Biomedical subjects
Publications and source records attributed to P P Sarangi.
Anterior knee pain in athletes is common and usually self limited. There should be a high index of suspicion and low threshold for special imaging in cases with acute onset and specific tenderness. The risk of propagation of stress fracture of the patella in athletes is highlighted. The case report presented illustrates the potential sequence of events.
Sixty-three consecutive patients who had 82 Harris-Galante porous acetabular cups (HGP1) (Zimmer Inc, Warsaw, IN) implanted for the treatment of rheumatoid arthritis were prospectively assessed since 1986. At last examination, 12 patients (16 hips) had died, and 1 patient (1 hip) was lost to follow-up. A total of 65 hips in 50 patients were available for the latest review. The follow-up period was 6.8 years to 14 years (mean, 9.1 years). There had been 6 revisions: 1 for deep infection and 5 for polyethylene cup wear. Survivorship analysis for all failures estimated that 75% of hips would still be revision-free after 4558 days (12.5 years). Polyethylene wear has been identified in a further 7 cases at last examination. The average linear cup wear per year was 0.05 mm(range, 0.00-0.66 mm). There were no cases of acetabular loosening or acetabular migration. These results demonstrate the excellent durability of fixation of the HGP1 cups in patients with rheumatoid arthritis. However, a 32-mm head should probably not be used with this cup given the high associated incidence of polyethylene wear.
Splitting fractures of the humeral head are rare; part of the humeral head dislocates and the unfractured part remains attached to the shaft. We report eight cases in young patients. In five the diagnosis was made at presentation: three had minimal internal fixation using a superior subacromial approach, one had a closed reduction and one a primary prosthetic replacement. All five patients regained excellent function with no avascular necrosis at two years. In three the injury was initially unrecognised; two developed a painless bony ankylosis and one is awaiting hemiarthroplasty. It is important to obtain the three trauma radiographic views to diagnose these unusual fractures reliably. CT delineates the configuration of the fracture. In young patients open reduction and internal fixation seems preferable to replacement of the humeral head, since we have shown that the head is potentially viable.
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Forty-three patients who had undergone revision total knee arthroplasty following either primary, medial unicondylar arthroplasty (23 patients) or valgus tibial osteotomy (20 patients) for medial compartment osteoarthritis were reviewed. Although the two groups had similar knee scores and range of motion at review, six patients (30%) who had undergone prior tibial osteotomy suffered serious postoperative complications. Of these, four patients had a deep infection. It was felt that several factors were responsible, resulting largely from difficulties in gaining access to the lateral tibial plateau and subsequently causing impairment of wound vascularity and healing. In contrast, those patients undergoing revision of unicondylar prostheses did not experience wound healing problems, but it was noted that in half of the cases, there was significant bone loss from the medial tibial plateau.
THE PURPOSE OF THIS STUDY: was to investigate how deliberate slight undercorrection of varus deformities influenced the patterns of failure seen following medial unicompartmental knee replacements. METHODS: Between 1980 and 1989, 335 medial unicompartmental knee replacements were performed using the St George Sled prosthesis. The replacements were preformed so that the postoperative mechanical axis, as defined as the line joining the centre of the femoral head to the centre of the talus, passed medial to the centre of the knee joint and through the replaced medial compartment. The mean follow-up for these patients was 6.4 years (range of 2 to 12). By 1992, 33 of these cases had required revision. The radiographs and case notes of cases were available for study. RESULTS: There were no significant differences in the demographic details between those coming to revision and the successful group. Analysis of the post-operative alignments in the successful group revealed that the desired undercorrection was achieved in 73 per cent of cases. 