Aims

Osteosarcoma is the most common primary bone malignancy among children and adolescents. We investigated whether benzamil, an amiloride analogue and sodium-calcium exchange blocker, may exhibit therapeutic potential for osteosarcoma in vitro.

Nerve damage is a complication of THA and TKA procedures. The incidence of subclinical nerve injury following arthroplasty is unknown. The aim was to determine the prevalence of asymptomatic nerve deficits in an arthroplasty population group, and the incidence of post-operative changes in nerve function. A Secondary aim was to identify the nature of any deficits. And the association between nerve deficits and history of backache.

A non-randomised prospective series of patients undergoing lower limb arthroplasty for osteoarthritis were studied at a single hospital. The peroneal nerve was investigated using nerve conduction in forty patients. Twenty patients had upper limb testing to differentiate between a polyneuropathy or isolated lower limb neuropathy.

Nerve function deficits were detected in the peroneal nerve in fifteen patients pre-operatively and fifteen post-operatively, of those twelve had A waves detected suggestive of a generalised neuropathy. Ten patients who had upper limb testing had a conduction defect (five had asymptomatic Carpal tunnel). There was a positive correlation between presence of post-operative deficit and age(r=0.389, p=0.013). A negative correlation was found for presence of post-operative A waves and BMI(r=−0.370, p=0.019).

The prevalence of pre-operative subclinical peroneal neuropathy is much higher than expected in this group (37.5%) of arthroplasty patients. There is a strong correlation between presence of post-operative conduction abnormalities and age. There is no relationship between peripheral neuropathy and history of backache or residual post-operative deficit.

Components from 73 failed knee replacements (TKRs) consisting of rotating-platform, mobile-bearing and fixed-bearing implants were examined to assess the patterns of wear. The patterns were divided into low-grade (burnishing, abrasion and cold flow) and high-grade (scratching, pitting/metal embedding and delamination) to assess the severity of the wear of polyethylene.

The rotating-platform group had a higher incidence of low-grade wear on the upper surface compared with the fixed-bearing group. By contrast, high-grade wear comprising scratching, pitting and third-body embedding was seen on the lower surface. Linear regression analysis showed a significant correlation of the wear scores between the upper and lower surfaces of the tibial insert (R² = 0.29, p = 0.04) for the rotating-platform group, but no significant correlation was found for the fixed-bearing counterpart.

This suggests that high-grade wear patterns on the upper surface are reduced with the rotating-platform design. However, the incidence of burnishing, pitting/third-body embedding and scratching wear patterns on the lower surface was higher compared with that in the fixed-bearing knee.

The size selection of the outer metal shell to fit the acetabulum is a dilemma to the surgeons for the bipolar hemiarthroplasty. However, no body ever mentioned the final results of motion behaviour of bipolar hip endoprostheses by different size selections of outer metal shell. The purpose of this study was to evaluate the motion behaviour of bipolar hip endoprostheses under different sizes of outer metal shell.

A fresh cadaver of size of 50 mm and three different sizes of bipolar hip endoprostheses were used to evaluate the motion behaviour of bipolar hip endoprostheses under the MTS machine. Each size had six sets of bipolar hip endoprostheses to get statistical data. The single axial load scaled from 300 N to 3000 N with increment of 300 N was applied on both the inner bearing and outer bearing to obtain the frictional torque of two bearings randomly. The axis was rotated from 0° to 90° under the speed of 1 deg/sec. The motion behaviour of bipolar hip endoprostheses was predicted and verified by the comparison of the frictional torque of both bearings and repeat the experiments again.

The dynamic frictional torque of 48mm was larger than the dynamic frictional torque of the 50mm at the inner bearing. The size of 52mm had the largest value of dynamic frictional torque for the outer bearing under any load condition. The prosthesis that had larger outer metal shell than the acetabulum had the same relative motion behaviour as the design hypotheses, because the difference of frictional torque was much higher.

In conclusion, the motion of the bipolar hip endoprostheses is influenced by the frictional behaviour of the both bearings. The relative motion of bipolar hip endoprostheses with a larger outer shell size will have an idea relative motion behaviour, because the larger difference of frictional torque. The thickness of the UHMWPE has a positive effect to reduce the friction between the UHMWPE liner and metal head.

