Ceramic-on-Ceramic Total Hip Arthroplasty Using a Double Tapered, Proximally Coated Stem: 15 to 24-year Clinical and Radiologic Follow-Up.

BACKGROUND: Total hip arthroplasty implant choice profoundly affects survivorship, complications, and failure modes. This study evaluates the long-term (average 18 year) outcomes of ceramic-on-ceramic hip arthroplasty using uncemented shells and stems. Despite an impressive 20-year cumulative percent revision of 5.9%, the hydroxyapatite proximally coated femoral components evaluated in this study have seen declining use since 2003. METHODS: A review of 349 consecutive total hip arthroplasties from 1999 to 2007 was matched to 272 cases with registry data. A survivorship analysis included 274 hips (Group A) after excluding patients lost to follow-up and navigated cases. Group B comprised 135 patients who had complete datasets spanning a minimum of 15 years. RESULTS: Kaplan-Meier analysis identified a 95.6% survivorship plateau at 16 to 24 years, with no significant impact from age, sex, component size, or original pathology. In Group B, EuroQol-5 Dimensions-5 Levels (EQ5D5L) scores indicated favorable outcomes in mobility, self-care, activities, pain/discomfort, and anxiety/depression, with an EQ5D visual analog score mean of 79.24. Functional scores, including the Harris Hip Score, Oxford Hip Score, and Forgotten Joint Score, showed positive outcomes. Radiologic assessments revealed no osteolysis or loose components, with a mean Engh score of 21.69. Dorr classification identified bone quality variations. Better Engh scores corresponded to higher levels of patient satisfaction. Age at surgery was correlated with better functional scores, while sex influenced various outcomes. CONCLUSIONS: This comprehensive study, spanning an average of 18.23 years, combined multiple patient-reported outcome measures with extensive clinical and radiologic follow-up. It reported a notably high survivorship rate for this implant combination but highlighted the declining use of the hydroxyapatite proximally coated femoral stem used in this study, potentially facing withdrawal risks in Australia. LEVEL OF EVIDENCE: Therapeutic Level IV.

Tripolar Constrained and Dual Mobility Liners Are Both Successful When Cemented Into Tantalum Acetabular Revision Shells in Complex Revision Total Hip Arthroplasty.

BACKGROUND: Instability is a common complication after revision total hip arthroplasty. Tripolar constrained (TC) and dual mobility (DM) liners cemented into tantalum acetabular revision (TM) shells are established alternatives that reduce instability risk. This study compares outcomes of TC and DM liners cemented into TM shells in complex revision hip replacements. METHODS: Fifty cases using a TM shell and a TC or DM cemented liner with at least 12 months of follow-up were identified. There were 25 TC and 25 DM liners. Clinical, radiographic, and patient-reported outcomes were collected. Reasons for re-revision and failures were analyzed. RESULTS: The average age was 73 years in the TC group and 75 years in the DM group. The median follow-up duration was 50 months (23 - 96) and 13 months (12 - 21) for the TC and DM groups, respectively. The mean Harris Hip Score improved from 37 to 61 for the TC group and from 51 to 73 in the DM group at the last review. Two TC cases required revision for wear and liner failure. One DM insert was changed at reoperation for periprosthetic femur fracture. There were no failures of cement fixation in either group and no revisions for cup loosening. CONCLUSIONS: In complex revision hip replacement with a history of instability or judged to have a high risk of instability postoperatively, TC and DM liners cemented into tantalum revision shells are both successful, giving acceptable results. The improved arc of movement with DM liners, minimizing impingement, makes them preferable except when there is a global abductor deficiency or severe joint laxity.

The discrepancy between patient expectations and actual outcome reduces at the first 6 months following total knee replacement surgery.

