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We evaluated the short- to mid-term results of an unconstrained total ankle prosthesis (S.T.A.R.) with uncemented fixation. Seventy-nine consecutive ankle replacements were performed in 76 patients between 1996 and 2000. The initial diagnosis was posttraumatic osteoarthrosis in 51 cases (64%), primary osteoarthrosis in 14 cases (18%), and systemic joint affection in 14 cases (18%). Although 29 revision operations were necessary, all implants became fix, and no implants have been removed. At the last follow-up control, 38 patients (62%) were very satisfied, 20 patients (33%) were satisfied, and 3 patients (5%) were satisfied with reservations. The obtained range of motion was 35 degrees (range, 15 to 55 degrees), with a maximal plantarflexion of 27 degrees (range, 15 to 45 degrees) and dorsiflexion of 8 degrees (-3 to 20 degrees). The AOFAS-Hindfoot-Score of the 61 patients scored 84 points (range, 51 to 100 points). After settling of the implants within 6 weeks, no migration was noted in any case, and all implants were considered to be stable. The favorable results were considered to be a result of the mechanical properties of the S.T.A.R. total ankle prosthesis that allow for unconstrained motion. The rate of revisions, however, was too high, and it was considered to be a result of the design of tibial and talar component, the tibial fixation and the poor instrumentation. Nevertheless, total ankle replacement was shown to be a viable alternative to ankle arthrodesis. A longer follow-up is, however, mandatory to evaluate the long-term prognosis.
From 1985 to 1987 a total of 95 ankle arthrodesis were performed. The retrospective study showed in most cases a bony healing within 14 weeks with a complication rate of 20%, due to reduced conditions of the soft tissue. The follow up examination of 52 patients showed a good to very good result in 48 cases. Nearly 70% of the patients did not use orthopaedic made-to-measure shoes at the time of follow up. Only 4% were dissatisfied with this procedure. Therefore the arthrodesis of the ankle should be preferred in comparison to the arthroplastik.
The axis of the talo-crural joint was analysed by roentgen stereophotogrammetry in eight healthy volunteers. Examinations were performed at 10 degrees increments of flexion and pronation/supination of the foot as well as medial and lateral rotation of the leg. Results indicate that the talo-crural joint axis changes continuously throughout the range of movement. In dorsiflexion it tended to be oblique downward and laterally. In rotation of the leg, the axis took varying inclinations between horizontal and vertical. All axes in each subject lay close to the midpoint of a line between the tips of the malleoli. Our study indicates that the talo-crural joint axis may alter considerably during the arc of motion and differ significantly between individuals. This prompts caution in the use of hinge axes in orthoses and prostheses for the ankle.
Between 1980 and 1984, 268 patients with recent ankle ligament ruptures were treated with primary surgical repair at the 2nd Department of Trauma Surgery, University of Vienna. The decision for immediate operative treatment was based on clinical findings as well as on a positive stress roentgenogram. Ligament ruptures were diagnosed if the talar tilt on the injured side exceeded that on the uninjured side by 5 degrees or more or if the ventral subluxability of the talus was more than 5 mm compared with the uninjured side. One hundred twenty-two patients were followed up for 2-6 years after operation; follow-up included physical examination as well as standardized and stress roentgenograms. Good results were obtained in 80% of cases, moderate results in 17%, and poor results in 3%. All of the poor results were due to persistent radiological instability and/or arthrotic joint degeneration. The incidence of infection was 1.5%.
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As clinicians become more involved in preventative screening, assessment, and treatment of newborns and infants, an increasing need exists for quantitative, normal joint range-of-motion data for this population. We used a goniometer to assess in 40 healthy, full-term newborns the following passive ranges of motion: hip extension, knee extension, ankle plantar flexion, ankle dorsiflexion, and the popliteal angle. Every infant except one lacked full extension at both the hip and the knee. Plantar flexion was generally limited, but dorsiflexion was unlimited. Popliteal angle measurements showed the greatest amount of variation among the infants. Pearson correlation coefficients indicated that those infants with greater dorsiflexion tended to have less plantar flexion, and those with a greater limitation of knee extension measured with the hip extended tended also to have a smaller popliteal angle. Intrauterine position and newborn flexor tone are discussed as possible contributing factors to the results obtained in this study.
