Our aim was to evaluate the radiographic characteristics of patients
undergoing total hip arthroplasty (THA) for the potential of posterior
bony impingement using CT simulations. Virtual CT data from 112 patients who underwent THA were analysed.
There were 40 men and 72 women. Their mean age was 59.1 years (41
to 76). Associations between radiographic characteristics and posterior
bony impingement and the range of external rotation of the hip were
evaluated. In addition, we investigated the effects of pelvic tilt
and the neck/shaft angle and femoral offset on posterior bony impingement.Aims
Patients and Methods
Total ankle replacement (TAR) is increasingly used in the treatment of end-stage ankle arthropathy, but much debate exists about the clinical result. The goals of present study are: 1) to provide an overview of the clinical outcome of 58 TAR's in a single centre and 2) to assess the association between radiological characteristics and clinical outcome. We reviewed a prospective included cohort of 58 TAR's in 54 patients with a mean age of 66.9 (range 54–82) and a mean follow-up of 21.6 months (range 1.45–66.0). The TAR's where performed by a single surgeon in a single centre (MUMC) between 2010 and 2015, using the CCI ankle replacement. A standard surgical protocol and standardized post-op rehabilitation was used. Patients were followed-up pre-op and at 1 day, 6 weeks, 3–6–12 months and yearly thereafter post-op. The AOFAS and range of motion (ROM) were assessed and all complications, re-operations and the presence of pain were recorded. Radiographic assessment consisted of the estimation of prosthesis alignment, migration, translation and radiolucent lines using the Rippstein protocol (1). The clinical outcome was compared with a systematic review of TAR outcome. Ten intra-operative complications occurred and 9 were malleolar fractures. Post-operative complications occurred in 20 out of the 54 patients (37.0%). Impingement (5/54 patients), deep infection (4/54 patients), delayed wound healing (3/54 patients) and minor nerve injuries (3/54 patients) were the most frequently recorded. 18 patients (31.0%) underwent one or more re-operations and 12 of these 18 patients underwent a component revision (mostly the PE insert) or a conversion to arthrodesis. Despite the complications and revisions, the functional outcome improved. Radiologically 15.8% of the TAR's were positioned in varus and 1.8% in valgus. Migration in the frontal and sagittal plane is seen in 3 and 2 TAR's respectively. Radiolucency is significantly increasing with the follow-up time (p=0.009). Migration in the frontal plane is significantly associated with conversion to arthrodesis (p=0.005) and migration in the sagittal plane to revision of a component or conversion to arthrodesis (p=0.04). Finally, pain is significantly associated with re-operations (p=0.023) and complications (p=0.026). Remarkable is that the clinical outcome is independent of the direct post-op alignment of the TAR. The complication-, re-operation and revision or conversion to arthrodesis rates makes the clinical outcome of TAR still questionable favourable. Especially the complication and re-operation incidences are greater than found in the systematic review. However, it is remarkable that the minor complications and re-operations not related to the TAR are not often mentioned in the literature.
Osteolysis and periprosthetic bone loss have been a concern since Charnley’s original reports of metal on Teflon. Willart and Semlitch were the first investigators to propose a biologic mechanism for osteolysis associated with particulate wear debris. Harris in 1976 and Goldring 1983 describe the presence of macrophages and giant cells in the synovial membrane at the bone cement interface in loose THR. Initially it was associated with cement and it was called cement disease. Reports of resorption around cementless implants led to the realization that PE alone was good enough to create bone loss. Aetiology: Submicron wear particles are phagocytosed by macrophages resulting in release of various cellular mediators from these activated cells. Cellular mediators playing significant role in osteolysis are IL-1, IL-6, TNF-a, PGE2. These mediators lead to stimulation and differentiation of osteoclasts and inhibition of osteoblasts. These factors together assist in the dissolution of bone at the interface allowing for micromotion of the prosthesis that leads to further generation of wear debris. On top of the above there is release of collagenase, stromelysin, gelatinase which further destroy the bone. Another active area of research involves roles at Rank, Rank and osteoprotegerin. Recently there is extensive work done as far as it concerns the role of endotoxin in osteolysis and periprosthetic bone loss. It still remains a controversial issue. Other researchers have studied the effects of elevated periarticular hydrostatic pressure and fluid access in the development of osteolysis (effective joint space). Particles bioreactivity: It has been shown that the major determinants of particle bioreactivity are particle size, composition, shape, and concentration. Particles of submicron size are more stimulatory and there is a dose dependent response. Concerning the composition it has been found that UHMWPE, CoCr and stainless steel particles induce more severe reactions than Titanium and alumina ceramic. It also has been found that Al2O3 particles were more easily phagocytosed than UHMWPE at the same size and concentration but TNF-a release was higher with than UHMWPE with Al2O3. Concerning the metal to metal particles it has been found that the volumetric wear is less than M/P with smaller particles and less intensive tissue reaction but Shanbhag reported that bioreactivity of metal wear debris is a function of the total surface area and not the volume of wear debris and casts doubts at the theory that metal to metal wear particles produce a less intense biological response. Concerning the highly crosslinked PE it has been found that wear debris from gamma crossed –linked remelted PE contains very few fibrils after a dose of 5 Mrads and virtually none after 9.5 Mrads. Clinical Manifestations: The majority of patients with osteolysis are asymptomatic. Pain is caused mainly from a fracture.Ultimately periprosthetic bone loss results in aseptic loosening. Furthermore if the component becomes loose bone loss often progress more rapidly resulting in large bone defects that can lead to catastrophic failure or fracture.