PURPOSE: Patients undergoing total knee arthroplasty often have unfulfilled expectations from the surgery that can lead to dissatisfaction. This study aimed to examine the discrepancy between patients' expectations and actual functional abilities prior to undergoing knee replacement surgery, and at 6 and 12 months following the surgery. METHODS: A survey was undertaken of patients before, and 6 and 12 months post-surgery. The survey included the Knee Surgery Perception Questionnaire (KSPQ) to assess patients' current perception of their level of function and pain, their desired outcomes, and the discrepancy between the two. Pain, function and quality of life were also assessed. Repeated measure ANOVAs were used to assess differences between pre- and post-surgery. RESULTS: A total of 176 patients were surveyed. Significant differences in the KSPQ discrepancy scores (subscale and total scores) were demonstrated between the three assessment point times (p < 0.01). Paired t tests identified significant differences between the pre-surgery and 6-month KSPQ discrepancy scores, (p < 0.01) indicative of substantial improvement in physical function and slight reduction in expectations. Overall significant improvement (p < 0.01) was reported over time across all measures: physical function, pain and stiffness and quality of life. CONCLUSION: The discrepancy between patients' current abilities and their expectation changes following surgery, especially in the first 6 months post-surgery. Patients' goals might change as their function and pain improve post-surgery. Combining education programmes and discussion with the treating orthopaedic surgeons pre-operatively is important for the development of realistic, achievable expectations. LEVEL OF EVIDENCE: III.

Pre-operative predictors of post-operative falls in people undergoing total hip and knee replacement surgery: a prospective study.

INTRODUCTION: Pain and disability often persist following hip (THR) and knee replacement (TKR) surgery predisposing patients to increased risk of falling. This study identified pre-operative predictors for post-operative falls in TKR and THR patients, and the incidence and circumstances of falls in the 12 months post-surgery. MATERIALS AND METHODS: A survey was undertaken of patients before THR and TKR, and was repeated 12 months post-operation. The survey included (1) medical history and medications usage, (2) pain and function, (3) health-related and physical activity and (4) fear of falls and history of falls questionnaires. Patients were classified as 'fallers' (≥1 fall) or 'non-fallers' based on prospectively documented falls in the 12 months post-surgery. Binary logistic regression was conducted to identify independent pre-operative predictors of incident falls status. RESULTS: Eighty-two of the 243 participants (33.7%) reported ≥1 fall in the 12 months post-operatively [60 (34.1%) patients following TKR and 22 (32.8%) following THR]. The logistic regression model was statistically significant, χ 2 = 24.731, p < 0.001, the model explaining 22% of the variance in falls, and correctly classifying 73.7% of cases as fallers or non-fallers. Reduced SF-36v2 general health sub-scale, increased planned physical activity and previous falls in the preceding year were predictors of falls. Those reporting ≥1 fall pre-operatively were three times more likely to fall post-operatively. CONCLUSION: People awaiting hip or knee joint replacement surgery might present with complex conditions that predispose them to greater risk of falling post-operation. Review of general health and history of falling is recommended pre-operatively to identify patients at risk.

Development and validation of a questionnaire assessing discrepancy between patients' pre-surgery expectations and abilities and post-surgical outcomes following knee replacement surgery.

PURPOSE: The discrepancy between patient-desired outcomes and achievable functional outcomes is a source of patient dissatisfaction. This paper reports development and validation of a questionnaire to assess this discrepancy in patients undergoing knee replacement surgery. METHODS: The initial questionnaire (Knee Surgery Perception Questionnaire, KSPQ) comprised two parts. Part A, assessed patients' perception of their current level of function and pain, and Part B, assessed patients' desired outcomes of the surgery. Validation was carried out for Part A and then applied to Part B using a one-factor congeneric model and was tested in 185 patients preceding surgery. A discrepancy score between patients' expectations and desired outcome (Part B) and their perception of current function (Part A) was also calculated. Pearson correlations were used between the KSPQ total score and subscales and other knee-specific questionnaires to determine construct validity. RESULTS: The final best set of models included four items for each subscale with a Chi-square value of 7.3 (n.s). The subscales and the total KSPQ showed significant strong to moderate correlations with knee-specific questionnaires. The discrepancy score in each subscale and the overall score showed relatively large discrepancy between patients' expectations and their perception of current function; with higher discrepancy score reported for pain and walking. CONCLUSION: The KSPQ is a valid questionnaire to assess patients' expected and desired outcomes of knee replacement surgery and their perception of their current abilities and function, and discrepancy between these. The KSPQ now requires further investigation at different stages of recovery following surgery. LEVEL OF EVIDENCE: III.