2 per cent were left grossly undercorrected with their mechanical axis passing medially outside the medial compartment. In 20 per cent of cases the mechanical axis was almost fully restored passing through the centre of the knee. 4 per cent of cases had an overcorrection with the mechanical axis passing through the lateral compartment. Early failures (N = 11), classified as those cases in whom satisfactory result were never obtained, were primarily due to poor patient selection or to gross technical errors at surgery. Late failures (N = 22) were those that required revision for symptomatic failure after an initially successful primary arthroplasty and were due to progressive disease (N = 6), prosthetic failure (N = 22) were those that required revision for symptomatic failure after an initially successful primary arthroplasty and were due to progressive disease (N = 6), prosthetic failure (N = 10) and recurrent medial pain (N = 6). DISCUSSION: Patients who otherwise meet the criteria for medial unicompartmental replacement, usually have a mild degree of osteoarthritis in the lateral compartment. Suddenly loading the lateral compartment, by fully correcting a varus deformity, could accelerate the degenerative process in this compartment. Progressive disease in the lateral compartment was seen in only 4 cases in our series. In 6 patients failure was associated with recurrent medial medial joint pain with increasing varus deformity. In these cases the mechanism of failure was probably the result of an excessive medial load from a gross undercorrection of the mechanical axis which passed close to or outside the medial aspect of the knee. The crude revision rate for our series with an average follow-up of 6.4 years was 10 per cent. After excluding the early failures, which resulted largely from the potentially avoidable problems the revision rate was 6.7 per cent. CONCLUSIONS: The results from this series suggest that slight undercorrection of varus deformities does not produce any significant differences in the revision rates for unicompartmental replacements when compared to previous reports. Slight undercorrection would appear, nevertheless, to effect the relative importance of the modes of failure seen. Most notably there are fewer failures from disease in the lateral compartment. This potential advantage, however, is somewhat offset by failures from excessive loading of the medial compartment as technical errors at surgery may result in gross undercorrection of the mechanical axis.
We report a prospective case-controlled study which compared the outcome of knee replacement in seriously deformed and slightly deformed knees. There were 51 knees with varus or valgus deformity greater than 20 degrees matched for age, gender, disease, type of prosthesis and time of operation with a control group in which the alignment of the leg was within 5 degrees of normal. The clinical outcome at a mean 5.5 years was similar in the two groups. Some deformity persisted in 14 patients in the first group, 13 of whom were initially in valgus. These patients had a significantly poorer mean clinical outcome. Lateral dislocation or subluxation of the patella was found in four knees, all of which had had valgus deformity of 30 degrees or more.
Three cases of posterior tibial nerve palsy following reamed intramedullary nailing of the tibia are presented. This is a rare complication causing considerable morbidity. The possible mechanisms of neural injury are reviewed and guidelines for prevention are outlined.
We describe the use of intramedullary reconstruction nails in the treatment of 14 patients with pathological subtrochanteric fractures and coexisting metastases in the femoral shaft. After nailing, all patients were free from pain and regained mobility. They were followed up clinically and radiologically until death from the primary disease. There were no mechanical failures even when a less than ideal reduction had been achieved.
We made a prospective study of the incidence and natural history of algodystrophy and associated changes in bone mineral density in the ankles and feet of 60 consecutive patients who had suffered unilateral fractures of the tibial shaft. At bone union, 18 patients showed signs of algodystrophy. Its development was independent of the type of fracture management and of the severity of injury. Patients with algodystrophy lost significantly more bone mineral than did those without but the degree of this loss was independent of the type of treatment and of the time to fracture union. In most cases the symptoms resolved within six months of fracture union but in four patients they were still present at one year and two of these had not returned to work.
We describe 11 cases of posterior fracture-dislocation of the shoulder that required open reduction and fixation. Difficulties with access through anterior approaches led us to use the superior subacromial approach. This is an extension of the approach often used to expose the rotator cuff; the joint is opened by splitting the supraspinatus tendon 5 mm behind the cuff interval. The glenoid, proximal humerus and any fracture fragments can be seen from above, allowing reduction of the dislocation and osteosynthesis to be performed with minimal risk of damage to the humeral head and its blood supply. The proximity of the axillary nerve limits the exposure of the proximal humeral shaft. The superior subacromial approach is ideal for posterior dislocation with fracture of the articular segment, but is not suitable when there is a fracture of the proximal humeral shaft.
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The excision and replacement of a failed aortic valve bioprosthesis in a composite tubular graft in two patients with Marfan syndrome was accomplished without replacing the composite graft.