Introduction:

Unicompartmental knee arthroplasty (UKA) has been used in the past decades to treat progressive cartilage degeneration in a single compartment. Concern has been raised over the rate of revision procedures for polyethylene wear and osteoarthritic progression into the adjacent compartment. Few studies have examined the pathology of cartilage degeneration in the setting of UKA. This study aims to investigate the viability of knee chondrocytes introduced to high and low concentrations of orthopaedic wear debris particulate.

Purpose: Damage to articular cartilage leads to an incomplete healing response. This has elicited interest in improving the understanding of chondrocyte biology and finding ways to stimulate a more effective repair response. Neuropeptides play a role in the proliferative and reparative processes of many tissue types, but little is known about their effects on articular cartilage. This research aimed to investigate the effect of four neuropeptides on articular chondrocytes.

Method: Bovine chondrocytes were cultivated in monolayer culture in media alone or media containing one of four neuropeptides: NPY, CGRP, SP, and VIP. Enzymatically digested chondrocytes from the articular surface of the femoral trochlea, femoral condyles, and patella of freshly slaughtered veal (n=8) were plated at 1×10^5 cells/mL in DMEM complete media with 5% FCS. Proliferation and proteoglycan assays were conducted at days 2,4,6, and 8.

Results: Substance P showed a statistically significant stimulatory effect on chondrocyte proliferation and proteoglycan production that was greatest at a concentration of 5 μg/ml. NPY and VIP showed a dose dependent suppressive effect on chondrocyte proliferation that was greatest at their highest concentrations and was significant at all time points, with the exception of VIP at day 2. CGRP showed no significant effect on proliferation or proteoglycan production.

Conclusion: Substance P showed a reliable stimulation of chondrocyte proliferation and proteoglycan production while NPY and VIP showed dose-dependent depressive effects. These findings support the idea that the peripheral nervous system, through neuropeptides, exerts direct influence on articular chondrocytes. This may provide some insight into the pathophysiology of inflammatory and degenerative arthritis and provide targets for modifying the repair response of articular cartilage.

Purpose: Osteoarthritis (OA) is the most common form of arthritis in the United States and according to the National Institutes of Health, affects over 21 million people. This degenerative joint disease has repeatedly been linked to obesity. It is hypothesized that obesity, defined as a body mass index (BMI) over 30 kg/m2, increases the incidence of OA through increased joint pressure and disruption of normal metabolism. The actual changes in metabolism resulting from obesity and possibly preceding OA have not been thoroughly investigated. The purpose of this study was to identify the relationship between chondrocyte metabolism and BMI in osteoarthritic tissue.

Method: Grade 0 or 1 cartilage was removed from the medial and/or lateral femoral condyles after total knee arthroplasty. Isolated chondrocytes were then resus-pended in alginate beads at 2×106 cells/mL. The beads were equilibrated in media containing 10% fetal bovine serum for 7 days (37°C) and then separated into wells (8 beads/well) with 1 mL media. Media was replaced every 48 hours. At day 5, 9, and 13 days, glycosamino-glycan (GAG) content was measured in the cell pellet, alginate, and saved media using the dimethylmethylene blue (DMMB) assay. The DMMB results were normalized to DNA content. All procedures were approved by the University of Wisconsin – Madison, Institutional Review Board.

Results: At day 5, the average normalized GAGs from the obese group (BMI > 30 kg/m2) was > 4-fold higher than the average normalized GAGs in the non-obese group (BMI < 30 kg/m2). The 4-fold difference in normalized GAGs continued at day 9 with significance (p=0.0087) and widened at day 13, without significance. Some osteoarthritic knees had less tissue quality, therefore GAG testing was limited to earlier study days resulting in variable sample numbers for each study day.

Conclusion: The study results reveal a significant relationship between normalized GAGs and BMI in this population of osteoarthritic patients, supporting the connection between osteoarthritis and obesity previously reported. Higher patient BMI (> 30 kg/m2) may be similar to dynamic compression injuries that cause increased GAG synthesis in response to cartilage damage. In conclusion, elevated normalized GAGs in obese patients’ chondrocytes suggests increased cartilage damage.

Introduction: Spinal deformities (scoliosis, kyphosis or kyphoscoliosis) in children under 10 years of age result from congenital, neuromuscular and idiopathic etiologies. The progression of the deformity is affected by its nature, location and age of onset. Spinal arthrodesis is the procedure of choice in patients with progressive deformities. The use of instrumentation facilitates curve correction and arthrodesis rates. Pediatric spinal surgery is technically demanding, and is still considered controversial. The advent of reduced size spinal instrumentation allowed surgeons to expand their use to pediatric patients. The use of spinal instrumentation in children with various spinal deformities has not been well documented.

Objective: To assess the safety and efficacy of spinal arthrodesis in young patients with progressive spinal deformities.

Patients and Methods: We retrospectively reviewed the medical charts and radiographs of 25 patients younger than 10 years of age who underwent corrective surgery for various spinal deformities. Radiographic outcome, fusion rates and complication were compared between instrumented and non instrumented patients.

Results: At two years of follow up instrumented corrective procedures resulted in superior correction compared to non-instrumented patients and in solid arthrodesis in all. Complications were infrequent.