The effects of osteoarthritis and age on skeletal muscle strength, Na+-K+-ATPase content, gene and isoform expression.

Knee osteoarthritis (OA) is a debilitating disorder prevalent in older populations that is accompanied by declines in muscle mass, strength, and physical activity. In skeletal muscle, the Na(+)-K(+) pump (NKA) is pivotal in ion homeostasis and excitability and is modulated by disuse and exercise training. This study examined the effects of OA and aging on muscle NKA in 36 older adults (range 55-81 yr), including 19 with OA (69.9 ± 6.5 yr, mean ± SD) and 17 asymptomatic controls (CON, 66.8 ± 6.4 yr). Participants completed knee extensor strength testing and a physical activity questionnaire. A vastus lateralis muscle biopsy was analyzed for NKA content ([(3)H]ouabain binding sites), α1-3- and ß1-3-isoform protein abundance (immunoblotting), and mRNA (real-time RT-PCR). The association between age and NKA content was investigated within the OA and CON groups and in pooled data. The NKA content was also contrasted between subgroups below and above the median age of 68.5 yr. OA had lower strength (-40.8%, P = 0.005), but higher NKA α2- (∼34%, P = 0.006) and α3-protein (100%, P = 0.016) abundance than CON and performed more incidental physical activity (P = 0.035). No differences were found between groups for NKA content, abundance of other NKA isoforms, or gene expression. There was a negative correlation between age and NKA content within OA (r = -0.63, P = 0.03) and with both groups combined (r = -0.47, P = 0.038). The NKA content was 25.5% lower in the older (69-81 yr) than in the younger (55-68 yr) subgroup. Hence older age, but not knee OA, was related to lowered muscle NKA content in older adults.

Relationship between foot function and medial knee joint loading in people with medial compartment knee osteoarthritis.

BACKGROUND: Dynamic joint loading, particularly the external knee adduction moment (KAM), is an important surrogate measure for the medio-lateral distribution of force across the knee joint in people with knee osteoarthritis (OA). Foot motion may alter the load on the medial tibiofemoral joint and hence affect the KAM. Therefore, this study aimed to investigate the relationship between tibia, rearfoot and forefoot motion in the frontal and transverse planes and the KAM in people with medial compartment knee OA. METHOD: Motion of the knee, tibia, rearfoot and forefoot and knee moments were evaluated in 32 patients with clinically and radiographically-confirmed OA, predominantly in the medial compartment. Pearson's correlation coefficient was used to investigate the association between peak values of tibia, rearfoot and forefoot motion in the frontal and transverse planes and 1st peak KAM, 2nd peak KAM, and the knee adduction angular impulse (KAAI). RESULTS: Lateral tilt of the tibia was significantly associated with increased 1st peak KAM (r = 0.60, p < 0.001), 2nd peak KAM (r = 0.67, p = 0.001) and KAAI (r = 0.82, p = 0.001). Increased peak rearfoot eversion was significantly correlated with decreased 2nd peak KAM (r = 0.59, p < 0.001) and KAAI (r = 0.50, p = 0.004). Decreased rearfoot internal rotation was significantly associated with increased 2nd peak KAM (r = -0.44, p = 0.01) and KAAI (r = -0.38, p = 0.02), while decreased rearfoot internal rotation relative to the tibia was significantly associated with increased 2nd peak KAM (r = 0.43, p = 0.01). Significant negative correlations were found between peak forefoot eversion relative to the rearfoot and 2nd peak KAM (r = -0.53, p = 0.002) and KAAI (r = -0.51, p = 0.003) and between peak forefoot inversion and 2nd peak KAM (r = -0.54, p = 0.001) and KAAI (r = -0.48, p = 0.005). CONCLUSION: Increased rearfoot eversion, rearfoot internal rotation and forefoot inversion are associated with reduced knee adduction moments during the stance phase of gait, suggesting that medial knee joint loading is reduced in people with OA who walk with greater foot pronation. These findings have implications for the design of load-modifying interventions in people with knee OA.

