoperative BTU relative to the reference BTU of the femur on SPECT/CT in the lateral and patellar compartments of the knee are predictive factors for inferior clinical outcome and that the clinical outcome correlates with the extent of alignment correction.

METHODS

Twenty-three knees from 22 patients who underwent MOWHTO for medial compartment overload were investigated preoperatively using Tc-99m-SPECT/CT. BTU was quantified and localised to specific joint areas according to a previously validated scheme. Pre- and postoperative mechanical alignment was measured. Clinical outcome was assessed at a median of 24 months (range 11-30) after MOWHTO by collecting the WOMAC score.

RESULTS

Significant correlations between BTU in the patellar area and the total WOMAC score and its subcategories pain and stiffness were found. Thus, BTU in the 1sPat area (superior lateral patellar compartment) correlated with total WOMAC (rho = 0.43, p = 0.04), pain subcategory (rho = 0.43, p = 0.04), and stiffness subcategory (rho = 0.59, p = 0.003). No significant correlations were found between alignment correction, age, gender and WOMAC.

CONCLUSION

This study highlights the role of preoperative SPECT in modern knee surgery to obtain information about the loading pattern on different compartments of the knee. Despite the limited number of participants, the present study shows that a preoperative SPECT/CT scan can help the treating surgeons to identify patients who may be at risk of inferior clinical outcome if an MOWHTO is considered, as an elevated BTU in the patellar region on preoperative SPECT/CT appears to be a potential risk factor for postoperative pain and stiffness.

LEVEL OF EVIDENCE

Level III.

Prior high tibial osteotomy is not a contraindication for medial unicompartmental knee arthroplasty

PURPOSE

To report on the outcome and complications of minimal invasive medial unicondylar knee arthroplasty (UKA) after failed prior high tibial osteotomy (HTO) as treatment for medial osteoarthritis in the knee. The hypothesis was that good results can be achieved, if no excessive postoperative valgus alignment and abnormal proximal tibial geometry is present.

METHODS

All medial UKAs after failed prior HTO (n = 30), performed between 2010 and 2018 were retrospectively reviewed. The patients were followed for revision surgery and survival of the UKA (defined as revision to TKA). Clinical examination using the Knee Society Score (KSS), Oxford Knee Score (OKS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), as well as radiological examination was performed. Radiographs were studied and the influence of the demographic factors and the radiographic measurements on the survival and the clinical outcome was analysed.

RESULTS

After a follow-up of 4.3 ± 2.6 years (2.1-9.9) 27 UKAs were available. The survival rate was 93.0%. Two UKAs were revised to TKA (excessive valgus alignment and tibial loosening with femoropatellar degeneration). Two further patients had revision surgery (hematoma and lateral meniscus tear). Follow-up clinical and radiological examination was performed in 21 cases: KSS 82.9 ± 10.1 (54.0-100.0), KSS (function) 93.3 ± 9.7 (70.0-100.0); OKS 42.7 ± 6.0 (25.0-48.0); WOMAC 7.9 ± 15.6 (0.0-67.1). No significant influence of demographic factors or radiological measurements on the clinical outcome was present.

CONCLUSION

Prior HTO is not a contraindication for medial UKA, because good-to-excellent results can be achieved in selected patients with medial osteoarthritis and previous HTO, treated with medial UKA, in a midterm follow-up. Excessive mechanical valgus axis should be avoided; therefore, patient selection and accurate evaluation of medial laxity, preoperative mechanical axis, joint line convergence and proximal tibial geometry are important.

LEVEL OF EVIDENCE

III.

The difficulty of continuing sports activities after open-wedge high tibial osteotomy in patient with medial knee osteoarthritis: a retrospective case series at 2-year-minimum follow-up

Purpose

This study aimed to investigate the rate at which patients returned to sports after open wedge high tibial osteotomy and identify the continuity of sports activity post-operatively.

Methods

Thirty-five patients (40 knees) who underwent open-wedge high tibial osteotomy (OW-HTO) in medial knee osteoarthritis were included in this study. The mean age of the patients who underwent surgery was 55.1 ± 10.7 years, and the mean follow-up period was 41.0 ± 24.7 months. Clinical results and radiographic parameters calculated in standing whole-leg radiographs preoperatively, post-operatively, and at the final follow-up were evaluated.

