[Aseptic loosening of total ankle replacement : One-stage revision ankle arthroplasty]. / Aseptische Lockerung einer OSG­Endoprothese : Einzeitiger Prothesenwechsel.

OBJECTIVE: To revise one or both loosened prosthesis components, to achieve postoperative pain relief, and preserve ankle range of motion. INDICATIONS: Aseptic loosening of the tibial and/or talar ankle prosthesis components without substantial bone defect of the tibial or talar bone stock. CONTRAINDICATIONS: General surgical or anesthesiological risks, infections, critical soft tissue conditions, nonmanageable hindfoot instability, neurovascular impairment of the lower extremity, neuroarthropathy (e. g. Charcot arthropathy), substantial nonreconstructable osseous defects with or without cysts on the tibial and/or talar side, non-compliance, patients with primary total ankle replacement (TAR) using intramedullary fixation (stem fixation), patients with severely reduced bone quality, insulin-dependent diabetes mellitus, smoking, unrealistic patient expectations, patients with high activity in sports. SURGICAL TECHNIQUE: Exposure of the ankle joint using the previous incision (anterior or lateral transfibular approach). Mobilization and removal of loosened prosthesis component. Careful debridement of bone stock at bone-prosthesis interface. Determination of prosthesis component size. Implantation of definitive prosthesis components. Wound closure in layers. POSTOPERATIVE MANAGEMENT: A soft wound dressing is used. Thromboprophylaxis is recommended. Patient mobilization starts at postoperative day 1 with 15 kg partial weight bearing using a stabilizing walking boot or cast for 6 weeks. Following clinical and radiographic follow-up at 6 weeks, full weight bearing is initiated gradually. RESULTS: Between January 2007 and December 2012 a one-stage revision TAR was performed in 14 patients with a mean age of 52.7 ± 12.0 years (29.8-70.5 years). The indication for revision surgery was aseptic loosening of one or both prosthesis components. The mean time between the initial TAR and revision surgery was 5.9 ± 2.9 years (2.0-11.5 years). In 2 patients a tibiotalocalcaneal arthrodesis was performed due to painful aseptic loosening of revision TAR. In all patients a significant pain relief was observed.

Surgical procedures in patients with haemophilic arthropathy of the ankle.

BACKGROUND: In haemophilia, the ankle joint is one of the most common and earliest joints affected by recurrent bleeding, commonly resulting in end-stage ankle osteoarthritis during early adulthood. The surgical treatment of haemophilic ankle arthropathy is challenging. PURPOSE: This review aims to highlight the literature addressing clinical outcomes following the most common approaches for different stages of haemophilia-induced ankle osteoarthritis: arthroscopic debridement, joint distraction arthroplasty, supramalleolar osteotomies, total ankle replacement, and ankle arthrodesis. METHODS: A systematic literature review was performed using established medical literature databases. The following information was retrieved from the literature: patients' demographics, surgical technique, duration of follow-up, clinical outcome including pain relief and complication rate. RESULTS: A total of 42 clinical studies published between 1978 and 2015 were included in the systematic literature review. Eight and 34 studies had prospective and retrospective design, respectively. The most common studies were level IV studies (64.3%). DISCUSSION: The orthopaedic treatment of patients with haemophilic ankle osteoarthritis is often challenging and requires complete and careful preoperative assessment. In general, both joint-preserving and joint non-preserving procedure types can be performed. All specific relative and absolute contraindications should be considered to achieve appropriate postoperative outcomes. CONCLUSION: The current literature demonstrated that orthopaedic surgeries, with appropriate indication, in patients with haemophilic ankle arthropathy result in good postoperative results comparable to those observed in non-haemophiliacs. The surgical treatment should be performed in a setting with the ability to have multidisciplinary management, including expertise in haematology.

Subchondral bone remodeling is related to clinical improvement after joint distraction in the treatment of ankle osteoarthritis.

