Biomedical subjects
T Benkalfate
Publications and source records attributed to T Benkalfate.
[Femoral loosening of total hip prosthesis caused by pseudarthrosis resulting from trochanterotomy].
PURPOSE OF THE STUDY: This survey of 48 cases of trochanteric non-union in THR showed that this complication had not only functional consequences (one patient out of three complains of some instability and mild pain) but may also lead to stem loosening (3/48) through an original mechanism. The movements of the trochanter produce wear debris, mainly from the broken metal wires fixing the trochanter (and from rubbing of the cement on the femoral side of the osteotomy). These debris create an osteolytic granuloma between the proximal lateral endocortex and the cement, which extends progressively to the distal tip of the stem. MATERIAL AND METHODS: A continuous series of 446 cemented Charnley type prostheses by the trans trochanteric approach showed 48 trochanteric non unions (11 per cent) which were examined at an average follow up of 6.5 years. Six patients were reoperated for important hip instability. Ten who suffered only from moderate instability were not reoperated on. 32 were asymptomatic and therefore where not reoperated, but 3 of them suffered from severe femoral loosening after 6 years and required revision. RESULTS: These cases of loosening due to trochanteric non union were characterized by: clinical patterns: they occurred only after 6 years, in active patients under 50; radiological aspects: osteolysis was initially limited to the lateral cortex (without any calcar resorption or radio lucency around the cup) analysis by electronic microscopy of the granuloma (harvested at revision) showed metallic debris (under 1 mu) inside macrophages, with some cement particles (secondary to the loosening). DISCUSSION: Mechanism of loosening These cases of loosening differ from those due to granuloma caused by wear debris of PE and from granulomas resulting from deterioration of the cement around the femoral stem, which both occur only much later with the Charnley prostheses. In our consecutive series of 32 cases of Charnley THR in young active patients with an average follow up of 9.5 years, the only cases of femoral loosening observed were related to trochanteric non unions. Hyposolicitation by trochanteric non union does not lead either to bone resorption or to stem loosening, as we could notice in a series of moderately active patients over 60 with loose non unions. Loosening due to trochanteric non unions was only observed in active patients with tight non unions, as the patient's activity and contact of the surfaces increase rubbing and wear of metal wires. Prevention of trochanteric non union. Despite attentive care to fixation of trochanter there is an unavoidable percentage of non union even in simple cases (3 to 4 per cent according to Charnley). Therefore we advocate this technique only when a large exposition is necessary (revisions, THR for dislocation etc..) CONCLUSIONS: Trochanteric non union may lead to stem loosening after 6 years in active patients under 50. Therefore we recommend: to restrict the use of the trochanteric approach to some difficult THR: revisions, prostheses for dislocation, etc... to reoperate patients under 50 with a trochanteric non union: if it is clinically symptomatic if a progressive granuloma of the lateral cortex, even though asymptomatic, appears.
['Endolock' femoral and tibial nail. Concept and laboratory studies].
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["Endolock" locking femoral nail without radiologic imaging (66 cases)].
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[Transtrochanteric rotation osteotomies for osteonecrosis of the femoral head. Apropos of 20 cases].
PURPOSE OF THE STUDY: Twenty consecutive rotation osteotomies for idiopatic necrosis of the femoral head were reviewed with an average follow-up of 6,5 years, in order to evaluate an original technique (which uses a nail plate for rotation and fixation of the fragments), and to determine the middle term results (and therefore indications) of anterior and posterior rotation osteotomies. MATERIALS AND METHODS TECHNIQUE: rotations were achieved by rotating the femoral head with the nail of the nail plate, and without dissection of the posterior vascular bundle. We performed 16 anterior rotation osteotomies (according to Sugioka, with an average rotation of 52 degrees) and 4 posterior rotation osteotomies (described by Kempf, with an average rotation of 77 degrees). Only two patients were lost after 2 years follow-up (with good result), and the radio-clinical outcome of 18 operations at 5 years was known. RESULTS: Global results were : 7 failures, 3 fair and 10 very good or good. In the 4 posterior rotations (Kempf) we achieved 4 very good results, even in Ficats stage 3. In the 16 anterior rotations we could in all cases obtain, on the hip in extension, an almost complete discharge of the necrotic zone, as after osteotomy it was no more in front of the acetabular major bearing zone (defined as an angle of 40 degrees around the apex of the femoral head on the lateral Lequesne view). We obtained 6 good and very good results, 3 fair, and 7 failures requiring a THR. There were 2 factors of poor prognosis : Stage of the necrosis, as we observed 4 failures in the 4 Ficat's stage 3, and only 3 failures in the 12 stage 2. Depth of the necrosis, as we achieved 6 very good and good results and 1 poor in the 7 cases when it was no more than 1/3 of the head diameter. But in the 9 cases where depth was over one third there were 3 fair and 6 poor results. DISCUSSION: Our technique proved to be reliable as it achieved the rotation planned before operation (only one hypo-correction of 15 degrees) and bone fusion, allowing full weight bearing at 3 months in all cases. No extension of the necrotic area was observed. Posterior rotation osteotomy was followed by long term favorable results, may be because it achieves an anatomic discharge of the necrotic zone not only when the hip is in extension, but also when the hip is flexed. Anterior rotation is only recommended when : a rotation not exceeding 60 degrees (therefore without risks for the posterior bundle) allows a discharge of the necrotic zone when the hip is in extension. The necrosis is stage 2. In Stage 3 a progressive arthritis may occur as, in hip flexion, the necrotic sector of the non spherical head comes in front of the acetabular major bearing zone. The depth of the necrosis does not exceed 1/3 of the femoral head, such as in cases of a very large necrosis, mechanical degradation of the non necrotic part of the head may occur, even if discharge of the necrosis is achieved. CONCLUSION: Transtrochanteric rotation osteotomy may delay of a decade or more the occurring of osteoarthritis, if its indications are restricted to patients under 40, suffering from idiopatic necrosis. In our series Sugioka osteotomy gave good results in stage 2 when necrosis depth was no more than 1/3 of the head diameter. Posterior osteotomy allows a better discharge of the necrotic zone and thus may be proposed in less restricted conditions.
[An unusual dislocation of the elbow: convergent dislocation].
A case of dislocation of the elbow, combining convergent dislocation of the proximal radio-ulnar joint with posterior dislocation of the ulno-humeral joint was reported. This particular combination has not, to the knowledge of the authors, been reported previously. Diagnosis was based on anterioposterior X ray of the joint associated with a clinical finding of a loss of supination following reduction of the ulno-humeral joint. This unusual lesion has to be recognised for a missed diagnosis may lead to compromise of the result in the long term.