In arthritis of the varus knee, a high tibial osteotomy (HTO) redistributes load from the diseased medial compartment to the unaffected lateral compartment. We report the outcome of 36 patients (33 men and three women) with 42 varus, arthritic knees who underwent HTO and dynamic correction using a Garches external fixator until they felt that normal alignment had been restored. The mean age of the patients was 54.11 years (34 to 68). Normal alignment was achieved at a mean 5.5 weeks (3 to 10) post-operatively. Radiographs, gait analysis and visual analogue scores for pain were measured pre- and post-operatively, at one year and at medium-term follow-up (mean six years; 2 to 10). Failure was defined as conversion to knee arthroplasty. . Pre-operative gait analysis divided the 42 knees into two equal groups with high (17 patients) or low (19 patients) adductor moments. After correction, a statistically significant (p < 0.001, t-test,) change in adductor moment was achieved and maintained in both groups, with a rate of failure of three knees (7.1%), and 89% (95% confidence interval (CI) 84.9 to 94.7) survivorship at medium-term follow-up. At final follow-up, after a mean of 15.9 years (12 to 20), there was a survivorship of 59% (95% CI 59.6 to 68.9) irrespective of adductor moment group, with a mean time to conversion to knee arthroplasty of 9.5 years (3 to 18; 95% confidence interval ± 2.5). . HTO remains a useful option in the medium-term for the treatment of medial compartment osteoarthritis of the knee but does not last in the long-term. . Cite this article: Bone Joint J 2016;98-B:601–7

Aims. The aim of this study was to compare any differences in the primary outcome (biphasic flexion knee moment during gait) of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) at one year post-surgery. Methods. A total of 76 patients (34 bi-UKA and 42 TKA patients) were analyzed in a prospective, single-centre, randomized controlled trial. Flat ground shod gait analysis was performed preoperatively and one year postoperatively. Knee flexion moment was calculated from motion capture markers and force plates. The same setup determined proprioception outcomes during a joint position sense test and one-leg standing. Surgery allocation, surgeon, and secondary outcomes were analyzed for prediction of the primary outcome from a binary regression model. Results. Both interventions were shown to be effective treatment options, with no significant differences shown between interventions for the primary outcome of this study (18/35 (51.4%) biphasic TKA patients vs 20/31 (64.5%) biphasic bi-UKA patients; p = 0.558). All outcomes were compared to an age-matched, healthy cohort that outperformed both groups, indicating residual deficits exists following surgery. Logistic regression analysis of primary outcome with secondary outcomes indicated that the most significant predictor of postoperative biphasic knee moments was preoperative knee moment profile and trochlear degradation (Outerbridge) (R. 2. = 0.381; p = 0.002, p = 0.046). A separate regression of alignment against primary outcome indicated significant bi-UKA femoral and tibial axial alignment (R. 2. = 0.352; p = 0.029), and TKA femoral sagittal alignment (R. 2. = 0.252; p = 0.016). The bi-UKA group showed a significant increased ability in the proprioceptive joint position test, but no difference was found in more dynamic testing of proprioception. Conclusion. Robotic arm-assisted bi-UKA demonstrated equivalence to TKA in achieving a biphasic gait pattern after surgery for osteoarthritis of the knee. Both treatments are successful at improving gait, but both leave the patients with a functional limitation that is not present in healthy age-matched controls. Cite this article: Bone Joint J 2022;103-B(4):433–443

This study compared the outcome of total knee replacement (TKR) in adult patients with fixed- and mobile-bearing prostheses during the first post-operative year and at five years’ follow-up, using gait parameters as a new objective measure. This double-blind randomised controlled clinical trial included 55 patients with mobile-bearing (n = 26) and fixed-bearing (n = 29) prostheses of the same design, evaluated pre-operatively and post-operatively at six weeks, three months, six months, one year and five years. Each participant undertook two walking trials of 30 m and completed the EuroQol questionnaire, Western Ontario and McMaster Universities osteoarthritis index, Knee Society score, and visual analogue scales for pain and stiffness. Gait analysis was performed using five miniature angular rate sensors mounted on the trunk (sacrum), each thigh and calf. The study population was divided into two groups according to age (≤ 70 years versus > 70 years).