OBJECTIVE: In osteoarthritis (OA), subchondral bone changes alter the joint's mechanical environment and potentially influence progression of cartilage degeneration. Joint distraction as a treatment for OA has been shown to provide pain relief and functional improvement through mechanisms that are not well understood. This study evaluated whether subchondral bone remodeling was associated with clinical improvement in OA patients treated with joint distraction. METHOD: Twenty-six patients with advanced post-traumatic ankle OA were treated with joint distraction for 3 months using an Ilizarov frame in a referral center. Primary outcome measure was bone density change analyzed on computed tomography (CT) scans. Longitudinal, manually segmented CT datasets for a given patient were brought into a common spatial alignment. Changes in bone density (Hounsfield Units (HU), relative to baseline) were calculated at the weight-bearing region, extending subchondrally to a depth of 8mm. Clinical outcome was assessed using the ankle OA scale. RESULTS: Baseline scans demonstrated subchondral sclerosis with local cysts. At 1 and 2 years of follow-up, an overall decrease in bone density (-23% and -21%, respectively) was observed. Interestingly, density in originally low-density (cystic) areas increased. Joint distraction resulted in a decrease in pain (from 60 to 35, scale of 100) and functional deficit (from 67 to 36). Improvements in clinical outcomes were best correlated with disappearance of low-density (cystic) areas (r=0.69). CONCLUSIONS: Treatment of advanced post-traumatic ankle OA with 3 months of joint distraction resulted in bone density normalization that was associated with clinical improvement.

The effect of accuracy of implantation on range of movement of the Scandinavian Total Ankle Replacement.

When performing the Scandinavian Total Ankle Replacement (STAR), the positioning of the talar component and the selection of mobile-bearing thickness are critical. A biomechanical experiment was undertaken to establish the effects of these variables on the range of movement (ROM) of the ankle. Six cadaver ankles containing a specially-modified STAR prosthesis were subjected to ROM determination, under weight-bearing conditions, while monitoring the strain in the peri-ankle ligaments. Each specimen was tested with the talar component positions in neutral, as well as 3 and 6 mm of anterior and posterior displacement. The sequence was repeated with an anatomical bearing thickness, as well as at 2 mm reduced and increased thicknesses. The movement limits were defined as 10% strain in any ligament, bearing lift-off from the talar component or limitations of the hardware. Both anterior talar component displacement and bearing thickness reduction caused a decrease in plantar flexion, which was associated with bearing lift-off. With increased bearing thickness, posterior displacement of the talar component decreased plantar flexion, whereas anterior displacement decreased dorsiflexion.

Ankle fractures in patients with diabetes mellitus.

Diabetes mellitus is considered an indicator of poor prognosis for acute ankle fractures, but this risk may be specific to an identifiable subpopulation. We retrospectively reviewed 42 patients with both diabetes mellitus and an acute, closed, rotational ankle fracture. Patients were individually matched to controls by age, gender, fracture type, and surgical vs non-surgical treatment. Outcomes were major complications during the first six months of treatment. We contrasted secondarily 21 diabetic patients with and 21 without diabetic comorbidities. Diabetic patients and controls did not differ significantly in total complication rates. More diabetic patients required long-term bracing. Diabetic patients without comorbidities had complication rates equal to their controls. Diabetic patients with comorbidities had complications at a higher rate (ten patients; 47%) than matched controls (three patients; 14%, p = 0.034). A history of Charcot neuroarthropathy led to the highest rates of complication. An increased risk of complications in diabetic patients with closed rotational fractures of the ankle are specific to a subpopulation with identifiable related comorbidities.

The blood supply of the common peroneal nerve in the popliteal fossa.

We investigated the blood supply of the common peroneal nerve. Dissection of 19 lower limbs, including six with intra-vascular injection of latex, allowed gross and microscopic measurements to be made of the blood supply of the common peroneal nerve in the popliteal fossa. This showed that a long segment of the nerve in the vicinity of the fibular neck contained only a few intraneural vessels of fine calibre. By contrast, the tibial nerve received an abundant supply from a constant series of vessels arising directly from the popliteal and posterior tibial arteries. The susceptibility of the common peroneal nerve to injury from a variety of causes and its lack of response to operative treatment may be explained by the tenuous nature of its intrinsic blood supply.

The effect of agility ankle prosthesis misalignment on the peri-ankle ligaments.

In the Agility total ankle replacement system, motion is constrained by the implant's articulating surfaces and the peri-ankle ligaments. The effects of plausibly occurring implant malpositioning on peri-ankle ligament functional extension during walking were explored in this study. The intent was to determine whether certain ligaments could serve as guides to assist in proper component positioning at implantation. Using a cadaver preparation with simulated physiologic motion and loading, we monitored change of ligament length of the anterior talofibular, posterior talofibular, calcaneofibular, and tibiocalcaneal ligaments resulting from controlled malpositioning of the tibial component relative to a neutral position. During a simulated walking cycle, effects of mediolateral and anterior/posterior translation, internal and external rotation, inversion and eversion, and elevation of the component were evaluated. In all cases, tibial component displacement from the neutral position caused atypical length change in one or more of the peri-ankle ligaments. In particular, anterior/posterior displacement significantly changed the lengthening behavior of all four tested ligaments. The anterior talofibular ligament was sensitive to transverse plane displacements, whereas the tibiocalcaneal ligament was sensitive to coronal plane displacements. For the Agility prosthesis, these two ligaments seem to be sensitive guides for tibial component positioning at implantation.

