The impact of reducing the femoral stem length in total hip arthroplasty during gait.

AIM: The length of the femoral stem in total hip arthroplasty (THA) is a practical consideration to prevent gait impairment. The aim of this study was to determine if reducing the femoral stem length in THA would lead to impaired gait biomechanics. METHODS: Patients uniformly with the same brand implant of differing lengths (100 mm vs 140-166 mm) were taken retrospectively from a prospective trial introducing a new short stem. Twelve patients without any other disorder to alter gait besides contralateral differing length stem THA were tested at differing gradients and speed on a validated instrumented treadmill measuring ground reaction forces. An anthropometrically similar group of healthy controls were analysed to compare. RESULTS: With the same posterior surgical approach, the offset and length of both hips were reconstructed within 5 mm of each other with an identical mean head size of 36 mm. The short stem was the last procedure for all the hips with gait analysis occurring at a mean of 31 and 79 months postoperatively for the short and long stem THA, respectively. Gait analysis between limbs of both stem lengths demonstrated no statistical difference during any walking condition. In the 90 gait assessments with three loading variables, the short stem was the favoured side 51% of the time compared 49% for the long stem. CONCLUSION: By testing a range of practical walking activities, no lower limb loading differences can be observed by reducing the femoral stem length. A shorter stem demonstrates equivalence in preference during gait when compared to a reputable conventional stem in total hip arthroplasty.

The unicompartmental knee is the preferred side in individuals with both a unicompartmental and total knee arthroplasty.

PURPOSE: To determine the preferred knee in patients with both one total and one unicompartmental knee arthroplasty. METHOD: Patients simply with a unicompartmental (UKA) and total knee arthroplasty (TKA) on contralateral sides were retrospectively screened from three senior knee surgeon's logs over a 15 year period. Patients safe and free from other diseases to affect gait were approached. A total of 16 patients (mean age 70 ± 8) agreed to ground reaction force testing on an instrumented treadmill at a fair pace and incline. A gender-ratio identical group of 16 healthy control subjects (mean age 67 ± 10) and 16 patients with ipsilateral medial knee OA (mean age 66 ± 7) were analysed to compare. RESULTS: Radiographically the mode preoperative Kellgren-Lawrence knee grade for each side was 3. Postoperatively, the TKA side had a mean coronal femoral component alignment of 7° and a mean tibial coronal alignment of 89° with a mean posterior slope of 5° in the sagittal plane. The UKA side had a mean coronal femoral component alignment of 7° and a mean tibial coronal alignment of 86° with a mean posterior slope of 4° in the sagittal plane. In 7 patients, the TKA was the first procedure, while 6 for the UKA and 3 done simultaneously. Gait analysis demonstrated in both walking conditions the UKA limb was the preferred side through all phases of loading (p < 0.05) and nearer to normal than the TKA limb when compared to healthy controls and patients with knee OA. The greatest difference was observed between the transition of weight acceptance and midstance (p = 0.008), when 22% more load was taken by the UKA side. CONCLUSION: By using a dynamic metric of an everyday activity, a distinct gait difference between differing arthroplasty types were established. A more natural loading pattern can be achieved with unicompartmentals as compared to total knees. LEVEL OF EVIDENCE: Retrospective comparative study, Level III.

The loading patterns of a short femoral stem in total hip arthroplasty: gait analysis at increasing walking speeds and inclines.

BACKGROUND: The purpose of this study was to examine the gait pattern of total hip arthroplasty (THA) patients with a new short femoral stem at different speeds and inclinations. MATERIALS AND METHODS: A total of 40 unilateral THA patients were tested on an instrumented treadmill. They comprised two groups (shorter stemmed THA n = 20, longer stemmed THA n = 20), both which had the same surgical posterior approach. The shorter femoral stemmed patients were taken from an ongoing hip trial with minimum 12 months postop. The comparative longer THR group with similar disease and severity were taken from a gait database along with a demographically similar group of healthy controls (n = 35). All subjects were tested through their entire range of gait speeds and inclines with ground reaction forces collected. Body weight scaling was applied and a symmetry index to compare the implanted hip to the contralateral normal hip. An analysis of variance with significance set at α = 0.05 was used. RESULTS: The experimental groups were matched demographically and implant groups for patient reported outcome measures and radiological disease. Both THA groups walked slower than controls, but symmetry at all intervals for all groups were not significantly different. Push-off loading was less favourable for both the shorter and longer stemmed THR groups (p < 0.05) depending on speed. CONCLUSIONS: Irrespective of femoral stem length, symmetry for ground reaction forces for both THA groups were returned to a normal range when compared to controls. However individual implant performance showed inferior (p < 0.05) push-off forces and normalised step length in both THR groups when compared to controls. LEVEL OF EVIDENCE: III.