Trochanteric non-union following revision hip replacement is associated with a poor functional outcome: a matched, case-control study.

The aim of this study was to determine the functional outcome in patients with a trochanteric non-union following revision total hip replacement. Twenty-five consecutive patients with a unilateral, trochanteric non-union were individually matched for age, sex, body mass index and duration of follow-up to two control groups: 1) 25 patients who had a primary total hip replacement ('primary controls'); and 2) 25 patients who had a revision total hip replacement ('revision controls'). At a mean follow up of approximately four years, the Harris hip score (HHS) for the cases was significantly worse compared to the primary control group (p<0.0001) and the revision control group (p<0.0001), with an overall 'poor' outcome in over half of the patients. The physical component of the Short Form-12 (SF-12) score was also significantly worse for the cases compared to the primary control group (p = 0.001), while the difference in the mental component approached significance (p = 0.057). There was no difference in the SF-12 scores between the cases and the revision control group (p = 0.1 and p = 0.4, respectively). A non-union of the greater trochanter is associated with a poor functional outcome following revision total hip replacement.

Lower limb biomechanics in individuals with knee osteoarthritis before and after total knee arthroplasty surgery.

We investigated the biomechanical changes that occur in the lower limb following total knee arthroplasty (TKA). Lower limb joint kinematics and kinetics were evaluated in 32 patients before and 12 months following TKA and 28 age-matched controls. Analysis of variance with Bonferroni-adjusted post-hoc tests showed no significant changes in knee joint kinematics and kinetics following TKA despite significant improvements in pain and function. Significant increases in peak ankle plantarflexion and dorsiflexion moments and ankle power generation were observed which may be a compensatory response to impaired knee function to allow sufficient power generation for propulsion. Differences in knee gait parameters may arise as a result of the presence of osteoarthritis and mechanical changes associated with TKA as well as retention of the pre-surgery gait pattern.

Foot kinematics in people with medial compartment knee osteoarthritis.

OBJECTIVES: Foot orthoses are commonly used in the management of knee OA, although the relationship between foot function and knee OA is still unclear. The purpose of the study was to examine foot function during walking in people with and without medial compartment knee OA. METHODS: Motion of the tibia, rearfoot and forefoot in 32 patients with medial compartment knee OA and 28 age-matched control subjects was investigated. Multivariate analysis was used to compare the groups. RESULTS: The knee OA group contacted the ground with a more everted rearfoot, demonstrated greater peak rearfoot eversion and exhibited reduced rearfoot frontal plane range of motion and reduced rearfoot peak inversion. The tibia was more internally rotated and laterally tilted throughout the gait cycle, with reduced peak external rotation. CONCLUSION: People with medial compartment knee OA exhibit altered foot kinematics during gait that are indicative of a less mobile, more everted foot type. The presence and degree of tibial malalignment and the available rearfoot range of motion during walking may affect individual responses to load-altering interventions, such as foot orthoses and footwear modifications. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry, www.anzctr.org.au/, ACTRN12608000116325.

Dynamic foot function changes following total knee replacement surgery.