Improvements in most gait parameters at five years’ follow-up were greater for fixed-bearing TKRs in older patients (> 70 years), and greater for mobile-bearing TKRs in younger patients (≤ 70 years). These findings should be confirmed by an extended age controlled study, as the ideal choice of prosthesis might depend on the age of the patient at the time of surgery.

Aims. Total knee arthroplasty (TKA) may provoke ankle symptoms. The aim of this study was to validate the impact of the preoperative mechanical tibiofemoral angle (mTFA), the talar tilt (TT) on ankle symptoms after TKA, and assess changes in the range of motion (ROM) of the subtalar joint, foot posture, and ankle laxity. Methods. Patients who underwent TKA from September 2020 to September 2021 were prospectively included. Inclusion criteria were primary end-stage osteoarthritis (Kellgren-Lawrence stage IV) of the knee. Exclusion criteria were missed follow-up visit, post-traumatic pathologies of the foot, and neurological disorders. Radiological angles measured included the mTFA, hindfoot alignment view angle, and TT. The Foot Function Index (FFI) score was assessed. Gait analyses were conducted to measure mediolateral changes of the gait line and ankle laxity was tested using an ankle arthrometer. All parameters were acquired one week pre- and three months postoperatively. Results. A total of 69 patients (varus n = 45; valgus n = 24) underwent TKA and completed the postoperative follow-up visit. Of these, 16 patients (23.2%) reported the onset or progression of ankle symptoms. Varus patients with increased ankle symptoms after TKA had a significantly higher pre- and postoperative TT. Valgus patients with ankle symptoms after TKA showed a pathologically lateralized gait line which could not be corrected through TKA. Patients who reported increased ankle pain neither had a decreased ROM of the subtalar joint nor increased ankle laxity following TKA. The preoperative mTFA did not correlate with the postoperative FFI (r = 0.037; p = 0.759). Conclusion. Approximately one-quarter of the patients developed ankle pain after TKA. If patients complain about ankle symptoms after TKA, standing radiographs of the ankle and a gait analysis could help in detecting a malaligned TT or a pathological gait. Cite this article: Bone Joint J 2023;105-B(11):1159–1167

Aims. A retrospective longitudinal study was conducted to compare directly volumetric wear of retrieved polyethylene inserts to predicted volumetric wear modelled from individual gait mechanics of total knee arthroplasty (TKA) patients. Methods. In total, 11 retrieved polyethylene tibial inserts were matched with gait analysis testing performed on those patients. Volumetric wear on the articular surfaces was measured using a laser coordinate measure machine and autonomous reconstruction. Knee kinematics and kinetics from individual gait trials drove computational models to calculate medial and lateral tibiofemoral contact paths and forces. Sliding distance along the contact path, normal forces and implantation time were used as inputs to Archard’s equation of wear to predict volumetric wear from gait mechanics. Measured and modelled wear were compared for each component. Results. Volumetric wear rates on eight non-delaminated components measured 15.9 mm. 3. /year (standard error (SE) ± 7.7) on the total part, 11.4 mm. 3. /year (SE ± 6.4) on the medial side and 4.4 (SE ± 2.6) mm. 3. /year on the lateral side. Volumetric wear rates modelled from patient gait mechanics predicted 16.4 mm. 3. /year (SE 2.4) on the total part, 11.7 mm. 3. /year (SE 2.1) on the medial side and 4.7 mm. 3. /year (SE 0.4) on the lateral side. Measured and modelled wear volumes correlated significantly on the total part (p = 0.017) and the medial side (p = 0.012) but not on the lateral side (p = 0.154). Conclusion. In the absence of delamination, patient-specific knee mechanics during gait directly affect wear of the tibial component in TKA. Cite this article: Bone Joint J 2020;102-B(6 Supple A):129–137