Pattern of diabetic neuropathic arthropathy associated with the peripheral bone mineral density.

The relationship between the bone mineral density (BMD) and Charcot arthropathy is unclear. Prospectively, 55 consecutive diabetic patients presenting with a Charcot arthropathy of the foot or ankle were classified as having a fracture, dislocation, or a combination fracture-dislocation pattern of initial destruction. In these groups we used dual-energy x-ray absorptiometry to compare the peripheral bone of the affected and unaffected limbs. The clinical data relating to diabetes and related major comorbidities and the site of the arthropathy (ankle, hindfoot, midfoot, forefoot) were also compared. There were 23 patients with a fracture pattern, 23 with a dislocation pattern, and nine with a combination. The age-adjusted odds ratio for developing a Charcot joint with a fracture pattern as opposed to a dislocation pattern in patients with osteopenia was 9.5 (95% confidence interval 2.4 to 37.4; p = 0.0014). Groups also differed as to the site of the arthropathy. Fracture patterns predominated at the ankle and forefoot whereas dislocations did so in the midfoot. Diabetic Charcot arthropathy of the foot and ankle differs according to the pattern of the initial destruction. The fracture pattern is associated with peripheral deficiency of BMD. The dislocation pattern is associated with a normal BMD.

Physiological responses to multiple speed treadmill walking for Syme vs. transtibial amputation--a case report.

PURPOSE: To date, there have been no longitudinal studies comparing walking at different levels of amputation. The objective of this study was to compare the self-selected walking velocity (SSWV) and selected physiologic variables during walking between a Syme and a later transtibial level of amputation for a single subject. Additional comparison was made between the SACH foot prosthesis and a dynamic response foot prosthesis. METHOD: A 35-year-old male with a traumatic Syme amputation later underwent elective transtibial amputation. SSWV and multiple speed treadmill walking tests (53.64, 67.05, 80.46, 93.87 and 107.28 m/min) were evaluated under three conditions (Syme prosthesis with SACH foot, transtibial prosthesis with SACH foot, and transtibial prosthesis with Flex-Foot). RESULTS: Walking with transtibial prosthesis showed minimal differences in oxygen consumption (0 - 5% reduction), heart rate response (0 - 1% reduction), or gait efficiency (0 - 5% improvement) across all speeds when compared with Syme prosthesis (both with SACH foot). However, the SSWV was 6 - 8% faster for the transtibial SACH foot. Walking with transtibial Flex-Foot required less cardiovascular demand than with transtibial SACH foot at higher speeds. CONCLUSIONS: In this case report, it seemed that transtibial amputation did not have adverse effects on selected physiological responses at a variety of walking speeds when compared to Syme amputation, and that the use of a dynamic response foot enhanced his gait performance. Further experimental studies involving more subjects with traumatic Syme and transtibial amputations are required to better understand the effect of these two levels of amputation on energy cost of walking.

[Prosthetic replacement of the upper ankle joint]. / Endoprothetischer Ersatz des oberen Sprunggelenks.

Results after total ankle arthroplasty in the 1970s and 1980s were poor. The outcomes of these surgeries deteriorated rather dramatically with time. Causes of failure were multifactorial, but the two main reasons for failure were constrained designs and cement fixation. Today, the design of total ankle arthroplasty is unconstrained and the fixation is uncemented. Total ankle arthroplasties are considered technically demanding procedures, with relatively high early postoperative complication rates. As yet, the ideal total ankle patient remains to be defined. Good alignment and ligamentous stability are essential. Osteonecrosis and profound osteoporosis are associated with poor results due to problems with bony fixation. Patients should be advised that the implant may fail and that this may require further surgery, including the potential need for an ankle fusion. The results of ankle fusions, although usually initially good, seem to deteriorate with time. Not uncommonly, patients frequently develop peritarsal degenerative joint disease several years after an ankle arthrodesis. Because of the associated pain and functional limitations that can follow ankle fusion, efforts to develop a workable total ankle replacement continue. At present, the long-term results of new designs are unknown. Today, total ankle arthroplasty should be limited to centers where patient volume and infrastructure allows critical review and prospective clinical trials to determine the factors leading to successful and unsuccessful outcomes.