Background Data: Postoperative spondylothesis had been noted for many years, first reported by White in 1977. Biomechanic effect of the facetectomy was reported by Abumi in 1992. There were few reports about the results of surgical treatment for postoperative spondylolisthesis.

Purpose: To assess the outcome of surgical treatment for postoperastive spondylolisthesis and examine the factors that might correlate with postoperative spondylolisthesis.

Materials and Methods: This study retrospectively reviewed twenty seven patients (eleven male and sixteen female), from 1979 to 1996, who received pedicle screws instrumentation and posterolateral fusion for postoperative spondylolisthesis. Average age was 57.3 years old (from 36.6 to 79.5 years old). Average follow-up time was 40.0 months (from 24 months to 72 months). The grade of fcetectomy, percentage of vertebral slipping, and disc narrowing was checked by plain X-ray. End results were assessed using the modified Stauffer-Coventry’s evaluation criteria.

Results: The mean period of postoperative instability was 49.3 months (from 6 months to 141 months) in whole group, 43.7 months (from 6 months to 129 months) in laminectomy group, 43.4 months (from 17months to 82 months) in laminectomy and disectomy groups, and 74.6 months (13 months to 141 months) in disectomy group. After an average follow-up period of 40 months, 29.6 % of patients had excellent results, 44.5% had good results, and 25.9 % had fair result. No complication was found in this study.

Conclusions: Pedicle screw instrumentation with posterolateral fusion can get satisfactory result for postoperative spondylolisthesis.

Of 37 consecutive patients suffering from tuberculosis of the lumbosacral spine, 26 were reviewed after an average follow-up of 20 years. Those presenting at under 10 years of age usually had a discharging sinus or a pointing abscess and a visible kyphosis. In older patients, low back pain was the predominant presenting symptom. Neurological involvement was uncommon. Both operative and conservative treatment had resulted in fusion but all patients treated conservatively ended up with a kyphosis associated with trunk shortening. They had a higher incidence of back pain and more complications in pregnancy. Anterior debridement and fusion with a strut graft can reduce the incidence and size of kyphosis, but is technically demanding. Treatment remains difficult and requires individual consideration.

We reviewed 20 adult patients with spondylolysis and isthmic spondylolisthesis an average of 10.5 years after treatment by anterior spinal fusion. Nineteen patients had excellent or satisfactory results. Ten of the patients were symptom-free at one year, and 15 were asymptomatic at final follow-up. Anterior spinal fusion can produce results comparable to those of posterior fusion with or without decompression. The results tend to improve with time in contrast to the known worsening of late results after posterior decompression without fusion.

Twenty-two patients with late onset Pott's paraplegia presenting at a mean of 18 years after initial symptoms were reviewed an average of seven years after treatment by anterior decompression and fusion. Fourteen patients had active disease, and in 12 of these, activity at the internal kyphus was the direct cause of the paraplegia. In the other two, a soft healing bony ridge was the cause. The eight patients with healed disease had hard bony ridges compressing the cord. The response to anterior decompression was faster, better and safer in patients with active disease: nine recovered completely and three significantly. In patients with healed disease, the anterior decompression was technically more difficult and the recovery less satisfactory. Significant complications included two cases with neurological deterioration, two with cerebrospinal fluid fistulae and four with neurapraxia of the cord.

We reviewed 40 cementless Porous Coated Anatomic knee replacements in 34 consecutive patients. The average follow-up was 12.9 months (range 6 to 36 months). At review, loose beads were identified in 23 knees, in 11 on the femoral side and in 16 on the tibial side (in five knees on both sides). One loose bead was adjacent to the patella. In four knees there were intra-articular beads. Radiolucent lines at the interface between bone and prosthesis were seen in 19 knees, in six on the femoral side and in 16 on the tibial side (in three knees on both sides). In relation to the tibial component loose beads were associated with a radiolucent line in all except one case. Progressive loosening with an increasing number of loose beads was seen in three knees. At this early stage of follow-up there was no correlation between the clinical results and the presence of loose beads.