True Mechanical Alignment is Found Only on Full-Limb and not on Standard Anteroposterior Radiographs

Knee osteotomies are becoming widely accepted and increasingly used, but rehabilitation techniques still vary widely between surgeons: A survey on current trends

Purpose

The purpose of this research survey was to report the current trends regarding the frequency, indications and techniques of knee osteotomies used in sports medicine practices over the past 5 years and during fellowship training.

Methods

Two Institutional Review Board-exempt anonymous surveys were electronically distributed between May 2023 and August 2023. A 19-question survey was sent to active members of the American Orthopaedic Society for Sports Medicine and European Society of Sports Traumatology, Knee Surgery and Arthroscopy societies and another 36-question survey was sent to orthopaedic sports medicine fellows near the end of their training. The surveys included questions regarding type and frequency of osteotomies performed, surgical indications, surgical techniques, preoperative planning and post-operative weight-bearing restrictions. Inclusion criteria were those who currently perform knee osteotomy surgery. Descriptive statistics were used for all comparisons.

Results

A total of 100 sports medicine surgeons and 26 sports medicine fellows participated in the survey. The most common type of osteotomy performed was a medial opening-wedge proximal tibial osteotomy for both surgeons (96%) and fellows (92%). The most used methods to assess coronal and sagittal alignment were long-leg radiographs (98% for surgeons) and lateral radiographs (66% for surgeons), respectively. Rehabilitation techniques varied between surgeons and fellows and depended on the technique, size of correction and hardware.

Conclusion

Osteotomies are becoming widely accepted as useful techniques to correct bony malalignment. Surgeons are increasing their use of osteotomies, and fellows in training are optimistic about the use of new technologies for osteotomy planning and execution. Trends suggest that osteotomies to correct varus and valgus malalignment for osteoarthritis are the most common, and rehabilitation techniques vary widely between surgeons.

Level of Evidence

Level V.

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.

Reliability and validity of OpenPose for measuring hip-knee-ankle angle in patients with knee osteoarthritis

We aimed to assess the reliability and validity of OpenPose, a posture estimation algorithm, for measuring hip-knee-ankle (HKA) angle in patients with knee osteoarthritis, by comparing it with radiography. In this prospective study, we analysed 60 knees (30 patients) with knee osteoarthritis. We measured HKA angle using OpenPose and radiography before or after total knee arthroplasty and assessed the test-retest reliability of each method with intraclass correlation coefficient (1, 1). We evaluated the ability to estimate the radiographic measurement values from the OpenPose values using linear regression analysis and used intraclass correlation coefficients (2, 1) and Bland-Altman analyses to evaluate the agreement and error between OpenPose and radiographic measurements. OpenPose had excellent test-retest reliability (intraclass correlation coefficient (1, 1) = 1.000) and excellent agreement with radiography (intraclass correlation coefficient (2, 1) = 0.915), with regression analysis indicating a large correlation (R² = 0.865). OpenPose also had a 1.1° fixed error and no systematic error when compared with radiography. This is the first study to validate the use of OpenPose for the estimation of HKA angle in patients with knee osteoarthritis. OpenPose is a reliable and valid tool for measuring HKA angle in patients with knee osteoarthritis. OpenPose, which enables non-invasive and simple measurements, may be a useful tool to assess changes in HKA angle and monitor the progression and post-operative course of knee osteoarthritis. Furthermore, this validated tool can be used not only in clinics and hospitals, but also at home and in training gyms; thus, its use could potentially be expanded to include self-assessment/monitoring.

Significant changes in lower limb alignment due to flexion and rotation-a systematic 3D simulation of radiographic measurements

BACKGROUND

Many radiographic lower limb alignment  measurements are dependent on patients' position, which makes a standardised image acquisition of long-leg radiographs (LLRs) essential for valid measurements. The purpose of this study was to investigate the influence of rotation and flexion of the lower limb on common radiological alignment parameters using three-dimensional (3D) simulation.