Results

Thirty-one patients (88.6%) were able to return to preoperative sports activity; however, only 14 patients (40.0%) completely returned to preoperative sports activity levels. Of the 31 patients who returned to sports activity, 10 patients (32.3%) maintained post-operative sporting activity levels at the final follow-up. In radiographic parameters, the weight-bearing line ratio was considered loss of correction in the post-operative period leading to the final follow-up. Patients who completely returned to sports and maintained sporting activity levels at the final follow-up had significantly higher the Knee Injury and Osteoarthritis Outcome Score pain subscale values and lower visual analogue scale of knee pain at pre-surgery and final follow-up than other patients, including those who partially returned to sports.

Conclusions

The proportion of patients who returned to sports after OW-HTO and were able to participate in competitions at the same activity level as before surgery was low and insufficient.

Level of evidence

Retrospective case series, IV

Resident Involvement in Posterior Lumbar Interbody Fusion is Associated With Increased Readmissions and Operative Time, But No Increased Short-term Risks

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

The aim was to compare rates of adverse events and additional posterior lumbar interbody fusion (PLIF) cases assisted by residents versus cases performed solely by an orthopedic attending.

SUMMARY OF BACKGROUND DATA

PLIF is a widely accepted surgical technique for the management of a variety of spinal conditions requiring spinal stabilization and fusion. However, no published studies have assessed the effects of resident involvement on intraoperative and postoperative outcomes in PLIF.

METHODS

This retrospective study utilized the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) registry from 2007 to 2012 to identify patients who underwent PLIF procedures. A propensity score matching model was utilized to reduce patient cohort variances. The perioperative data and outcomes in the matched population were analyzed using paired t test and the McNemar test in order to assess, based on resident presence, the rates of postoperative adverse events, readmission, reoperation within 30 days, and operative time.

RESULTS

In total, 1633 patients undergoing PLIF were included in the study, with 24.62% involving resident participation. The propensity score matching algorithm yielded 396 well-matched resident and nonresident pairs. Patients undergoing PLIF involving a resident were associated with a higher rate of readmission (1.77% vs. 0.00%; P=0.008), and longer operative time (245.7 vs. 197.7 min; P<0.001). However, these procedures were not associated with any significant difference in minor or severe adverse events.

CONCLUSIONS

Resident involvement in PLIF was associated with an increased rate of readmissions, and operative time; however, was not associated with an increase in minor or severe adverse events. Further investigation is needed to characterize the role of resident involvement based on level of training experience, as well as methods to improve the learning curve to independence while reducing postoperative hospital length of stay.

LEVEL OF EVIDENCE

Level III-retrospective comparative study.

Towards planning of osteotomy around the knee with quantitative inclusion of the adduction moment: a biomechanical approach

PURPOSE

Despite practised for decades, the planning of osteotomy around the knee, commonly using the Mikulicz-Line, is only empirically based, clinical outcome inconsistent and the target angle still controversial. A better target than the angle of frontal-plane static leg alignment might be the external frontal-plane lever arm (EFL) of the knee adduction moment. Hypothetically assessable from frontal-plane-radiograph skeleton dimensions, it might depend on the leg-alignment angle, the hip-centre-to-hip-centre distance, the femur- and tibia-length.

METHODS

The target EFL to achieve a medial compartment force ratio of 50% during level-walking was identified by relating in-vivo-measurement data of knee-internal loads from nine subjects with instrumented prostheses to the same subjects' EFLs computed from frontal-plane skeleton dimensions. Adduction moments derived from these calculated EFLs were compared to the subjects' adduction moments measured during gait analysis.

RESULTS

Highly significant relationships (0.88 ≤ R2 ≤ 0.90) were found for both the peak adduction moment measured during gait analysis and the medial compartment force ratio measured in vivo to EFL calculated from frontal-plane skeleton dimensions. Both correlations exceed the respective correlations with the leg alignment angle, EFL even predicts the adduction moment's first peak. The guideline EFL for planning osteotomy was identified to 0.349 times the epicondyle distance, hence deducing formulas for individualized target angles and Mikulicz-Line positions based on full-leg radiograph skeleton dimensions. Applied to realistic skeleton geometries, widespread results explain the inconsistency regarding correction recommendations, whereas results for average geometries exactly meet the most-consented "Fujisawa-Point".

CONCLUSION

Osteotomy outcome might be improved by planning re-alignment based on the provided formulas exploiting full-leg-radiograph skeleton dimensions.

Photobiomodulation as an Adjunctive Treatment to Physiotherapy for Reduction of Anterior Knee Pain in Combat Soldiers: A Prospective, Double-Blind, Randomized, Pragmatic, Sham-Controlled Trial

BACKGROUND AND OBJECTIVES

Anterior knee pain (AKP) is the most common knee pathology in athletes and occurs in 15% of army recruits of elite units during basic training. Of these, 50% are symptomatic 6 years later. Photobiomodulation (PBM) is a nonthermal red-to-near-infrared irradiation used for pain reduction of a variety of etiologies. This study was designed to determine whether addition of PBM to physiotherapy (PT) for AKP in combat soldiers is superior to PT alone.