Retrospective review of eighteen patients who underwent transtibial amputation for intractable pain.

BACKGROUND: Amputations are rarely performed solely for pain relief because of concerns regarding the persistence of pain and disability after the procedure. The purpose of this study was to assess the outcome of below-the-knee amputations performed to relieve intractable foot and ankle pain. METHODS: A chart review was conducted to identify all below-the-knee amputations that had been performed for the treatment of chronic foot and ankle pain by three orthopaedic foot and ankle specialists at three institutions. The inclusion criteria included (1) intractable foot or ankle pain as the surgical indication, (2) failure of maximal medical therapy, (3) failure of prior surgical reconstruction, and (4) a minimum follow-up period of twenty-four months after below-the-knee amputation. Patients with diabetes mellitus, peripheral vascular occlusive disease, or peripheral neuropathy were excluded. Each participant completed a two-part questionnaire with regard to the levels of disability, function, pain, and recreational activity both before and after the amputation. RESULTS: Twenty patients met the inclusion criteria, and eighteen completed the study. The study group included four women and fourteen men who had an average age of forty-two years (range, twenty-six to sixty-one years) and were followed for an average of forty-one months (range, twenty-five to eighty-five months) after the amputation. When asked whether they would have the below-the-knee amputation done again under similar circumstances, sixteen patients said yes, one was unsure, and one said no. The same distribution was observed when the patients were asked whether they were satisfied with the outcome: sixteen said yes, one was unsure, and one said no. Disability, pain, and recreational status were assessed with a 10-cm visual analog scale. After the amputation, the patients reported a decrease in both pain frequency (with the average score improving from 9.8 to 1.7; p < 0.0001) and pain intensity (with the average score improving from 8.4 to 2.6; p < 0.0001). Ten patients discontinued the use of narcotics, and seven decreased the level and/or dosage. Three patients worked before the amputation, and eight worked after the amputation. The average walking distance increased from 0.3 to 0.8 mile (p = 0.0034). CONCLUSION: In selected patients, a below-the-knee amputation may be a good salvage procedure for intractable foot and ankle pain that is unresponsive to all medical and local surgical reconstructive techniques.

Footwear affects the behavior of low back muscles when jogging.

Use of modified shoes and insole materials has been widely advocated to treat low back symptoms from running impacts, although considerable uncertainty remains regarding the effects of these devices on the rate of shock transmission to the spine. This study investigated the effects of shoes and insole materials on a) the rate of shock transmission to the spine, b) the temporal response of spinal musculature to impact loading, and c) the time interval between peak lumbar acceleration and peak lumbar muscle response. It was hypothesised that shoes and inserts a) decrease the rate of shock transmission, b) decrease the low back muscle response time, and c) shorten the time interval between peak lumbar acceleration and peak lumbar muscle response. Twelve healthy subjects were tested while jogging barefoot (unshod) or wearing identical athletic shoes (shod). Either no material, semi-rigid (34 Shore A), or soft (9.5 Shore A) insole material covered the force plate in the barefoot conditions and was placed as insole when running shod. Ground reaction forces, acceleration at the third lumbar level, and erector spinae myoelectric activity were recorded simultaneously. The rate of shock transmission to the spine was greater (p < 0.0003) unshod (acceleration rate: Means +/- SD 127.35 +/- 87.23 g/s) than shod (49.84 +/- 33.98 g/s). The temporal response of spinal musculature following heel strike was significantly shorter (p < 0.023) unshod (0.038 +/- 0.021 s) than shod (0.047 +/- 0.036 s). The latency between acceleration peak (maximal external force) and muscle response peak (maximal internal force) was significantly (p < 0.021) longer unshod (0.0137 +/- 0.022s) than shod (0.004 +/- 0.040 s). These results suggest that one of the benefits of running shoes and insoles is improved temporal synchronization between potentially destabilizing external forces and stabilizing internal forces around the lumbar spine.

Pneumatic bracing and total contact casting have equivocal effects on plantar pressure relief.