METHODS

Joint angles and alignment parameters of 3D lower limb bone models (n = 60), generated from computed tomography (CT) scans, were assessed and projected into the coronal plane to mimic radiographic imaging. Bone models were subsequently rotated around the longitudinal mechanical axis up to 15° inward/outward and additionally flexed along the femoral intercondylar axis up to 30°. This resulted in 28 combinations of rotation and flexion for each leg. The results were statistically analysed on a descriptive level and using a linear mixed effects model.

RESULTS

A total of 1680 simulations were performed. Mechanical axis deviation (MAD) revealed a medial deviation with increasing internal rotation and a lateral deviation with increasing external rotation. This effect increased significantly (p < 0.05) with combined flexion up to 30° flexion (- 25.4 mm to 25.2 mm). With the knee extended, the mean deviation of hip-knee-ankle angle (HKA) was small over all rotational steps but increased toward more varus/valgus when combined with flexion (8.4° to - 8.5°). Rotation alone changed the medial proximal tibial angle (MPTA) and the mechanical lateral distal femoral angle (mLDFA) in opposite directions, and the effects increased significantly (p < 0.05) when flexion was present.

CONCLUSIONS

Axial rotation and flexion of the 3D lower limb has a huge impact on the projected two-dimensional alignment measurements in the coronal plane. The observed effects were small for isolated rotation or flexion, but became pronounced and clinically relevant when there was a combination of both. This must be considered when evaluating X-ray images. Extension deficits of the knee make LLR prone to error and this calls into question direct postoperative alignment controls.

LEVEL OF EVIDENCE

III (retrospective cohort study).

The Lawrence D. Dorr Surgical Techniques & Technologies Award: Patient Acceptable Symptom State (PASS) in Medial and Lateral Unicompartmental Knee Arthroplasty: Does the Status of the ACL Impact Outcomes?

BACKGROUND

The aim of this study is to determine if there is a difference in the percentage of patients who reach Patient Acceptable Symptom State (PASS) when comparing anterior cruciate ligament (ACL)-deficient and ACL-intact knees following fixed-bearing medial and lateral unicompartmental knee arthroplasty (UKA).

METHODS

A consecutive series of 215 knees that underwent UKA (medial = 158, lateral = 57) were included in the study. The Knee Osteoarthritis Outcome Score functional score [KOOS activities of daily living (ADL)] and KOOS Sport were used as the primary outcome variables. A KOOS ADL PASS of 87.5 and KOOS Sport PASS of 43.8 were previously described for total knee arthroplasty (TKA). Failure was defined as conversion to TKA.

RESULTS

There were 157 in the ACL-intact group and 58 in the ACL-deficient group. Conversion to TKA was 3.7%. The failure rate in the ACL-deficient group was 5% (3/58) and 3% (5/157) in the ACL-intact group (P = .447). The mean survival for the entire group was 18.1 years (95% confidence interval 17.6-18.6). At 10 years, the survival was 94.3% (standard error = 0.028) in the ACL-deficient group and 97.6% (standard error = 0.014) in the ACL-intact group. At a mean 10 ± 3.5 years, with 93% follow-up, 83% in the ACL-deficient group and 80% in the ACL-intact group reached PASS for KOOS ADL (P = .218). For KOOS Sport, 85% of the ACL-deficient group compared to 81% in the ACL-intact group (P = .374) reached PASS.

CONCLUSION

The ACL-deficient cohort results were not significantly different compared to ACL-intact knees in both medial and lateral compartment UKA. Fixed-bearing medial and lateral UKA resulted in low failure rate and excellent long-term outcomes.

What is the "safe zone" for transition of coronal alignment from systematic to a more personalised one in total knee arthroplasty? A systematic review

PURPOSE

In total knee arthroplasty (TKA), implants are increasingly aligned based on emerging patient-specific alignment strategies, such as unrestricted kinematic alignment (KA), according to their constitutional limb alignment (phenotype alignment), which results in a large proportion of patients having a hip-knee angle (HKA) outside the safe range of ± 3° to 180° traditionally considered in the mechanical alignment strategy. The aim of this systematic review is to investigate whether alignment outside the safe zone of ± 3° is associated with a higher revision rate and worse clinical outcome than alignment within this range.