The Effect of Hip Arthroplasty on Osteoarthritic Gait: A Blinded, Prospective and Controlled Gait Study at Fast Walking Speeds.

BACKGROUND: Painful unilateral cox arthrosis results in excessive forces passing through the "good leg." The impact of hip arthroplasty on contralateral leg gait has not been fully explored. We measured patients gait before and after arthroplasty, to answer 3 questions: (1) Are peak forces for the good legs outside the normal range? (2) Does arthroplasty protect contralateral limbs by reducing peak forces? and (3) Does arthroplasty result in a more symmetric and normal gait at fast walking speeds? METHODS: This prospective, controlled study, assessed ground reaction forces before and 13 months (range, 6-21 months) after hip arthroplasty. RESULTS: Peak ground reaction force in contralateral hips fell (1.45-1.38 times body weight, P = .04), whereas symmetry index maximum weight acceptance improved postoperatively (12.2 ± 11 vs 1.3 ± 6, P < .001). CONCLUSION: Although gait becomes more symmetrical, patients still experience higher peak loads than matched controls. These high forces may offer an explanation to the progression of arthrosis in lower limbs.

Downhill walking gait pattern discriminates between types of knee arthroplasty: improved physiological knee functionality in UKA versus TKA.

PURPOSE: To determine whether downhill walking gait pattern discriminates between different types of knee arthroplasty. METHODS: Nineteen unicompartmental knee arthroplasty (UKA) and fourteen total knee arthroplasty (TKA) patients who were well matched demographically and with high Oxford knee scores (OKS) for their operation type were evaluated at a minimum 1 year after their operation with downhill gait analysis. Nineteen healthy young subjects were used as controls. Downhill gait analysis was carried out on an instrumented treadmill that was ramped at the rear to produce a declination of 7°. All subjects after a period of habituation were tested for preferred and top downhill walking speed with associated ground reaction and temporospatial measurements. RESULTS: The UKA group had higher mean OKS (44.8 ± 2.9 vs 41.9 ± 4.7, p = 0.03) as predicted. The UKA group walked downhill 15% faster than the TKA group (1.75 ± 0.14 vs 1.52 ± 0.13 m/s, p < 0.0001) despite having the same cadence (134.9 ± 8.0 vs 133.9 ± 9.6 steps/min). This 15% difference in speed appeared largely due to a 15% increase in stride length (173 ± 14 vs 150 ± 17 cm, p = 0.0007) and normal weight acceptance, both of which were similar to the controls. CONCLUSION: Using an instrumented treadmill to test a commonly performed task, stride length when walking downhill highlights the functional differences between arthroplasty groups. Near normal restoration of physiological gait pattern was found in unicompartmentals as compared to total knee replacements. LEVEL OF EVIDENCE: Retrospective comparative study, Level III.

Resurfacing head size and femoral fracture: Are registry conclusions on head size justified?

BACKGROUND: Joint registries report that peri-prosthetic fractures are the most common reason for early revision of a hip resurfacing arthroplasty (HRA) and are twice as likely with small implant sizes. However, a national survey found peri-prosthetic fracture to be strongly associated with surgical accuracy. We therefore asked whether the force required to induce a peri-prosthetic fracture: (1) was significantly lower when using smaller implants and (2) correlated to the size of implant used, when surgery was performed accurately. METHODS: To ensure an adequate power, we calculated our sample size from pilot data. Forty-four femurs were tested in two experiments. The first experiment tested femurs with either a small (48 mm) or a large (54 mm) HRA implant. The second involved testing femurs with a range of implant sizes. A rapid prototyped femur-specific guide ensured accurate implantation. Specimens were then vertically loaded in a servo-hydraulic testing machine till fracture. Displacement (mm) and force (N) required for fracture were recorded. RESULTS: A median force of 1081 N was required to fracture specimens implanted with small 48-mm heads, while 1134 N was required when a 54-mm head was used (U = 77, z = -0.054, p = 0.957). Implant head size and force required to fracture were not related, r = 0.12, p = 0.63. CONCLUSIONS: The force required to induce a resurfacing peri-prosthetic fracture was not related to the size of the implant. The increased failure rate seen in all registries is unlikely to be directly the result of this single variable. Correctly performed resurfacing arthroplasty is highly resistant to fracture.

