Abnormal ground reaction forces lead to a general decline in gait speed in knee osteoarthritis patients

AIM To analyse ground reaction forces at higher speeds using another method to be more sensitive in assessing significant gait abnormalities. METHODS A total of 44 subjects, consisting of 24 knee osteoarthritis(OA) patients and 20 healthy controls were analysed. The knee OA patients were recruited from an orthopaedic clinic that were awaiting knee replacement. All subjects had their gait patterns during stance phase at top walking speed assessed on a validated treadmill instrumented with tandem force plates. Temporal measurements and ground reaction forces(GRFs) along with a novel impulse technique were collected for both limbs and a symmetry ratio was applied to all variables to assess inter-limb asymmetry. All continuous variables for each group were compared using a student t-test and χ2 analysis for categorical variables with significance set at α = 0.05. Receiver operator characteristics curves were utilised to determine best discriminating ability.RESULTS The knee OA patients were older(66 ± 7 years vs 53 ± 9 years, P = 0.01) and heavier(body mass index: 31 ± 6 vs 23 ± 7, P < 0.001) but had a similar gender ratio when compared to the control group. Knee OA patients were predictably slower at top walking speed(1.37 ± 0.23 m/s vs 2.00 ± 0.20 m/s, P < 0.0001) with shorter mean step length(79 ± 12 cm vs 99 ± 8 cm, P < 0.0001) and broader gait width(14 ± 5 cm vs 11 ± 3 cm, P = 0.015) than controls without any known lower-limb joint disease. At a matched mean speed(1.37 ± 0.23 vs 1.34 ± 0.07), ground reaction results revealed that pushoff forces and impulse were significantly(P < 0.0001) worse(18% and 12% respectively) for the knee OA patients when compared to the controls. Receiver operating characteristic curves analysis demonstrated total impulse to be the best discriminator of asymmetry, with an area under the curve of 0.902, with a cut-off of-3% and a specificity of 95% and sensitivity of 88%.CONCLUSION Abnormal GRFs in knee osteoarthritis are clearly evident at higher speeds. Analysing GRFs with another method may explain the general decline in knee OA patient's gait.

Current concepts in the management of bisphosphonate associated atypical femoral fractures

Bisphosphonates are a class of drugs used as the mainstay of treatment for osteoporosis.Bisphosphonates function by binding to hydroxyapatite,and subsequently targeting osteoclasts by altering their ability to resorb and remodel bone.Whilst aiming to reduce the risk of fragility fractures,bisphosphonates have been associated with atypical insufficiency fractures,specifically in the femur.Atypical femoral fractures occur distal to the lesser trochanter,until the supracondylar flare.There are a number of the differing clinical and radiological features between atypical femoral fractures and osteoporotic femoral fractures,indicating that there is a distinct difference in the respective underlying pathophysiology.At the point of presentation of an atypical femoral fracture,bisphosphonate should be discontinued.This is due to the proposed inhibition of osteoclasts and apoptosis,resulting in impaired callus healing.Conservative management consists primarily of cessation of bisphosphonate therapy and partial weightbearing activity.Nutritional deficiencies should be investigated and appro-priately corrected,most notably dietary calcium and vitamin D.Currently there is no established treatment guidelines for either complete or incomplete fractures.There is agreement in the literature that nonoperative management of bisphosphonate-associated femoral fractures conveys poor outcomes.Currently,the favoured methods of surgical fixation are cephalomedullary nailing and plate fixation.Newer techniques advocate the use of both modalities as it gives the plate advantage of best reducing the fracture and compressing the lateral cortex,with the support of the intramedullary nail to stabilise an atypical fracture with increased ability to load-share,and a reduced bending moment across the fracture site.The evidence suggests that cephalomedullary nailing of the fracture has lower revision rates.However,it is important to appreciate that the anatomical location and patient factors may not always allow for this.Although causation between bisphosphonates and atypical fractures is yet to be demonstrated,there is a growing evidence base to suggest a higher incidence to atypical femoral fractures in patients who take bisphosphonates.As we encounter a growing comorbid elderly population,the prevalence of this fracture-type will likely increase.Therefore,it is imperative clinicians continue to be attentive of atypical femoral fractures and treat them effectively.

MRI Classification of Subtalar Joint Osteoarthritis Using a Novel Scoring System

Background: Plain radiography usual method to detect degeneration in the subtalar and talonavicluar joints. MRI is a better way to fully characterise non-ossified structures, such as articular cartilage, marrow tissue and synovial fluid and therefore detect changes of arthritis. The motivation behind this study was to develop a quantitative way to score arthritic changes to the subtalar and talonavicular joints using MRI. The developed system will then be used as a research tool and in the close assessment and monitoring of patients with hindfoot degenerative disease. Methods: The MRI scans of thirty consecutive subjects with foot and ankle pain were retrospectively evaluated. Images were interpreted independently by three musculoskeletal radiologists in order to determine intra-observer reliability as well as the inter-observer reliability of the score. Five features of osteoarthritis were scored in the Subtalar joint and the Talonavicular joint. These were cartilage morphology, subarticular marrow, subarticular cyst, marginal osteophytes and synovitis. Results: For the 30 MRI scans the mean score for the Subtalar joint ranged from 11.7 to 14.4 and for the Talonavicular joint ranged from 3.7 to 5.6. The inter-observer correlation for the Subtalar joint between the three readers ranged between 0.53 and 0.83 for the individual features but overall was excellent at 0.76. For the Talonavicular joint the total correlation was good at 0.67. The inter-observer ICC for the total score was 0.75 which showed excellent agreement between the three readers. The total intra-observer correlation was excellent. Conclusions: The current work has shown excellent reliability for the scoring system. It will be a useful tool to diagnose and monitor disease progression of the Subtalar and Talonavicluar joints.