BACKGROUND: Individuals with knee osteoarthritis (OA) have flatter/more pronated feet than those without OA, but it is unclear whether altered foot posture and function are a cause or consequence of knee OA. The purpose of this study was to examine whether changes in foot posture and function occur after realignment of the knee following total knee replacement (TKR). MATERIALS AND METHODS: Nineteen patients with predominantly medial compartment knee OA were tested prior to and 12 months after TKR. The Foot Posture Index (FPI) and Arch Index (AI) were measured as well as motion of the tibia, rearfoot and forefoot using a 3D motion analysis system incorporating a multisegment foot model. RESULTS: There were no significant changes in FPI or AI following TKR, however gait analysis revealed significant increases in tibial external rotation (-18.7 ± 7.0° vs -22.5 ± 8.7°, p=0.002), tibial transverse plane range of motion (-9.1 ± 4.6° vs -11.4 ± 6.1°, p=0.0028) and rearfoot range of motion in the frontal plane (8.6 ± 2.6° vs 10.4 ± 2.7°, p=0.002), and a decrease in rearfoot transverse plane range of motion (8.7 ± 5.3° vs 5.9 ± 4.1°, p=0.038) following the procedure. CONCLUSIONS: TKR produces no change in static foot posture, but results in significant changes in rearfoot kinematics during gait. These findings suggest that rearfoot motion compensates for changes in the alignment of the knee, highlighting the ability of the foot to accommodate for proximal skeletal malalignment.

Swing limb mechanics and minimum toe clearance in people with knee osteoarthritis.

OBJECTIVE: Knee osteoarthritis (OA) has been shown to be a risk factor for falls. Reductions in foot clearance during the swing phase of walking can cause a trip and potentially lead to a fall. This study examined the swing phase mechanics of people with and without knee OA during walking. DESIGN: Minimum toe clearance (MTC) height, joint angles at the time of MTC and the influence of the angular changes of the hip, knee and ankle of the swing leg on foot clearance using sensitivity analysis were investigated in 50 knee OA participants and 28 age-matched asymptomatic controls. RESULTS: Although both groups had a similar MTC height (controls: 12.8±6.7 mm, knee OA: 13.4±7.0 mm), the knee OA group used a different strategy to achieve the same foot clearance, as evidenced by greater knee flexion (52.5±5.3° vs 49.4±4.8°, p=0.007), greater hip abduction (-3.6±3.3° vs -1.8±3.3°, p=0.03) and less ankle adduction (2.8±1.9° vs 4.2±2.1°, p=0.01). CONCLUSION: MTC height was comparable between the groups, however a different swing phase mechanism was used by the knee OA. Although adequate MTC is an important component of safe locomotion, it does not appear to be impaired in people with knee OA. Other factors, such as inadequate responses to postural perturbation, may be responsible for falls in this group.

Lower limb proprioception deficits persist following knee replacement surgery despite improvements in knee extension strength.

PURPOSE: Knee pain and disability can persist following knee replacement surgery which may place patients at increased risk of falls. This study investigated the falls risk and the occurrence of falls of people with knee osteoarthritis (OA) before and at 12 months following knee replacement surgery. METHOD: Thirty-five patients with knee OA were tested prior to undergoing knee replacement surgery and at 12 months following surgery using the short form Physiological Profile Assessment, which incorporates tests of vision, lower limb proprioception, knee extension strength, reaction time and postural sway. Physical activity, number of falls, fear of falling, pain, disability and health-related quality of life were also assessed. RESULTS: No significant differences were found between the number of falls pre- and post-surgery (n.s.), with 48.5 and 40% reporting at least one fall in the 12 months before and following the surgery, respectively. Improvements in knee strength, reaction time and fear of falling were evident following surgery, with no improvement in lower limb proprioception. Self-reported pain, function and stiffness were significantly improved, but health-related quality of life deteriorated following the surgery. CONCLUSION: The number of falls experienced following knee replacement surgery remained relatively high, which may be attributed to the persistence of impaired lower limb proprioception. Although knee replacement surgery improves function and alleviates pain, people who undergo this procedure may need to engage in rehabilitation following the surgery to reduce the risk of falling. LEVEL OF EVIDENCE: Therapeutic study investigating the result of treatment on patient outcomes, Level IV.

Knee biomechanics early after knee replacement surgery predict abnormal gait patterns 12 months postoperatively.