Health economics for intra-capsular hip fractures undertaking fixation.

BACKGROUND: Hip fracture is a common musculoskeletal injury in the elderly requiring surgery worldwide. The operative mainstay of intra-capsular hip fractures is arthroplasty with a smaller proportion for fixation. AIM: To determine the most beneficial method of fixation for patients with intra-capsular hip fractures. METHODS: A registered audit from 2012-2018 was conducted on all intra-capsular hip fractures treated with 2 commonly used fixation methods. Patient notes, electronic records and clinical codes for cost benefit were evaluated. A validated quality of life measure was collected at least 1 year after surgery. RESULTS: A total of 83 patients were identified with intra-capsular fractures undergoing fixation during the retrospective period. There were 47 cannulated cancellous screw and 36 sliding hip screw fixations with the case mix comparable for age, gender, co-morbidities and fracture configuration. There was no significant difference in blood loss, tip apex distance, radiation exposure, length of stay, radiological union time, collapse, avascular necrosis or re-operation between fixation methods. Logistic regression analysis demonstrated displaced intracapsular hip fractures correlated significantly with an undesirable outcome conferring a relative odds ratio of 7.25. There were 9 (19%) and 4 (11%) patients respectively, who required re-operation. There was no significant difference in health resource group tariff and implant cost with comparable EQ-5D and visual analogue scores. CONCLUSION: No significant advantage was identified with differing fixation type, but irrespective there were a high number of patients requiring re-operation. This was predicted by initial fracture displacement and patient age. Arthroplasty may need to be carefully considered for health economics and patient benefit.

Unicompartmental knee arthroplasty enables near normal gait at higher speeds, unlike total knee arthroplasty.

Top walking speed (TWS) was used to compare UKA with TKA. Two groups of 23 patients, well matched for age, gender, height and weight and radiological severity were recruited based on high functional scores, more than twelve months post UKA or TKA. These were compared with 14 preop patients and 14 normal controls. Their gait was measured at increasing speeds on a treadmill instrumented with force plates. Both arthroplasty groups were significantly faster than the preop OA group. TKA patients walked substantially faster than any previously reported series of knee arthroplasties. UKA patients walked 10% faster than TKA, although not as fast as the normal controls. Stride length was 5% greater and stance time 7% shorter following UKA - both much closer to normal than TKA. Unlike TKA, UKA enables a near normal gait one year after surgery.

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 appropriately 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 co-morbid 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.

Increased perioperative mortality for femoral neck fractures in patients with coronavirus disease 2019 (COVID-19): experience from the United Kingdom during the first wave of the pandemic.

