Purpose

Various approaches have been reported for the total hip replacement (THR). In recent years, a muscle sparing approach with low postoperative muscle weakness and low dislocation risk has been frequently selected. However, such surgery has a learning curve. Thus, at the time of switching from the conventional approach to such approaches, invasion or infection risk may increase with the operation time extension. The purpose of this study is to clarify the change of invasiveness or latent infection rate with the change in approach in order to select the cases safely at the beginning of introducing a new approach in THR.

The superior analgesic effects of minodronate compared with other bisphosphonates has been previously reported. However, to our knowledge, there are no studies analyzing the analgesic effects of bisphosphonates on chronic pain. The purpose of the present study was to evaluate the analgesic effects of minodronate (MIN), alendronate (ALN), and pregabalin (PRG) on chronic pain caused by chronic constriction injury (CCI) of the sciatic nerve.

Four-week-old female Wister rats underwent ovariectomy. At 8 weeks old, the left sciatic nerve was ligated to induce the chronic pain model (CCI side), and sham surgery was performed on the right posterior limb as a CCI control (control side). The rats were divided into the following four groups: 1) MIN group, administered with minodronate (0.15 mg/kg/week) (n = 10); 2) ALN group, administered with alendronate (0.15 mg/kg/week) (n = 10); 3) PRG group, administered with pregabalin (10 mg/kg) (n = 9); and 4) Control group, administered with vehicle (n = 10). Treatments were administered subcutaneously every week for 2 weeks immediately after CCI. To quantify the sensitivity to a tactile stimulus, paw withdrawal in response to a tactile stimulus was measured using von Frey filaments at 0, 1, and 2 weeks after CCI. Von Frey filaments were applied to the plantar surface of the hindpaws for 3 s, and this was repeated three times. Paw withdrawal in response to the stimulus was evaluated by scoring as follows: 0, no response; 1, a slow and/ or slight response to the stimulus; 2, a quick withdrawal response; 3, an intense withdrawal response away from the stimulus. The mean value of the score was adopted as the pain score. After evaluating the response, bilateral femurs were harvested for bone mineral density (BMD) measurements.

The pain score of the CCI side was significantly higher than that of the sham side in all groups (p < 0.05) at each time point. The pain score for the MIN group, but not the ALN group, of the CCI side was significantly lower (p = 0.05) at 0 and 1 week after CCI. Total femoral BMD of the CCI side was significantly lower in the PRG and Control groups than those of the MIN and ALN groups (p < 0.05). No significant difference was identified for BMD between the MIN and ALN groups.

Minodronate showed a significant analgesic effect on chronic pain and suppressed osteoporotic changes caused by CCI.

We studied 23 patients with spondylolysis of the fifth lumbar vertebra (L5) and 20 with spondylolytic spondylolisthesis at this level. All were more than 40 years of age. The transverse processes at L5 were significantly wider in the former group than in the latter. We also dissected 56 cadavers to study the morphological relationship between the transverse process of L5 and the iliolumbar ligament, and found that the wider transverse process is associated with increased width of the posterior band of the iliolumbar ligament.

If a patient with pars defects has wide transverse processes at L5, the lumbosacral junction may be stabilised by wide posterior bands of the iliolumbar ligament and the fifth lumbar vertebra by the ligament, preventing anterior displacement.