STUDY DESIGN/MATERIALS AND METHODS

In this prospective, double-blind, sham-controlled, randomized clinical trial (NCT02845869), 26 combat soldiers/policemen (male:female, 15:11; body mass index [BMI] = 24.2 ± 3.9, n = 46 knees), with AKP due to overuse/load, received 4 weeks of PT + sham (PT + Sham) or active PBM (wavelength = 660 and 850 nm, pulsing = 2.5 Hz, LED power = 50 mW/cm² [local tissue/regional lymph nodes]; 810 nm continuous beam, laser cluster 6 W/cm² [analgesia] and laser pointer 4.75 W/cm² [trigger points]) (PT + PBM). The main outcome measures were subjective pain by visual analog scale (VAS) (0 [none]-100 [intolerable]) and functional disability by Kujala score (0 [worst]-100 [best]). Evaluations were carried out at baseline, end of treatments, and 3-month follow-up.

RESULTS

All participants completed the treatment protocol without any reported adverse device effects. Post-treatment pain was significantly reduced in the PT+PBM group, compared with baseline and sham (Δpain, VAS, mean ± SD: PT + PBM = -19 ± 23, P = 0.002; PT + Sham = -6 ± 21, P = 0.16; between groups, P = 0.032). At 3-month follow-up, pain reduction was similar between groups; however, the Kujala score was significantly improved only in the PBM-treated group (ΔKujala: PT + PBM = 11 ± 10, P = 0.003; PT + Sham = 5 ± 7, P = 0.059).

CONCLUSIONS

Addition of PBM to PT for AKP resulted in earlier reduction in pain and improved functionality, compared with PT alone. This noninvasive, nonpharmacologic, adjunctive therapeutic modality can be easily incorporated into team healthcare frameworks or end units and may lead to earlier return to competition or combat-level service. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Change in leg length after open-wedge high tibial osteotomy can be predicted from the opening width: A three-dimensional analysis

BACKGROUND

The purpose of this study was to evaluate true change in leg length after open-wedge high tibial osteotomy (OWHTO) using three-dimensional (3D) assessments, examine the factors that influence leg lengthening and verify their validity in clinical practice.

METHODS

Study 1: a retrospective case series simulation study, included 46 patients (55 knees) that underwent knee arthroplasty or HTO. OWHTO was simulated from preoperative computed tomography using 3D preoperative planning software. Uni- and multivariate regression analyses were conducted to identify predictors related to change in leg length. Study 2: a retrospective case series study, included 53 patients (55 knees) that underwent OWHTO in another institution. Change in leg length was measured preoperatively and 1 year postoperatively and was compared with the predicted change in leg length calculated using the formula obtained from Study 1.

RESULTS

Study 1: the true change in leg length significantly increased and showed a strong correlation with the opening width. The change in leg length was predicted using the formula "change in leg length = opening width × 0.75-1.5." Study 2: the predicted change in leg length showed no significant difference from the change in leg length 1 year postoperatively and a strong correlation with the measured change.

CONCLUSIONS

The true change in leg length after OWHTO was predicted using the formula obtained from the 3D model. Predicting the change in leg length preoperatively can be a basis to consider other HTOs.

Return to sports rate after opening wedge high tibial osteotomy in athletes

PURPOSE

We hypothesized that patient treated with OWHTO who participate in high-impact sports would attain satisfactory outcome. The purpose of this study was to examine the clinical and radiological outcomes in a consecutive series of opening-wedge high tibial osteotomy (OWHTO) in highly active patients.

METHODS

Seventy-seven consecutive patients who underwent OWHTO with varus osteoarthritic knees were included in the study. The mean age of the study population was 56.1 years. All patients were followed for a minimum of 2 years. Clinical and radiological evaluations were performed at 12 and 24 months after surgery. The clinical results were evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee (IKDC) Subjective Score. In regards to radiological assessment, the following parameters were measured in full-length weightbearing radiographs both pre- and postoperatively; mechanical tibiofemoral angle (mTFA), mechanical lateral distal femoral angle (mLDFA), and weight bearing line (WBL) ratio.

