This animal study compares different methods
of performing an osteotomy, including using an Erbium-doped Yttrium
Aluminum Garnet laser, histologically, radiologically and biomechanically.
A total of 24 New Zealand rabbits were divided into four groups
(Group I: multihole-drilling; Group II: Gigli saw; Group III: electrical
saw blade and Group IV: laser). A proximal transverse diaphyseal
osteotomy was performed on the right tibias of the rabbits after the
application of a circular external fixator. The rabbits were killed
six weeks after the procedure, the operated tibias were resected
and radiographs taken. The specimens were tested biomechanically using three-point bending
forces, and four tibias from each group were examined histologically.
Outcome parameters were the biomechanical stability of the tibias
as assessed by the failure to load and radiographic and histological
examination of the osteotomy site. The osteotomies healed in all specimens both radiographically
and histologically. The differences in the mean radiographic (p
= 0.568) and histological (p = 0.71) scores, and in the mean failure
loads (p = 0.180) were not statistically significant between the
groups. Different methods of performing an osteotomy give similar quality
of union. The laser osteotomy, which is not widely used in orthopaedics
is an alternative to the current methods. Cite this article:
Narrow, well-defined radiolucent lines commonly observed at the bone-implant interface of unicompartmental knee replacement tibial components have been referred to as physiological radiolucencies. These should be distinguished from pathological radiolucencies, which are poorly defined, wide and progressive, and associated with loosening and infection. We studied the incidence and clinical significance of tibial radiolucent lines in 161 Oxford unicondylar knee replacements five years after surgery. All the radiographs were aligned with fluoroscopic control to obtain views parallel to the tibial tray to reveal the tibial bone-implant interface. We found that 49 knees (30%) had complete, 52 (32%) had partial and 60 (37%) had no radiolucent lines. There was no relationship between the incidence of radiolucent lines and patient factors such as gender, body mass index and activity, or operative factors including the status of the anterior cruciate ligament and residual varus deformity. Nor was any statistical relationship established between the presence of radiolucent lines and clinical outcome, particularly pain, assessed by the Oxford Knee score and the American Knee Society score. We conclude that radiolucent lines are common after Oxford unicompartmental knee replacement but that their aetiology remains unclear. Radiolucent lines were not a source of adverse symptoms or pain. Therefore, when attempting to identify a source of postoperative pain after Oxford unicompartmental knee replacement the presence of a physiological radiolucency should be ignored.