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Arthrodesis is currently the treatment of choice for symptomatic degenerative arthropathy of the ankle. Thirty-seven patients underwent arthrodesis for post-traumatic disorders using either a Hoffmann external fixator or a Calandruccio frame. There was degenerative joint disease in 19 (51%), septic arthritis in 11 (30%), severe comminution in five (14%), and uncontrollable equinus in two (5%). The patients were divided into two groups. Twenty-six (70%) were considered to have sustained high energy open or comminuted injuries and 11 (30%), low energy injuries. Twenty-nine (78%) achieved a radiologic fusion following one operation. Four eventually united with further surgery for a final arthrodesis rate of 89%. In the high energy group 18 of 26 (69%) achieved primary fusion. Four united with additional surgery for a final arthrodesis rate of 85%. Two of these required subsequent amputations and two others, a triple arthrodesis which also failed to control chronic pain. Thus, a total of 18 of the 26 patients (69%) achieved a successful result. Also included in the high energy group were three patients with uncontrolled sepsis who underwent amputation before union occurred and one with a painful non-union. All 11 of the patients (100%) who originally sustained low energy injuries achieved a successful arthrodesis. The most common complication was in pin tract infection requiring incision, drainage, and oral antibiotics in 16 patients (43%). None of these progressed to chronic osteomyelitis.
The arthroscopy is an attractive method for the diagnosing and treatment of injured joint structures in contemporary sport medicine. Vascular complications of this technique are very rare but generally extremely dangerous for the extremity salvage. We describe a rare case of the pedal artery pseudo aneurysm after ankle arthroscopy and the treatment of this complication.
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In the present work, a generic model for the prediction of moment-angle characteristics in individual human skeletal muscles is presented. The model's prediction is based on the equation M = V x Lo(-1)sigma c cos phi x d, where M, V, and Lo are the moment-generating potential of the muscle, the muscle volume and the optimal muscle fibre length, respectively, and sigma, phi and d are the stress-generating potential of the muscle fibres, their pennation angle and the tendon moment arm length, respectively, at any given joint angle. The input parameters V, Lo, sigma, phi and d can be measured or derived mechanistically. This eliminates the common problem of the necessity to estimate one or more of the input parameters in the model by fitting its outcome to experimental results often inappropriate for the function modelled. The model's output was validated by comparisons with the moment-angle characteristics of the gastrocnemius (GS) and tibialis anterior (TA) muscles in six men, determined experimentally using voluntary contractions at several combinations of ankle and knee joint angles for the GS muscle and electrical stimulation for the TA muscle. Although the model predicted realistically the pattern of moment-angle relationship in both muscles, it consistently overestimated the GS muscle M and consistently underestimated the TA muscle M, with the difference gradually increasing from dorsiflexion to plantarflexion in both cases. The average difference between predicted and measured M was 14% for the GS muscle and 10% for the TA muscle. Approximating the muscle fibres as a single sarcomere in both muscles and failing to achieve complete TA muscle activation by electrical stimulation may largely explain the differences between theory and experiment.
Varus deformity is a well known problem in the treatment of chronic lateral ankle instability. Surgical correction is recommended occasionally. The goal of this study was to show the effect of a calcaneal Dwyer osteotomy in patients suffering from a functional instability. We examined 6 patients, who underwent 7 calcaneal osteotomies. Postoperatively all patients maintained stability. No recurrence of a supination trauma was observed.
During maximal efforts, antagonistic activity can significantly influence the joint moment. During maximal voluntary "isometric" contractions, certain joint rotation can not be avoided. This can influence the estimation of the antagonistic moment from the EMG activity. Our study aimed to quantify the influence on the calculated agonistic moment produced during maximal voluntary isometric plantarflexions (a) when estimating antagonistic moments at different ankle angles and (b) when placing the EMG electrodes at different portions over the m. tibialis anterior. Ten subjects performed maximal voluntary isometric plantarflexions at 90 degrees ankle angle. In order to estimate the antagonistic moment, submaximal isometric dorsiflexions were performed at various ankle angles. Moment and EMG signals from mm. triceps surae and tibialis anterior were measured. The RMS differences between plantarflexors moment calculated considering the antagonistic cocontraction estimated at the same ankle angle at which the maximal plantarflexion moment was achieved and at different ankle angles ranged from 0.10 to 2.94 Nm. The location of the electrodes led to greater RMS differences (2.35-5.18 Nm). In conclusion, an angle 10 degrees greater than the initial plantarflexion angle is enough to minimize the effect of the change in length of the m. tibialis anterior during the plantarflexion on the estimation of the plantarflexors moment. The localisation of the electrodes over the m. tibialis anterior can influence the estimation of its cocontraction during maximal plantarflexion efforts.
We report on new medicomechanic equipment designed for the improvement of the venous reflux in the lower extremity. It may be employed as postoperative prophylaxis against thrombosis and in the treatment of secondary manifestations based on venous insufficiency, as well as with pathological changes caused by ankylosis of the ankle.
In 1997 six patients with posttraumatic ankle arthritis aged 54 (45-71) years were treated with a LINK S.T.A.R. ankle prothesis. The average follow up was 29 (21-36) months. Results were evaluated according to the ankle score of H. Kofoed [7]. Two patients had an excellent outcome and 1 patient had a fair result. In three patients secondary arthrodesis had to be performed, due to loosening of the implant. Based on our experiences we cannot recommend this implant for patients with posttraumatic arthritis at this time.