The purpose of this study was to investigate whether a gender-specific high-flexion posterior-stabilised (PS) total knee replacement (TKR) would offer advantages over a high-flex PS TKR regarding range of movement (ROM), ‘feel’ of the knee, pain and satisfaction, as well as during activity. A total of 24 female patients with bilateral osteoarthritis entered this prospective, blind randomised trial in which they received a high-flex PS TKR in one knee and a gender-specific high-flexion PS TKR in the other knee. At follow-up, patients were assessed clinically measuring ROM, and questioned about pain, satisfaction and daily ‘feel’ of each knee. Patients underwent gait analysis pre-operatively and at one year, which yielded kinematic, kinetic and temporospatial parameters indicative of knee function during gait. At final follow-up we found no statistically significant differences in ROM (p = 0.82). The median pain score was 0 (0 to 8) in both groups (p = 0.95). The median satisfaction score was 9 (4 to 10) in the high-flex group and 8 (0 to 10) in the gender-specific group (p = 0.98). The median ‘feel’ score was 9 (3 to 10) in the high-flex group and 8 (0 to 10) in the gender-specific group (p = 0.66). Gait analysis showed no statistically significant differences between the two prosthetic designs in any kinematic, kinetic or temporospatial parameters. Both designs produced good clinical results with significant improvements in several gait parameters without evidence of any advantage in the gender-specific design

Introduction. Identifying knee osteoarthritis patient phenotypes is relevant to assessing treatment efficacy. Biomechanical variability has not been applied to phenotyping, yet features may be related to outcomes of total knee arthroplasty (TKA), an inherently mechanical surgery. This study aimed to i) identify biomechanical phenotypes among TKA candidates based on demographic and gait mechanic similarities, and ii) compare objective gait improvements between phenotypes post-TKA. Methods. TKA patients underwent 3D gait analysis one-week pre (n=134) and one-year post-TKA (n=105). Principal component analysis was applied to frontal and sagittal knee angle and moment gait waveforms, extracting major patterns of variability. Demographics (age, sex, BMI), gait speed, and frontal and sagittal pre-TKA angle and moment principal component (PC) scores previously found to differentiate sex, osteoarthritis (OA) severity, and symptoms of TKA recipients were standardized (mean=0, SD=1, [134×15]) to perform multidimensional scaling and machine learning based hierarchical clustering. Final clusters were validated by examining inter-cluster differences at baseline and gait changes (Post. PCscore. –Pre. PCscore. ) by k-way Chi-Squared, and ANOVA tests. Results. Four (k=4) TKA candidate groups yielded optimum clustering metrics, interpreted as 1) high-functioning males, 2) older stiff-kneed males, 3) slower stiff-kneed females, and 4) high-functioning females. Pre-TKA, higher-functioning clusters (1 & 4) had more dynamic loading/un-loading kinetic patterns during stance (flexion moment PC2, 3<2<4<1, P<0.001; adduction moent PC2; 3,2<4<1; P<0.001). Post-TKA, higher-functioning clusters demonstrated less gait improvement (flexion angle ΔPC2, 1,2,4<3, P<0.001; flexion moment ΔPC2, 4<2,3, P<0.001; adduction moment ΔPC2, 1<3, P=0.01). Conclusions. TKA candidates can be characterized by four clusters, interpreted as 1) high-functioning males, 2) older stiff-kneed males, 3) slower stiff-kneed females, and 4) high-functioning females, differing by demographics and biomechanical severity features. Functional gains after TKA were cluster-specific; stiff-gait clusters experienced more improvement, while higher-functioning clusters demonstrated some functional decline. Results suggest the presence of cohorts who may not benefit functionally from TKA. Cluster profiling may aid in triaging and developing osteoarthritis management and surgical strategies that meet individual or group-level function needs. For figures, tables, or references, please contact authors directly