An abnormal flexor moment pattern is often evident following total knee replacement (TKR) surgery. We investigated whether such a pattern at 12 months post-surgery could be predicted using biomechanical gait measures assessed before surgery and at 4 months post-surgery. Thirty two TKR patients were evaluated and classified as normal (biphasic pattern) or abnormal (flexor moment pattern) at each time point. Biomechanical parameters collected before surgery and at 4 months post-surgery were then explored for their ability to predict gait patterns at 12 months post-surgery. The gait pattern at 4 months was significantly associated with the 12 month post-surgery gait pattern, with over half of those with a flexor moment pattern at 4 months retaining this pattern at 12 months. Discriminant function analysis indicated that peak knee flexion during early stance, peak knee extension, and peak knee extension moment at 4 months post-surgery were independent predictors of the gait pattern at 12 months. Thus, an abnormal knee flexor moment pattern at 12 months post-surgery can be predicted by biomechanical analysis 4 months after surgery. Therefore, interventions aimed at improving active extension may need to be implemented early after surgery to restore a normal gait pattern.

Association between skeletal muscle inflammatory markers and walking pattern in people with knee osteoarthritis.

OBJECTIVE: Patients with knee osteoarthritis (OA) are characterized by increased muscle inflammation and altered gait. We investigated the association between proinflammatory mediators in the vastus lateralis and physical function and gait in patients with knee OA. METHODS: Nineteen patients with knee OA underwent gait analysis, assessment of self-reported pain and physical function (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]), and a muscle biopsy that was taken during their knee replacement surgery. Muscle was analyzed for cellular protein inflammatory mediators, interleukin-6, monocyte chemotactic protein 1 (MCP-1), p65 NF-κB, signal transducer and activator of transcription 3 (STAT-3), and JNK-1. Sagittal plane knee function, including early stance knee range of motion (ROM) and knee sagittal plane impulse, was measured using a motion analysis system. Pearson's correlation was used to assess relationships between selected variables. RESULTS: Significant positive correlations were found between MCP-1 and self-perceived stiffness, physical function, and the total WOMAC score (P < 0.05). MCP-1 was also negatively correlated with early stance knee ROM (r = -0.52, P = 0.023). Reduced velocity was associated with elevated levels of p65 NF-κB and STAT-3 (P < 0.05). Knee sagittal plane impulse was negatively correlated with JNK-1 (P = 0.02), indicating reduction in knee impulse with an increased level of JNK-1. CONCLUSION: Increased levels of several proinflammatory mediators were correlated with altered knee function during walking as well as greater physical disability and slower gait velocity. Identification of the cellular and molecular mechanisms associated with muscle inflammation is important to better understand the underlying mechanism responsible for altered gait and function in patients with knee OA.

Increased inflammatory cytokine expression in the vastus lateralis of patients with knee osteoarthritis.

OBJECTIVE: Increased inflammation and pain are inseparable parts of knee osteoarthritis (OA) that may lead to disuse of the affected limb. The aim of this study was to examine the effects of knee OA on inflammation- and atrophy-related genes and proteins in the vastus lateralis muscle of patients with knee OA. METHODS: Nineteen patients with knee OA and 14 asymptomatic control subjects matched for age and body mass index underwent strength measurements and a muscle biopsy. Muscle was analyzed for the total cellular protein of inflammatory kinases (p65 NF-κB, JNK1/2, STAT-3, and suppressor of cytokine signaling 3 [SOCS-3]) and inflammatory intracellular molecules (interleukin-6 [IL-6], IL-8, monocyte chemoattractant protein 1 [MCP-1], tumor necrosis factor α [TNFα], IL-1ß, and atrogin-1). RESULTS: Knee OA resulted in greater levels of IL-6 protein (34%; P = 0.002). The levels of inflammatory kinases, including STAT-3 (187%; P = 0.002), p65 NF-κB (156%; P = 0.002), and JNK1 (179%; P = 0.027), were also elevated. Furthermore, elevated expression of gene transcripts encoding MCP-1 (28%; P = 0.023), TNFα (85%; P < 0.001), and SOCS-3 (38%; P = 0.055) was observed in patients with knee OA compared with control subjects. Patients with knee OA had reduced muscle strength compared with control subjects (mean ± SEM 84.7 ± 8.7 versus 143.1 ± 20.8 Nm; P = 0.005). Negative correlations were observed between muscle strength and MCP-1 protein abundance (r = -0.37 [P = 0.042]) and the gene expression of TNFα and atrogin-1 messenger RNA (r = -0.46 [P = 0.012] and r = -0.36 [P = 0.040], respectively). CONCLUSION: Gene expression and the protein abundance of numerous muscle markers of inflammation and atrophy were elevated in patients with knee OA, and the increase in muscle inflammation was associated with a reduction in muscle strength. Given the role inflammation markers may play in muscle strength and atrophy, further studies are needed to investigate the effect of exercise intervention on skeletal muscle inflammation.