Conclusions: The use of reduced size spinal instrumentation in young patients with progressive spinal deformities is safe and effective. Curve correction, length of bracing and fusion rates are all in favour of instrumentation, wile complication rates are acceptable. The use of spinal instrumentation in young patients requires expertise and patience.

Purpose: To describe the role of osteotomies in rigid spinal deformities

Patients and Methods: One hundred fifty six patients with spinal deformities undergoing surgery between March 1998 and August 2005 were identified from our spine registry. Our study cohort included 23 cases where osteotomies were performed for correction.

Corrective osteotomies were one of: 1) wedge osteotomy convex based; 2) wedge osteotomy dorsally based; 3) complex wedge or eggshell osteotomy for combined frontal and sagittal plane deformity. Patient’s demographics, type of deformity, underlying conditions, operative results, complications, and need for secondary procedures were documented.

Results: Twenty three patients (15%) with rigid curves underwent osteotomies as part of their corrective surgery. Mean age in this cohort was 11.3 years (2–26), 35% were males, 65% females. In 17 of the patients the main deformity was scoliosis, in 5 – kyphosis and in – 1 lordosis. MMC was the leading underlying condition in 4 cases, followed by VACTER syndrome (2), congenital myopathy (2), arthrogryposis and pterygium (2), Neuro-blastoma (1) and other congenital conditions. Operative results were satisfactory in terms of cosmetics, alignment and function. In 3 cases (13%) complications were encountered, with 2 infections requiring debridement, (one requiring hardware removal) and 1 Neurofibromatosis patient undergoing her 8^th surgical procedure, developing an intraoperative partial neurological injury with nearly full recovery.

Conclusions: Osteotomies are an important part of surgery in rigid spinal deformities. These deformities occur frequently in syndromatic children making peri-operative treatment more complex. Osteotomies facilitate better outcome in terms of correction, sagittal and coronal balance and cosmetics. These procedures are highly demanding technically. However, it is our opinion that adequate correction of rigid deformity with the benefit of spinal column shortening by way of osteotomy, is protective from significant neurological traction injuries that otherwise may occur.

Treatment of congenital kyphosis with severe angular dysplastic spine in children with myelomeningocele (MMC) is one of the most difficult spinal procedures. Most of the surgeons support kyphectomy with long segmental spinal instrumentation and postoperative immobilization by thoracolumbosacral orthosis.

Several spinal deformities are seen frequently in patients who have MMC. The deformity may be congenital or paralytic. Congenital lumbar kyphosis is less common, but most difficult in patients with MMC, occurring in 10–20% of patients. Most curves are congenital and rigid, often more than 80° at birth, and rapidly progresses.

With progression of kyphotic deformity, patients experience recurrent skin breakdown over the apex of the kyphos; impaired sitting balance; the necessity of using their hands for support; collapsing spine and decreasing of lumbar height reduce the capacity of the abdominal cavity and resulting in reduced respiratory capacity and malnutrition. The poor posture and short abdomen make it difficult to manage the patients’ urological needs. A severe deformity raises difficulties in social and psychological development.

Non-operative treatment with spinal orthoses may provide only temporary correction of a kyphotic deformity, but does not prevent progression and skin breakdown.

The goal of surgical treatment is correction of spinal deformity by long segmental instrumentation and achievement of a solid spine fusion in order to allow a balanced sitting position and to prevent complications.

From 1983 to 2001, 6 patients with thoracic level myelomeningocele and severe kyphotic deformity were referred for surgical correction. There were 5 males and 1 female patients with average age at the time of surgery of 8.3 years (range 4.3–13 years). All patients suffered from severe kyphosis, range 90° to 130°, average – 108°. All of them underwent posterior ligation of spinal cord during resection of lordotic segment of the kyphos, and segmental spinal fixation of the deformity from the thoracic spine to the sacrum. In all cases following the resection of the vertebrae it was possible to correct the deformity.

All patients were available for follow-up with range of 6–216 months, average 85 months. All of them were satisfied with the surgical outcome and presented in their final clinical examination with balanced and comfortable sitting, without soft tissue complications. In all cases a significant correction of the deformity was achieved (15°–30°) and enabled comfortable and stable sitting. Two patients suffered post-operative complications, one from surgical wound infection which required surgical debridement followed by soft tissue covering, and the other suffered from distal migration of the rod which was shortened later on.

Discussion: Kyphotic deformity in a patient who has MMC is a challenge for the orthopaedic surgeon and requires major surgical intervention. Resection of the kyphos with posterior instrumentation and fusion may solve patient’s functional problems.

We report four children aged two to nine years with traumatic tears of the transverse ligament of the atlas and atlanto-axial subluxation. This is extremely rare in this age group since trauma usually causes a skeletal rather than a ligamentous injury. The injuries resulted from falls or motor vehicle accidents, with considerable delay in diagnosis. Flexion radiographs showed atlas-dens intervals (ADI) of 6, 7, 8 and 13 mm; all four patients were treated by posterior fusion at C1-C2 after the failure of conservative treatment. In one child with quadriparesis and a fixed ADI of 13 mm, transoral anterior resection of the odontoid was performed before the fusion. Diagnosis of this traumatic lesion requires a high level of suspicion. Conservative treatment is likely to fail; surgical stabilisation is indicated.

We report two cases of Serratia marcescens infection at the sites of spinal fractures and emphasise the fact that neurological deterioration soon after spinal fracture may be due to acute vertebral osteomyelitis.