BACKGROUND: The coronavirus disease 19 (COVID-19) pandemic has presented modern healthcare with an unprecedented challenge. At the peak of the pandemic, trauma and orthopaedic services at our institutions undertook internal restructuring, diverting resources to frontline medical care. Consequently, we sought to assess the impact on the elderly and comorbid patients presenting with femoral neck fractures, with a particular focus on 30-day mortality, length of stay, multidisciplinary team involvement and departmental structuring. METHOD: A retrospective analysis of patients presenting with femoral neck fractures at three separate West London NHS Trusts was undertaken between March 11, 2020, to April 30, 2020. Length of stay, 30-day mortality and adherence to parameters constituting the best care evidence-based practice tariffs were compared between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive and negative patients. A similar comparison was also conducted between our cohort and the equivalent period in 2018 using data from the National Hip Fracture Database. RESULTS: A total of 68 patients presenting with femoral neck fractures were identified, mean age 81 (range 38-98), 73% female. There were 10 confirmed/suspected cases of COVID-19 on admission and a further seven confirmed as inpatients. The 30-day mortality within our cohort was 11.76% compared to 6% nationally in 2018 (p = 0.045). Orthogeriatric reviews occurred within 72 h in 71% of cases compared to 88% in the equivalent 2018 period. Within the cohort, mean length of stay was 17.13 days (SD 5.6, range 8-27 days) for SARS-CoV-2 positive patients compared to 10 days (SD 8.7, range 1-53 days) for negative patients (p < 0.05). Thirty-two patients (47%) required increased packages of care on discharge or rehabilitation. CONCLUSIONS: The increase in 30-day mortality for SARS-CoV-2 positive patients presenting with femoral neck fractures is multifactorial, resulting from a combination of the direct effects of COVID-19 pneumonia as well as changes to the delivery of orthopaedic services. The provision of multidisciplinary care was directly affected by staff redeployment, particularly reorganisation of orthogeriatric services and lack of continuity of ward based clinical care. Our experiences have re-directed efforts towards the management of theatre teams, patient services and staffing, should we be faced with either a resurgence of COVID-19 or a future pandemic.

Tibial Plateau Fracture: Anatomy, Diagnosis and Management.

Tibial plateau fractures are peri-articular knee fractures of the proximal tibia. The presentation is dependent on the mechanism of injury. The tibial plateau is the bony platform of the distal half of the knee joint, and is made up of a medial and lateral condyle separated by the intercondylar eminence. The presentation of tibial plateau fractures can vary greatly as a result of the bimodal mechanism of injury and patient characteristics. The patient should be assessed for life- and limb-threatening injuries in accordance with British Orthopaedic Association Standards of Trauma guidelines. Imaging is undertaken to understand configuration of the fracture, which is classified by the Schatzker classification. Definitive management of the fracture depends on the severity, ranging from conservative to surgical management. Surgery is required for more severe tibial plateau fractures to restore articular congruity, mechanical alignment, ligamentous stability and to permit early mobilisation. Medium-term functional outcome after tibial plateau fractures is generally excellent when anatomy and stability is restored. At least half of patients return to their original level of physical activity. Surgical management of tibial plateau fractures is not without complication. Risk factors include postoperative arthritis, bicondylar and comminuted fractures, meniscal removal, instability, malalignment and articular incongruity. Tibial plateau fractures account for 1% of all fractures, and typically occur either as a fragility fracture or secondary to a high-energy impact. These latter injuries are associated with extensive soft tissue injury, life- and limb-threatening complications and long-term sequelae. While outcomes are generally good, severe injuries are at higher risk of infection and post-traumatic arthritis requiring knee arthroplasty. This article considers the anatomy, diagnosis and evidence-based management strategies for tibial plateau fracture.

A comparison of patient-reported outcome measures (PROMs) between short and conventional stem hip replacements: a systematic review and meta-analysis.

INTRODUCTION: Short stem hip replacements may allow preservation of proximal bone stock and minimise soft tissue disruption, easing future revision surgery. However patient satisfaction with these implants must be determined before widespread use. We aimed to compare patient reported outcome measures (PROMs) between short and conventional stem hip replacements. METHODS: A systematic review was conducted according to PRISMA guidelines for studies comparing short and conventional stem hip replacements with validated PROMs. Meta-analyses were performed for studies reporting Harris Hip and WOMAC scores. Study bias was assessed with the Cochrane Risk of Bias tool and Newcastle-Ottawa Scale. RESULTS: 24 studies, incorporating 2593 total hip replacements were included for qualitative analysis. 17 studies were included in the meta-analyses. Of the 7 excluded, 1 study reported the Japanese Orthopaedic Association score and 2 others reported the Oxford Hip score. All three showed no difference between the stems. A meta-analysis of 17 studies reporting Harris hip scores showed no statistically significant difference between short and conventional stems (standard mean difference (SMD) -0.06, 95% CI -0.20-0.07, p = 0.35). 6 studies reported WOMAC scores with higher scores indicating worse outcome. No difference was seen between the two groups (SMD 0.21, 95%CI, -0.01-0.42, p = 0.06). 4 studies reported higher WOMAC scores as better. Once again, a meta-analysis showed no statistically significant difference between the stems (SMD 0.28, 95% CI -0.07-0.63, p = 0.12). CONCLUSIONS: Our systematic review showed no difference in PROMs between short and conventional stem total hip replacements. This is in keeping with previous evidence but is a more comprehensive analysis. Short stems may have an important role in younger individuals as they allow preservation of proximal femoral bone, minimal access surgery and are amenable to abnormal anatomy. The current literature is hindered by non-uniform methodologies and outcome assessments across studies. Further, standardised, high quality evidence is required before widespread changes in practice.