METHODS

A systematic literature search was conducted in PubMed, Embase, Cochrane and World of Science, with search terms including synonyms and plurals for "total knee arthroplasty", "alignment", "outlier", "malalignment", "implant survival" and "outcome". Five studies were identified with a total number of 927 patients and 952 implants. The Oxford Knee Score (OKS) and the WOMAC were used to evaluate the clinical outcome. The follow-up period was between 6 months and 10 years.

RESULTS

According to HKA 533 knees were aligned within ± 3°, 47 (8.8%) were varus outliers and 121 (22.7%) were valgus outliers. No significant differences in clinical outcomes were found between implants positioned within ± 3° and varus and valgus outliers. Likewise, no significant differences were found regarding revision rates and implant survival.

CONCLUSION

The universal use of the "safe zone" of ± 3° derived from the mechanical alignment strategy is hardly applicable to modern personalised alignment strategies in the light of current literature. However, given the conflicting evidence in the literature on the risks of higher revision rates and poorer clinical outcomes especially with greater tibial component deviation, the lack of data on the outcomes of more extreme alignments, and regarding the use of implants for KA TKA that are actually designed for mechanical alignment, there is an urgent need for research to define eventual evidence-based thresholds for new patient-specific alignment strategies, not only for HKA but also for FMA and TMA, also taking into account the preoperative phenotype and implant design. It is of utmost clinical relevance for the application of modern alignment strategies to know which native phenotypes may be reproduced with a TKA.

LEVEL OF EVIDENCE

IV.

A 2021 consensus statement on osteotomies around the knee by the UK Knee Osteotomy consensus Group (KOG)

BACKGROUND

There are significant deficiencies in the evidence base of modern-day osteotomy which result in significant variation in practice between surgeons. The purpose of this statement was to develop a consensus statement on the practice of osteotomy so that a more standardized approach to the indications, surgical technique, and postoperative care could be outlined. The article is also intended to educate and inform the practice of individuals who are early in their experience and/or clinical practice.

METHOD

A group of 29 specialist knee surgeons who regularly perform osteotomy was convened to form the Knee Osteotomy consensus Group (KOG). Consensus was determined utilizing the consensus group technique described by List. A total of 37 questions were asked covering all aspects of clinical practice.

RESULTS

20 statements were generated and debated until a criterion level of 70% was met.

CONCLUSIONS

Consensus was achieved regarding 20 statements concerning Indications for surgery, decision making, surgical planning, technique, post-operative assessment and recovery.

Reliability of Preoperative Planning Method That Considers Latent Medial Joint Laxity in Medial Open-Wedge Proximal Tibial Osteotomy

Background:

Soft tissue laxity around the knee joint has been recognized as a crucial factor affecting correction error during medial open-wedge proximal tibial osteotomy (MOWPTO). Medial laxity in particular, which represents the changes in joint-line convergence angle (JLCA), affects soft tissue correction.

Purpose:

The purpose of this study was to quantify medial laxity and develop a preoperative planning method that considers medial laxity.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

This study retrospectively reviewed 139 knees in 117 patients who underwent navigation-assisted MOWPTO from January 2014 to July 2019 for symptomatic medial compartment osteoarthritis with varus alignment >5°. We compared the results of 2 preoperative planning methods: conventional Miniaci (n = 47) and latent medial laxity reduction (LMLR) (n = 92). We evaluated the incidence of undercorrection, acceptable correction, and overcorrection. The radiologic parameters were analyzed using multiple linear regression with a stepwise selection model to establish an equation for the optimal preoperative planning method. The intraclass correlation coefficients (ICCs) of intraobserver, interobserver, and intermethod reliability were calculated.