The aim of this study was to analyse the gait pattern, muscle force and functional outcome of patients who had undergone replacement of the proximal tibia for tumour and alloplastic reconstruction of the extensor mechanism using the patellar-loop technique. Between February 1998 and December 2009, we carried out wide local excision of a primary sarcoma of the proximal tibia, proximal tibial replacement and reconstruction of the extensor mechanism using the patellar-loop technique in 18 patients. Of these, nine were available for evaluation after a mean of 11.6 years (0.5 to 21.6). The strength of the knee extensors was measured using an Isobex machine and gait analysis was undertaken in our gait assessment laboratory. Functional outcome was assessed using the American Knee Society (AKS) and Musculoskeletal Tumor Society (MSTS) scores. The gait pattern of the patients differed in ground contact time, flexion heel strike, maximal flexion loading response and total sagittal plane excursion. The mean maximum active flexion was 91° (30° to 110°). The overall mean extensor lag was 1° (0° to 5°). The mean extensor muscle strength was 25.8% (8.3% to 90.3%) of that in the non-operated leg (p < 0.001). The mean functional scores were 68.7% (43.4% to 83.3%) (MSTS) and 71.1 (30 to 90) (AKS functional score). In summary, the results show that reconstruction of the extensor mechanism using this technique gives good biomechanical and functional results. The patients’ gait pattern is close to normal, except for a somewhat stiff knee gait pattern. The strength of the extensor mechanism is reduced, but sufficient for walking. . Cite this article: Bone Joint J 2015;97-B:1063–9

Introduction. Studies of retrieved total knee replacement (TKR) components demonstrate that in vivo wear on the articular surface of polyethylene liners exhibits a much higher variability than their in vitro counterparts tested on simulators. 1. Only one study has attempted to validate a patient-specific model of wear with a clinically retrieved component. 2. The purpose of this study is to investigate the relationship between observed TKR contact conditions during gait and measured volume loss on retrieved tibial components. Methods. Eleven retrieved ultra-high molecular weight polyethylene (UHMWPE) cruciate-retaining tibial liner components from ten separate patients (implantation time = 8.6±5.6 years) had matching gait trials of normal level walking for each knee. Volume loss on retrieved components was calculated using a coordinate measuring machine and autonomous reconstruction. 3. Motion analysis of normal level walking gait had been conducted between 1986 and 2005 for various previous studies and stored in a consented Human Mechanics Repository, ranging from pre-operative to long-term post-operative testing. Contact location between the femoral component and the tibial component on the medial and lateral plateaus were calculated throughout stance. 4. A previously validated and fine-tuned parametric numerical model was used to calculate TKR contact forces for each gait trial. 5. Vertical contact forces and contact paths on the medial and lateral plateaus were input as normal force and sliding distance to a simplified Archard equation for wear with material wear constant = 2.42 × 10. −7. mm. 3. /Nm. 2,6. to compute average wear per gait cycle. Wear rates were calculated using linear regression, and Pearson correlation examined correlations between modeled and measured wear. Results. Secondary motions at the knee from gait testing showed distinct grouping between trials of each patient (Fig. 1). Three components demonstrated severe polyethylene delamination and were excluded from wear rate analyses. All calculated wear rates for measured and modeled volume loss, shown in Fig. 2, showed excellent agreement and were not significantly different (Table 1). Measured wear rates were comparable to a previous study of a large population of retrieved Miller-Galante II components. 7. As seen in Fig 2b, medial wear volumes for six of eight mild wearing components were closely tracked by their modeled counterparts. Volumes were significantly correlated between measured and modeled wear for the total part and on the medial side, but not for the lateral side (Table 1). Conclusion. Because the Archard equation produces wear volumes that are linearly related to time in situ, deviations from linear predictions arise from patient-specific variations in contact forces and tibiofemoral pathways during normal walking gait. As suggested by the results of the current study, these variations in gait between patients result in meaningful differences to the wear of the UHMWPE component. Despite many assumptions, this study demonstrates the feasibility of a patient-specific model of wear using a rare population of gait-matched retrievals. This study suggests that gait analysis may play an important role in individualized medicine in orthopedics. For figures, tables, or references, please contact authors directly