The purpose was to examine and compare plantar pressures produced in healthy subjects while wearing a running shoe (RS), total contact cast (TCC) and 'customized' pneumatic pre-fabricated walking brace (PWB). A repeated measures design was used to compare the plantar pressures recorded for three footwear types (RS, TCC, PWB) in two body regions (forefoot, heel). Nine healthy subjects walked at a self-selected walking pace on a motorized treadmill while wearing the RS, TCC and PWB (ordered randomization). Following a five-minute acclimatization period on the treadmill with each footwear device, plantar pressures were recorded from 84 constant gait speed and step length steps using the Pedar system of in-shoe array of capacitive sensors embedded in an insert. Mean spatially averaged peak plantar pressures were recorded for the metatarsal heads and heel region for each footwear device worn by each subject. A two-way analysis of variance with repeated measures and post-hoc Tukey tests analysed the data with a significance level of p=.05. The main effects of footwear (p=.005) and body region (p=.000), and interaction effect (body region x footwear device) (p=.000) were significant. Unloading of the forefoot was 63.72% and 58.77% for the TCC and PWB, respectively, whereas loading under the heel was increased 37.09% and 34.11% for the same two devices, respectively. Patients who develop neuropathic plantar ulcers in the forefoot region, but not in the heel region, may benefit from a reduction in plantar pressures by using either the TCC or a 'customized' PWB. An alternative footwear device still needs to be found for those patients with heel ulceration.

The compartments of the foot revisited. Rethinking the validity of cadaver infusion experiments.

Previous dye-infusion experiments on cadavers have suggested that the hindfoot should be divided into four muscle compartments including a newly described 'calcaneal' element containing quadratus plantae. Since there are no clinical data to support this proposed division, we re-examined the validity of the infusion experiment. We made infusions of dilute Omnipaque at a constant rate into flexor digitorum brevis of four cadaver feet. We monitored the spread of the infusate by real-time CT imaging and measured the pressures at the infusion site by side-ported needles. In all feet, the barrier between flexor digitorum brevis and quadratus plantae became incompetent at pressures of less than 10 mmHg. Pressure gradients in this range cannot be expected to affect tissue perfusion significantly and independently generate compartment syndromes. These results do not confirm those of previous studies carried out by uncontrolled and unmonitored injections made by hand. Injection studies in cadaver limbs can give dramatically different results depending upon the assumptions made when designing the experiment. The technique cannot adequately act as a model of the physiology of the compartment syndrome. As the existence of a physiologically significant compartmental boundary between flexor digitorum brevis and quadratus plantae is based solely on a cadaver infusion experiment the presence of a 'calcaneal' compartment has not been confirmed.

Compartmental divisions of the hand revisited. Rethinking the validity of cadaver infusion experiments.

The results of a cadaver dye-infusion experiment suggested that the hand has ten muscle compartments and that the volar interossei occupy a separate anatomical compartment from the adjacent dorsal interossei. This is not supported by clinical findings. With various minor modifications, we repeated the experiment, infusing Omnipaque into the second dorsal interosseus muscle of four cadaver hands. We used real-time CT imaging to monitor the spread of contrast medium and side-ported needles to measure compartmental pressures. In all four hands, the tissue barrier between dorsal and volar interossei became incompetent at pressures of less than 15 mmHg. Our data indicate that, although cadaver infusion studies can delineate potentially significant musculoskeletal barriers, their physiological relevance must be confirmed clinically.

First ray dorsal mobility in relation to hallux valgus deformity and first intermetatarsal angle.

The hypermobile first ray has been implicated as contributing to the cause and progression of hallux valgus deformity. Deformity of the hallux is often accompanied by an enlarged first intermetatarsal (IM 1-2) angle. It has been hypothesized that subjects having an abnormally large IM 1-2 angle have laxity of the first ray. Objectives of this study were to compare dorsal mobility of the first ray in subjects with hallux valgus to asymptomatic controls, and to investigate the relationship between dorsal mobility and the IM 1-2 angle. Fourteen subjects (age 23-81) with hallux valgus were matched by gender and age to control subjects. The IM 1-2 angle was measured from radiographs. A load-cell device measured dorsal mobility of the first ray under a standard load of 55 N. Pearson's correlation coefficient identified a marginal correlation (r = .51) between IM 1-2 angle and dorsal mobility. An independent t-test showed a statistically (P < 0.01) larger amount of dorsal mobility in the group of subjects having hallux valgus. Mobility of the first ray was increased in subjects with hallux valgus and a large IM 1-2 angle may be an indicator of increased dorsal mobility.

Long-term results following ankle arthrodesis for post-traumatic arthritis.