Results:

The Miniaci method showed a higher incidence of overcorrection (55.3%) than the LMLR method (22.8%) at postoperative 6 months (P = .0006). Multiple linear regression with a stepwise selection model revealed a high correlation coefficient (R² = 0.888) for the following equation: Adjusted planned correction angle = 0.596 + 0.891 × Target correction angle – 0.255 × ΔJLCA_valgus. Upon simplification, the following equation showed the highest intermethod ICC value (0.991): Target correction angle – ⅓ΔJLCA_valgus, while the Miniaci method showed a relatively low ICC value of 0.875.

Conclusion:

There was a risk of overcorrection after MOWPTO using the conventional Miniaci method. An equation that considers medial laxity may help during preoperative planning for optimal correction during MOWPTO.

Staged Bilateral Total Knee Arthroplasty for Neglected Blount Disease Using a Gap Balancing Technique

Blount disease is an acquired, asymmetrical disorder of proximal tibial growth that results in a complex three-dimensional proximal tibial deformity, with tibial varus being the dominating feature. Although the exact pathophysiology is unknown, Blount disease is separated into 2 clinical variants, infantile and adolescent, based on the onset of symptoms occurring before or after the age of 10 years. If recognized and treated early, affected patients generally have a favorable prognosis; however, if neglected, it can lead to progressive malalignment and premature osteoarthritis. We present a patient with bilateral neglected Blount disease who underwent successful bilateral total knee arthroplasty performed in a staged fashion using a gap balancing technique with constrained condylar knee implants.

Patient-acceptable symptom state for reporting outcomes following unicompartmental knee arthroplasty : a matched pair analysis comparing UKA in ACL-deficient versus ACL-intact knees

AIMS

The patient-acceptable symptom state (PASS) is a level of wellbeing, which is measured by the patient. The aim of this study was to determine if the proportion of patients who achieved an acceptable level of function (PASS) after medial unicompartmental knee arthroplasty (UKA) was different based on the status of the anterior cruciate ligament (ACL) at the time of surgery.

METHODS

A total of 114 patients who underwent UKA for isolated medial osteoarthritis (OA) of the knee were included in the study. Their mean age was 65 years (SD 10). No patient underwent a bilateral procedure. Those who had undergone ACL reconstruction during the previous five years were excluded. The Knee injury Osteoarthritis Outcome Score Activities of Daily Living (KOOS ADL) function score was used as the primary outcome measure with a PASS of 87.5, as described for total knee arthroplasty (TKA). Patients completed all other KOOS subscales, Lysholm score, the Western Ontario and McMaster Universities Osteoarthritis Index, and the Veterans Rand 12-item health survey score. Failure was defined as conversion to TKA.

RESULTS

Survivorship at ten years was 97% in both the ACL-deficient and ACL-intact groups. The mean survival was 16.1 years (95% confidence interval (CI) 15.3 to 16.8) for the ACL-deficient group and 15.6 years (95% CI 14.8 to 16.361) for the ACL-intact group (p = 0.878). At a mean of nine years (SD 3.5) in the ACL-deficient group, 32 patients (87%) reached the PASS for the KOOS ADL. In the ACL-intact group, at a mean of 8.6 years (SD 3) follow-up, 63 patients (85%) reached PASS for the KOOS ADL. There was no significant difference in the percentage of patients who reached PASS for all KOOS subscales and Lysholm between the two groups.

CONCLUSION

PASS was achieved in 85% of all UKAs for KOOS ADL, similar to reports for TKA. Fixed-bearing, medial, non-robotically-assisted UKA resulted in 97% survival at ten years in both the ACL-deficient and ACL-intact groups. There was no significant difference in all outcomes between the two groups. Understanding PASS will allow better communication between surgeons and patients to improve the surgical management of patients with single compartment OA of the knee. This study provides mid- to long-term data supporting the use of PASS to document outcomes following UKA. PASS was met in more than 85% of patients with no differences between ACL-deficient and ACL-intact knees at a mean follow-up of nine years. Cite this article: Bone Joint J 2021;103-B(8):1367-1372.