Physiological risk factors for falls in people with knee osteoarthritis before and early after knee replacement surgery.

PURPOSE: Knee osteoarthritis (OA) is a major cause of disability and a risk factor for falls in older people. The purpose of this study was to assess the falls risk of people with knee OA before surgery and at 4 months following surgery and to compare this to a control group. METHODS: Thirty-five patients with knee OA prior to undergoing knee replacement surgery and 27 asymptomatic age-matched controls participated in the study. The surgical group were tested prior to their surgery and at 4 months post-surgery. The short form of the Physiological Profile Assessment was used to assess falls risk and included tests of vision, lower limb proprioception, knee extension strength, reaction time and postural sway. Physical activity, quality of life, fear of falls and disability before and after surgery were also documented. RESULTS: At least one fall in the previous 12 months was reported for 48% of the surgical group compared with 30% of the control group. Following the surgery, there was a reduction in fear of falling and pain, and improvements in function for the surgical group. However, compared to the control group, the surgical group exhibited a greater fear of falling and reduced lower limb proprioception and knee extension strength both pre- and post-surgery. CONCLUSION: People who undergo knee replacement surgery may be at increased risk of falls both prior to and 4 months following their surgery, primarily due to deficits in knee extension strength and lower limb proprioception. Therefore, interventions to reduce the risk of falls should be implemented early after the surgery.

Foot posture in people with medial compartment knee osteoarthritis.

BACKGROUND: Foot posture has long been considered to contribute to the development of lower limb musculoskeletal conditions as it may alter the mechanical alignment and dynamic function of the lower limb. This study compared foot posture in people with and without medial compartment knee osteoarthritis (OA) using a range of clinical foot measures. The reliability of the foot measures was also assessed. METHODS: The foot posture of 32 patients with clinically and radiographically-confirmed OA predominantly in the medial compartment of the knee and 28 asymptomatic age-matched healthy controls was investigated using the foot posture index (FPI), vertical navicular height and drop, and the arch index. Independent t tests and effect size (Cohen's d) were used to investigate the differences between the groups in the foot posture measurements. RESULTS: Significant differences were found between the control and the knee OA groups in relation to the FPI (1.35 ± 1.43 vs. 2.46 ± 2.18, p = 0.02; d = 0.61, medium effect size), navicular drop (0.02 ± 0.01 vs. 0.03 ± 0.01, p = 0.01; d = 1.02, large effect size) and the arch index (0.22 ± 0.04 vs. 0.26 ± 0.04, p = 0.04; d = 1.02, large effect size). No significant difference was found for vertical navicular height (0.24 ± 0.03 vs. 0.23 ± 0.03, p = 0.54; d = 0.04, negligible effect size). CONCLUSION: People with medial compartment knee OA exhibit a more pronated foot type compared to controls. It is therefore recommended that the assessment of patients with knee OA in clinical practice should include simple foot measures, and that the potential influence of foot structure and function on the efficacy of foot orthoses in the management of medial compartment knee OA be further investigated.