BACKGROUND: Ankle arthrodesis is considered by many to be the standard operative treatment for end-stage ankle arthritis; however, the long-term effect of ankle arthrodesis on other lower-extremity joints remains largely unknown. The purpose of this study was to perform a clinical and radiographic review to determine the effect of ankle arthrodesis on the development of osteoarthritis in other lower-extremity joints. METHODS: Twenty-three patients who had had an isolated ankle arthrodesis for the treatment of painful posttraumatic arthritis of the ankle were followed for a mean of twenty-two years (range, twelve to forty-four years) after the operation. Each completed standardized, self-reported outcome questionnaires (the Foot Function Index, Western Ontario and McMaster University Osteoarthritis Index [WOMAC], and Short Form-36 [SF-36]), was examined clinically by two of the investigators, and underwent complete radiographic examination of the knee, ankle, and foot bilaterally. The radiographic grade of osteoarthritis was determined for each joint, and the levels of overall activity limitation, pain, and disability were determined for each patient from the clinical findings and questionnaire information. RESULTS: Osteoarthritis of the ipsilateral subtalar (p<0.0001), talonavicular (p<0.0001), calcaneocuboid (p<0.0001), naviculocuneiform (p = 0.0012), tarsometatarsal (p = 0.0009), and first metatarsophalangeal joints (p = 0.0012) was consistently more severe than the osteoarthritis of those joints on the contralateral side. Osteoarthritis did not develop more frequently in the ipsilateral knee or lesser metatarsophalangeal joints than it did on the contralateral side. Significant differences between the two sides were found with regard to overall activity limitation (p<0.0001), pain (p<0.0001), and disability (p<0.0001), with the involved side consistently more symptomatic. CONCLUSIONS: To our knowledge, the present series represents the longest follow-up study of ankle arthrodesis to date. Our cohort of patients all had isolated post-traumatic ankle arthritis, and each underwent a successful isolated ankle arthrodesis. At a mean of twenty-two years, the majority of the patients had substantial, and accelerated, arthritic changes in the ipsilateral foot but not the knee. They were often limited functionally by foot pain. Although ankle arthrodesis may provide good early relief of pain, it is associated with premature deterioration of other joints of the foot and eventual arthritis, pain, and dysfunction.

Contribution of individual projections alone and in combination for radiographic detection of ankle fractures.

OBJECTIVE: We wanted to determine whether the standard three-view ankle radiographic series could be replaced by a two-view combination, and if so, which two-view combination (anteroposterior with lateral or mortise with lateral) would be superior. MATERIALS AND METHODS: During a 12-month period, we retrospectively reviewed 556 consecutive ankle radiographic studies consisting of anteroposterior, mortise, and lateral views. One hundred twenty patients with at least one ankle fracture were paired with 140 healthy control subjects. Each image in the three-view examination was separated and sorted by view and studied independently; all images were reviewed by two skeletal radiologists and two orthopedic surgeons. Each radiograph was evaluated for fracture of the medial, lateral, and posterior malleoli and the foot using a five-point confidence rating. Performance of each view and modeled two- and three-view combinations of views was evaluated with modified receiver operating characteristic analysis. RESULTS: The data provide little support for preferring either two-view combination (anteroposterior-lateral or mortise-lateral) for any type of fracture. The three-view combination does detect significantly more fractures than some two-view combinations in some locations, and there is a statistically significant cost in diagnostic accuracy for eliminating the anteroposterior or mortise view. CONCLUSION: Reducing the ankle radiographic series from three to two views would result in a small but significant decrease in the detection of fractures of the ankle and foot. Both two-view combinations are equivalent for fracture detection.

The reliability and validity of a first ray measurement device.

The need for measuring the mobility of the first ray has been identified. The purpose of this study was to test the reliability and validity of a device built to measure the relative vertical displacement of the first ray. Twenty fresh frozen cadaver feet were sampled (mean age of donor was 70+/-13 years). Dorsal mobility of the first ray was measured by device over three trials of repeated loading using 20 N, 35 N, 55 N and 85 N of force. Radiographs served as the criterion standard for validation of the device. Vertical displacement was measured from x-ray by a digitizing procedure that recorded movement of the first ray during loading. Reliability of the device assessed by intraclass correlation coefficients (ICC) was .98 with standard errors of the measurement calculated to be 0.35 mm. A correlation of agreement value of .97 was determined for the two methods of measurement. Analysis of variance testing found a significant interaction between force and method of measurement. Tukey post-hoc analysis found no difference (F<1.70) between the two methods of measuring first ray displacement in cadaver specimens when the force applied did not exceed 55 N. At 85 N of force (F = 10.05), unwanted movement of the second metatarsal caused the device to overestimate the amount of displacement that occurred specific to the first ray. This measure of first ray mobility should help clinicians and researchers to better investigate foot pathology resulting from faulty mechanics of the first ray.