RESULTS

Fifty-eight patients (75.3%) returned to the same high-impact sports activities as before surgery, with a mean time to return of 8.7 ± 2.7 months (6-14 months). In the clinical assessments, the IKDC subjective score and KOOS both improved from the mean preoperative scores of 38.4 and 217.4 points to the mean postoperative scores of 74.5 and 421.6 points, respectively. The mean pre-symptomatic Tegner activity scale was 5.3 ± 0.6 and significantly decreased to 4.8 ± 1.2 at 2 years postoperative (p < 0.05). In the radiological evaluation, the postoperative mTFA, mMPTA, and WBL ratio values averaged 1.3° ± 2.2° valgus, 90.7° ± 2.9°, and 51.6% ± 8.4°, respectively, at 24 months after surgery.

CONCLUSIONS

Clinical outcomes based on postoperative patient-reported outcome measures and rate of return to high-impact sports activities were favorable after OWHTO in patients with knee OA who desired to continue sporting activities with the Tegner activity score of  ≥ 5 points.

LEVEL OF EVIDENCE

Retrospective case series, IV.

Editorial Commentary: High Tibial Osteotomy Is Effective, Even in Patients With Severe Osteoarthritis: Contradiction of Another Dogma From the Past

High tibial osteotomy is a widespread treatment option and has been performed in the treatment of osteoarthritis long before joint replacements started their triumphant era in the last third of the last century. However, osteotomies have again gained increased interest and popularity within the last 2 decades. Historically, osteotomies have mainly been recommended for early osteoarthritis and contraindicated for advanced osteoarthritis. However, over time, some historic but widespread dogmas have already been contradicted regarding high tibial osteotomy. Osteotomies are very well possible and can yield excellent outcomes, even in patients with severe osteoarthritis. Thus, another dogma from the past is contradicted.

A supplemental screw enhances the biomechanical stability in medial open-wedge high tibial osteotomy

Background

The supplemental screw technique was introduced for salvage of lateral hinge fracture in medial open-wedge high tibial osteotomy (owHTO). The efficacy of its use in protection of lateral hinge fracture and corresponding biomechanical behaviors remained unclear. The current study was aimed to clarify if a supplemental screw can provide better protection to lateral hinge in biomechanical perspective.

Materials

An in vitro biomechanical test was conducted. Tibial sawbones, commercial owHTO plates and a cannulated screw were utilized for preparing the intact, owHTO, and owHTO with cannulated screw insertion specimens. A “staircase” dynamic load protocol was adopted for axial compressive test with increasing load levels to determine structural strength and durability by using a material testing system, while a motion capture system was applied for determining the dynamic changes in varus angle and posterior slope of the tibia plateau with various specimen preparation conditions.

Results

Type II lateral hinge fracture were the major failure pattern in all specimens prepared with owHTO. The insertion of a supplemental cannulated screw in medial owHTO specimens reinforced structural stability and durability in dynamic cyclic loading tests: the compressive stiffness increased to 58.9–62.2% of an intact specimen, whereas the owHTO specimens provided only 23.7–29.2% of stiffness of an intact specimen. In view of tibial plateau alignment, the insertion of a supplemental screw improved the structural deficiency caused by owHTO, and reduced the posterior slope increase and excessive varus deformity by 81.8% and 83.2%, respectively.

Conclusion

The current study revealed that supplemental screw insertion is a simple and effective technique to improve the structural stability and durability in medial owHTO.

Morphological changes affecting ipsilateral and contralateral leg alignment after total hip arthroplasty

Background

It is still unclear whether morphological changes in hip disorders is a pathogenic or independent factor for the variations in leg alignment. The purpose of this study was to elucidate the characteristics of the change in leg alignment after total hip arthroplasty (THA) and the morphological factors affecting the ipsilateral and contralateral leg alignment.

Methods

Both pre-operative and post-operative bilateral whole-leg radiographs in the standing position were taken in 100 patients who underwent THA. Hip-knee-ankle angle (HKAA), joint line convergence angle (JLCA), height of the hip center, lateral width to the hip center, femoral offset, and leg length discrepancy were measured. After the pre-operative legs were divided into the varus, neutral, or valgus groups, correlations between the change in HKAA and each hip morphological parameter were assessed.

Results

The mean change in HKAA on the THA side was 0.8° in the varus direction, which was significantly correlated with JLCA change. On the leg ipsilateral to THA, if the pre-operative alignment was valgus, the medial shift of the hip center was significantly correlated with the varus change in HKAA. On the side contralateral to THA, the change in leg length discrepancy was a significant correlative factor to the varus change in HKAA, if the pre-operative alignment was valgus or neutral.

Conclusion

The significant morphological parameters affecting the ipsilateral and contralateral leg alignment after THA were medial shifting of the hip center and the change in leg length discrepancy, respectively.

Level of evidence

Level Ⅳ, Retrospective cohort study.