The aim of this study was to examine the loading of the other joints of the lower limb in patients with unilateral osteoarthritis (OA) of the knee. We recruited 20 patients with no other symptoms or deformity in the lower limbs from a consecutive cohort of patients awaiting knee replacement. Gait analysis and electromyographic recordings were performed to determine moments at both knees and hips, and contraction patterns in the medial and lateral quadriceps and hamstrings bilaterally. The speed of gait was reduced in the group with OA compared with the controls, but there were only minor differences in stance times between the limbs. Patients with OA of the knee had significant increases in adduction moment impulse at both knees and the contralateral hip (adjusted p-values: affected knee: p < 0.01, unaffected knee p = 0.048, contralateral hip p = 0.03), and significantly increased muscular co-contraction bilaterally compared with controls (all comparisons for co-contraction, p < 0.01). The other major weight-bearing joints are at risk from abnormal biomechanics in patients with unilateral OA of the knee. Cite this article: Bone Joint J 2013;95-B:348–53

Aims

Adenosine, lidocaine, and Mg²⁺ (ALM) therapy exerts differential immuno-inflammatory responses in males and females early after anterior cruciate ligament (ACL) reconstruction (ACLR). Our aim was to investigate sex-specific effects of ALM therapy on joint tissue repair and recovery 28 days after surgery.

Aims

The metabolic equivalent of task (MET) score examines patient performance in relation to energy expenditure before and after knee arthroplasty. This study assesses its use in a knee arthroplasty population in comparison with the widely used Oxford Knee Score (OKS) and EuroQol five-dimension index (EQ-5D), which are reported to be limited by ceiling effects.

Aim. To determine the tensile forces across the knee extensor mechanism during walking, in simulated conditions of treatment. Methods. Gait analysis of six normal subjects was performed, with full weight bearing unilateral immobilisation of the knee during walking. Measurements were taken without then with a brace, unlocked then locked at 0°, 0-10°, 0-20° and 0-30° of flexion. Mean and maximum knee flexion angles were measured, followed by calculation of the mean and maximum forces across the extensor mechanism during loading, supporting and propulsion phases of gait. Results. The knee brace flexion angles set were consistently different to those measured kinematically, although the brace did act appropriately to restrict flexion. The highest flexion angles were found during the propulsion phase of gait. The calculated force through the extensor mechanism was greatest during the loading phase. The highest force recorded was with the brace locked between 0-10° of flexion, which in a 70kg person would be equivalent to a mean load of 343 N with a peak of 890 N. Discussion. The maximum forces for all conditions measured in our study exceed those published in the literature for failure strength of many common fixation devices. We recommend that full weight bearing during walking should be avoided in the injured limb, after the initial repair of the knee extensor mechanism

We describe the influence of the angle of immobilisation during partial weight-bearing on the forces across the extensor mechanism of the knee. Gait analysis was performed on eight healthy male subjects with the right knee in an orthotic brace locked at 0°, 10°, 20° and 30°, with the brace unlocked and also without a brace. The ground reaction force, the angle of the knee and the net external flexion movement about the knee were measured and the extensor mechanism force was calculated. The results showed a direct non-linear relationship between the angle of knee flexion and the extensor mechanism force. When a brace was applied, the lowest forces occurred when the brace was locked at 0°. At 30° the forces approached the failure strength of some fixation devices. We recommend that for potentially unstable injuries of the extensor mechanism, when mobilising with partial weight-bearing, the knee should be flexed at no more than 10°

