Failure of a Medial Unicompartmental Knee Replacement due to Metal Allergy.

Metal hypersensitivity is an uncommon complication of knee arthroplasty that can lead to significant functional impairment and aseptic prosthesis failure. We describe the case of a 65-yr-old female patient who presented with persistent pain, swelling, and instability 1 yr after medial unicompartmental knee arthroplasty (UKA). The patient had no history of trauma or fall. The initial clinical examination showed good range of movement in the knee joint and no signs of infection or inflammation. Initial radiographs did not reveal aseptic loosening of the implant. Inflammatory markers were normal and the patient was sent for a bone scintigraphy that revealed increased uptake of the femoral implant. Pain deteriorated during the proceeding weeks, and repeated radiographs revealed loosening and dislocation of the femoral implant. We performed a nickel lymphocyte proliferation skin allergy test that resulted in a positive reaction. Revision total knee arthroplasty was performed using an oxynium (zirconium metal alloy) implant with intraoperative tissue pathology and postoperative leukocyte transformation testing that confirmed metal hypersensitivity as the cause for aseptic implant failure. This case report demonstrates that clinical and laboratory signs suggesting metal hypersensitivity in knee arthroplasty can suggest early loosening and failure of the implant.

Effects of fat pad excision on length of the patellar tendon after total knee replacement.

PURPOSE: We report our results of the effect that total fat pad excision has on patellar tendon length following total knee replacement. METHOD: We retrospectively reviewed radiographs of the knees of 133 patients who had Depuy LCS uncemented TKR between January 2009 to December 2009. We excluded patients who had patella resurfacing, lateral release, knee replacement for other than osteoarthritis and who had other implants used. We measured the length of the patellar tendon using the Insall-Salvati ratio.(.) Changes in the length of the tendon were calculated both as an absolute evaluation and as a percentage of the original length. RESULTS: We effect of fat pad excision on patellar tendon length at 1 year and 5 years following surgery. At one year we observed no change in patellar tendon length in 81.1%, patella infera in 17.3% and patella alta in 1.6% of these 133 patients. We manage to follow up 50 of these patients at 5 years following surgery. In comparison to pre-operative length, at one year 86% showed no change, 14% had patella infera and none had patella alta. At 5 years we observed no change in 98% and patella infera in 2% of patients. Forty nine percent of our patients with patella infera developed anterior knee pain, mean flexion in those patients was 95.625° and mean oxford score was 52.31. CONCLUSIONS: In our patients following single implant design used patella infera developed in up to 18% at one year following surgery. Two percent of fifty patients who had five years follow up showed further shortening of patellar tendon after one year. We conclude that complete fat pad excision during total knee replacement does affect patellar tendon length. Level of evidence IV.

Correction of simple and complex pediatric deformities using the Taylor-Spatial Frame.

INTRODUCTION: Correcting multiplanar lower-limb pediatric deformities requires complex and, in many cases, staged procedures. The Taylor-Spatial Frame (TSF) is a sophisticated external fixator system that can be used to treat simple to complex multiplanar and multiapical skeletal deformities. We describe its use in 53 children during the last 7 years in a variety of pathologies and demonstrate its ease of use and versatility. METHODS: A review of medical and physiotherapy records, radiographs, and computed tomographic scans of all patients treated with a TSF between June 1999 and December 2005 at the Booth Hall Children's Hospital was conducted. Data recorded were etiology of deformity, sex, age, number of previous operations, preoperative deformity parameters, operative records and frame constructs, treatment regime, frame duration, follow-up protocol, posttreatment deformity, complications, and clinical and radiological outcome. RESULTS: Fifty-three patients between the ages of 12 months and 16 years (mean, 10.7 years) underwent correction programs for 55 limbs (44 tibia and 11 femurs). The etiology of deformity was congenital in 39 cases and acquired in 14. We were able to achieve an acceptable correction of deformity (leg length discrepancy <15 mm, angulation <5 degrees) in 52 limbs. A number of complications were encountered, which are discussed. DISCUSSION AND CONCLUSION: We demonstrate its ease of use for both surgeon and patient and its versatility in a variety of pathologies. The advantages of the TSF system are many. It is a simple frame construct, and application is easy. The plan and execution are structured with precise end points; it is a single-stage correction and thus avoids frame modifications. Any residual deformity can be further corrected by use of the same frame. We conclude that the TSF is an effective and efficient way to correct a wide variety of simple and complex often obstinate pediatric limb deformities.

Avascular necrosis of the intermediate cuneiform bone.

We present a case of avascular necrosis of the intermediate cuneiform bone in a skeletal immature patient with a spontaneous recovery following conservative treatment. We discuss the aetiology and options of treatment.

The behaviour of the periosteum during callotasis.

Periosteal behaviour during callotasis has been studied in animals but not in humans. Markers were inserted into the periosteum of seven patients who underwent callotasis. All of them had tibial callotasis, five patients had bone transport procedure and two had leg lengthening due to congenital disorder. They were followed up radiologically at regular intervals and during the distraction the movement of the periosteal markers was recorded. This enabled observation of the way the periosteum elongates during the procedure and also the calculation of periosteal strain at different stages at the points where the periosteum is fixed to bone. The study indicated that in most cases the periosteum acts as an elastic sleeve surrounding the newly formed tissue during lengthening. The site of attachment between sleeve and cortex became established early during lengthening, and hardly changed position at later stages. There was a wide spread of attachment sites and periosteal strains. Attachment sites were not related to pin or wire entry points, and strains were not predictive of callus shape or healing time.