ABSTRACT
BACKGROUND: Today, biological fixation of uncemented press-fit acetabular components plays an important role in total hip arthroplasty. Long-term stable fixation of these implants depends on the osseointegration of the acetabular cup bone tissue into the acetabular cup implant, and their ability to withstand functional loads. AIM: To compare the strength of bone-implant osseointegration of four types of porous metal implants in normal and osteoporotic bone in rabbits. METHODS: The study was performed in 50 female California rabbits divided into non-ovariectomized (non-OVX) and ovariectomized groups (OVX) at 6 mo of age. Rabbits were sacrificed 8 wk after the implantation of four biomaterials [TTM, CONCELOC, Zimmer Biomet's Trabecular Metal (TANTALUM), and ATLANT] in a 5-mm diameter defect created in the left femur. A biomechanical evaluation of the femur was carried out by testing implant breakout force. The force was gradually increased until complete detachment of the implant from the bone occurred. RESULTS: The breakout force needed for implant detachment was significantly higher in the non-OVX group, compared with the OVX group for all implants (TANTALUM, 194.7 ± 6.1 N vs 181.3 ± 2.8 N; P = 0.005; CONCELOC, 190.8 ± 3.6 N vs 180.9 ± 6.6 N; P = 0.019; TTM, 186.3 ± 1.8 N vs 172.0 N ± 11.0 N; P = 0.043; and ATLANT, 104.9 ± 7.0 N vs 78.9 N ± 4.5 N; P = 0.001). In the OVX group, The breakout forces in TANTALUM, TTM, and CONCELOC did not differ significantly (P = 0.066). The breakout force for ATLANT in the OVX group was lower by a factor of 2.3 compared with TANTALUM and CONCELOC, and by 2.2 compared with TTM (P = 0.001). In the non-OVX group, the breakout force for ATLANT was significantly different from all other implants, with a reduction in fixation strength by a factor of 1.9 (P = 0.001). CONCLUSION: TANTALUM, TTM, and CONCELOC had equal bone-implant osseointegration in healthy and in osteoporotic bone. ATLANT had significantly decreased osseointegration (P = 0.001) in healthy and in osteoporotic bone.
ABSTRACT
Sagittal band injuries may result in extensor digitorum communis (EDC) tendon instability and may require operative treatment for symptomatic loss of extension, pain, and snapping at the metacarpophalangeal joint (MCPJ). Operative methods vary according to the source of donor tissue, as well as the anchor point of attachment. We present a surgical technique that diminishes tension of the repair with MCPJ flexion. Twenty-two EDC tendon stabilization procedures were performed between 2006 and 2017 using a tendon flap method. The selection criteria for this group of patients included completely dislocating extensor tendons with persistent complaints of pain and decrease in finger extension despite at least a 6-week conservative treatment attempt. All subjects underwent surgical treatment for tendon centralization using a distally based tendinous flap from the EDC sutured to the adjacent finger volar plate. A mathematical model was developed to analyze repair tension at 30, 60, and 90 degrees of MCPJ flexion calculating the flap length difference of 2 attachment points: deep transverse metacarpal ligament versus adjacent volar plate. Centralization was maintained in all digits with no evidence of subluxation at final postoperative evaluation. Clinical symptoms of pain and weakness resolved in all patients. Mathematical modeling provided evidence that translation of the anchor point of reconstructed flap to the volar plate of the adjacent finger resulted in lower tensile forces when compared with attachment at the intermetacarpal ligament. This optimized forces on reconstructed tendon flap experienced during MCPJ flexion.Level of Evidence: Level IV-therapeutic, case series.