Introduction. Patients with knee osteoarthritis frequently complain that they develop pain in other joints due to over-loading during gait. However, there have been no previous studies examining the effect of knee arthritis on the other weight bearing joints. The aim of this study was to examine the loading of the hips and contra-lateral knee during gait in a cohort of patients pre- and post knee replacement. Methods. Twenty patients with single joint osteoarthritis awaiting knee replacement and 20 healthy volunteers were recruited. Gait analysis during level gait and at self selected speed was performed using a 12 camera Vicon motion analysis system. The ground reaction force was collected using EMG electrodes attached to the medial and lateral hamstrings and quadriceps bilaterally. Patients were invited to return 12 months post-operatively. Data was analysed using the Vicon plug-in-gait model and statistical testing was performed with SPSS v16.0 using ANCOVA to account for gait speed. Results. The mean age of the patients was 69 (range 53-82) and the controls was 70 (range 60-83). Mid-stance moments and knee adduction impulses were elevated at both hips and both knees in patients compared to normal individuals (Impulses: OA Knee=1.87Nms; opposite knee=1.46Nms; controls=0.86Nms; p<0.01) whilst peak moments were not significantly different. Muscular co-contraction was elevated in both knees compared to normal (p<0.01). Ten patients returned for follow up. Correction of varus resulted in improvements in moments at the replaced knee however recovery of moments in the other joints was variable and dependant on alignment, gait speed and their ability to mobilise their centre of mass. Conclusion. Patients with single joint knee osteoarthritis have abnormal loading of both knees and both hips, potentially leading to further disease and disability. Recovery following knee replacement is variable and dependant on limb alignment and the patient's functional recovery

High flexion designs are intended to provide a greater range of knee flexion and possibly improve flexion in stiff knees. This study assessed the effects of two implant designs. A posterior stabilised high flexion mobile bearing (MB) design vs a cruciate retaining standard fixed bearing (FB) design. The aim of this study was to assess whether implant design has an effect on the functional outcome one year after total knee arthroplasty (TKA). Methods. Ninety patients with knee osteoarthritis on the waiting list for unilateral TKA were recruited and randomly allocated to either the MB or FB group. Patients were assessed between one and four weeks before, and one year after TKA. Primary outcome was knee flexion during high flexion activities of daily living such as stair ascending and descending and squatting as measured using gait analysis. Knee flexion in long sitting using a manual goniometer and the WOMAC were also recorded. Two sample t-tests were used to investigate statistical differences between the two groups pre- and postoperatively. Results. Average age was 69 years. Thirty-three received the MB design and 39 the FB design. Age, gender balance and pre-operative flexion (112 and 113 degrees in the FB and MB groups respectively) were the same in both groups. There were no statistically significant differences in post-operative knee flexion during functional activities. Knee flexion in sitting and the stiffness and function components of the WOMAC were also similar between the two groups (p>0.05). However, post-operatively the WOMAC pain component was slightly higher in the MB group (4.2 vs 2.4 points, p<0.05). Conclusion. In our patient group with a mean pre-operative flexion of 112.7 degrees, the high flexion mobile bearing design did not improve knee flexion during high flexion functional activities of daily living

Aims

In the last decade, interest in partial knee arthroplasties and bicruciate retaining total knee arthroplasties has increased. In addition, patient-related outcomes and functional results such as range of movement and ambulation may be more promising with less invasive procedures such as bicompartmental arthroplasty (BCA). The purpose of this study is to evaluate clinical and radiological outcomes after a third-generation patellofemoral arthroplasty (PFA) combined with a medial or lateral unicompartmental knee arthroplasty (UKA) at mid- to long-term follow-up.

Aims

This study aimed to identify the tibial component and femoral component coronal angles (TCCAs and FCCAs), which concomitantly are associated with the best outcomes and survivorship in a cohort of fixed-bearing, cemented, medial unicompartmental knee arthroplasties (UKAs). We also investigated the potential two-way interactions between the TCCA and FCCA.

Aims

This study aims to determine the proportion of patients with end-stage knee osteoarthritis (OA) possibly suitable for partial (PKA) or combined partial knee arthroplasty (CPKA) according to patterns of full-thickness cartilage loss and anterior cruciate ligament (ACL) status.

Aims

To compare the gait of unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) patients with healthy controls, using a machine-learning approach.