Gait after Birmingham Hip Resurfacing: an age-matched controlled prospective study.

AIMS: The aim of this study was to assess the functional gain achieved following hip resurfacing arthroplasty (HRA). PATIENTS AND METHODS: A total of 28 patients (23 male, five female; mean age, 56 years (25 to 73)) awaiting Birmingham HRA volunteered for this prospective gait study, with an age-matched control group of 26 healthy adults (16 male, ten female; mean age, 56 years (33 to 84)). The Oxford Hip Score (OHS) and gait analysis using an instrumented treadmill were used preoperatively and more than two years postoperatively to measure the functional change attributable to the intervention. RESULTS: The mean OHS improved significantly from 27 to 46 points (p < 0.001) at a mean of 29 months (12 to 60) after HRA. The mean metal ion levels at a mean 32 months (13 to 60) postoperatively were 1.71 (0.77 to 4.83) µg/l (ppb) and 1.77 (0.68 to 4.16) µg/l (ppb) for cobalt and chromium, respectively. When compared with healthy controls, preoperative patients overloaded the contralateral good hip, limping significantly. After HRA, patients walked at high speeds, with symmetrical gait, statistically indistinguishable from healthy controls over almost all characteristics. The control group could only be distinguished by an increased push-off force at higher speeds, which may reflect the operative approach. CONCLUSION: Patients undergoing HRA improved their preoperative gait pattern of a significant limp to a symmetrical gait at high speeds and on inclines, almost indistinguishable from normal controls. HRA with an approved device offers substantial functional gains, almost indistinguishable from healthy controls. Cite this article: Bone Joint J 2019;101-B:1423-1430.

Fibular nails for open and closed ankle fractures: Results from a non-designer level I major trauma centre.

AIM: To evaluate the outcome of a fibular nail in the treatment of open and closed unstable ankle fractures in a non-designer centre. METHODS: In a retrospective cohort study, a total of 39 ankle fractures (14 open and 25 closed) treated with a locking fibular nail were evaluated between 2012 and 2015 in a non-designer level I major trauma centre. Post-operative radiographs were analysed to assess the quality of reduction (McLennan and Ungersma marking system), fracture union and complications. Three patient reported outcome scores (Olerud and Molander score (OMAS), American Association of Orthopaedic Surgeons (AAOS) foot and ankle score and 12-Item Short Form Survey (SF-12)) were collected to obtain an overall measure of the patient's physical and mental outcome. RESULTS: The adequacy of reduction data was available for 38 of 39 cases; 33 (87%) achieved good, 3 (8%) fair and 2 (5%) poor ratings, based on the McLennan and Ungersma marking system. Thirty-five (12 open and 23 closed) patients were available for initial follow-up. Five (14.3%) of 35 had documented complications (2 of 12 in the open cohort and 3 of 23 in the closed cohort). All fibular fractures treated with the fibular nail went on to unite. Twenty-three (66%) of 35 patients were available at 1-year follow-up for measurement of objective outcome. The combined mean OMAS for both groups was 53.7 (0-85) with statistically better results (59.5 (25-85) vs. 37.3 (0-75)) in favour of the closed versus open injuries, respectively. The mean AAOS score was also statistically better for the closed group than the open, 70.3 (30-95) versus 46.6 (20-77), respectively. The mean SF-12 score (physical component) was 40 (21.6-52.4) in the closed group versus 36.1 (19.4-51.5) in the open group; the mean mental component was 42.5 (26.6-54.3) in the closed group versus 38.8 (28.4-60.5) in the open group, these however were not statistically different. CONCLUSION: Fibular nails are an effective alternative for the treatment for both closed and open unstable ankle fractures with soft tissue compromise.

Patient-specific guides improve hip arthroplasty surgical accuracy.

The role of patient-specific (PS) technology in total hip arthroplasty remains relatively unexplored. We asked whether PS guides: (1) Reduced average surgical errors? (2) Reduced outlier error frequencies? (3) Could predict the size of implants used? A single surgeon implanted femurs using either standard or PS guides and was blinded to the pre-operative plans. There were significant differences in median leg length errors between standard (3.3 mm) and PS groups (1.4 mm), U = 110, z = -2.3, p = 0.02. In contrast to the PS group, the standard group had significantly more outlier errors and frequently undersized implants. PS guides improve hip arthroplasty surgical accuracy.Abbreviations: PS: patient specific; THA: total hip arthroplasty; LLD: leg length discrepancies; HRA: hip resurfacing arthroplasty.

Use of ketamine sedation for the management of displaced paediatric forearm fractures.

AIM: To determine if ketamine sedation is a safe and cost effective way of treating displaced paediatric radial and ulna fractures in the emergency department. METHODS: Following an agreed interdepartmental protocol, fractures of the radius and ulna (moderately to severely displaced) in children between the age of 2 and 16 years old, presenting within a specified 4 mo period, were manipulated in our paediatric emergency department. Verbal and written consent was obtained prior to procedural sedation to ensure parents were informed and satisfied to have ketamine. A single attempt at manipulation was performed. Pre and post manipulation radiographs were requested and assessed to ensure adequacy of reduction. Parental satisfaction surveys were collected after the procedure to assess the perceived quality of treatment. After closed reduction and cast immobilisation, patients were then followed-up in the paediatric outpatient fracture clinic and functional outcomes measured prospectively. A cost analysis compared to more formal manipulation under a general anaesthetic was also undertaken. RESULTS: During the 4 mo period of study, 10 closed, moderate to severely displaced fractures were identified and treated in the paediatric emergency department using our ketamine sedation protocol. These included fractures of the growth plate (3), fractures of both radius and ulna (6) and a single isolated proximal radius fracture. The mean time from administration of ketamine until completion of the moulded plaster was 20 min. The mean time interval from sedation to full recovery was 74 min. We had no cases of unacceptable fracture reduction and no patients required any further manipulation, either in fracture clinic or under a more formal general anaesthetic. There were no serious adverse events in relation to the use of ketamine. Parents, patients and clinicians reported extremely favourable outcomes using this technique. Furthermore, compared to using a manipulation under general anaesthesia, each case performed under ketamine sedation was associated with a saving of £1470, the overall study saving being £14700. CONCLUSION: Ketamine procedural sedation in the paediatric population is a safe and cost effective method for the treatment of displaced fractures of the radius and ulna, with high parent satisfaction rates.

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 push-off 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.

Validation of an ear-worn sensor for gait monitoring using a force-plate instrumented treadmill.

A force-plate instrumented treadmill (Hp Cosmos Gaitway) was used to validate the use of a miniaturised lightweight ear-worn sensor (7.4 g) for gait monitoring. Thirty-four healthy subjects were asked to progress up to their maximum walking speed on the treadmill (starting at 5 km/h, with 0.5 km increments). The sensor houses a 3D accelerometer which measures medio-lateral (ML), vertical (VT) and anterior-posterior (AP) acceleration. Maximum signal ranges and zero crossings were derived from accelerometer signals per axis, having corrected for head motion and signal noise. The maximal force, measured by the instrumented treadmill correlated best with a combination of VT and AP acceleration (R-squared = 0.36, p = 0), and combined VT, ML, and AP acceleration (R-squared=0.36, p = 0). Weight-acceptance peak force and impulse values also correlated well with VT and AP acceleration (Weight acceptance: R-squared = 0.35, p = 0, Impulse: 0.26, p = 0), and combined VT, ML, and AP acceleration (Weight acceptance: R-squared = 0.35, p = 0, Impulse: 0.26, p=0). Zero crossing features on the ML axis provided an accurate prediction of the gait-cycle, with a mean difference of 0.03s (-0.01, 0.05 confidence intervals).