Cortical hypertrophy with a short, curved uncemented hip stem does not have any clinical impact during early follow-up.

BACKGROUND: Short stems have become more and more popular for cementless total hip arthroplasty in the past few years. While conventional, uncemented straight stems for primary total hip arthroplasty (THA) have shown high survival rates in the long term, it is not known whether uncemented short stems represent a reasonable alternative. As cortical hypertrophy has been reported for short stems, the aim of this study was to determine the radiographic prevalence of cortical hypertrophy and to assess the clinical outcome of a frequently used short, curved hip stem. METHODS: We retrospectively studied the clinical and radiographic results of our first 100 consecutive THAs (97 patients) using the Fitmore® hip stem. Mean age at the time of index arthroplasty was 59 years (range, 19 - 79 years). Clinical outcome and radiographic results were assessed with a minimum follow-up of 2 years, and Kaplan-Meier survivorship analysis was used to estimate survival for different endpoints. RESULTS: After a mean follow-up of 3.3 years (range, 2.0 - 4.4 years), two patients (two hips) had died, and three patients (four hips) were lost to follow-up. Kaplan-Meier analysis estimated a survival rate of 100 % at 3.8 years, with revision for any reason as the endpoint. No femoral component showed radiographic signs of loosening. No osteolysis was detected. Cortical hypertrophy was found in 50 hips (63 %), predominantly in Gruen zone 3 and 5. In the cortical hypertrophy group, two patients (two hips; 4 %) reported some thigh pain in combination with pain over the greater trochanter region during physical exercise (UCLA Score 6 and 7). There was no significant difference concerning the clinical outcome between the cortical hypertrophy and no cortical hypertrophy group. CONCLUSIONS: The survival rate and both clinical and the radiographic outcome confirm the encouraging results for short, curved uncemented stems. Postoperative radiographs frequently displayed cortical hypertrophy but it had no significant effect on the clinical outcome in the early follow-up. Further clinical and radiographic follow-up is necessary to detect possible adverse, long-term, clinical effects of cortical hypertrophy.

Long-term durability of alumina ceramic heads in THA.

BACKGROUND: The optimal type of bearing for hip arthroplasty remains a matter of debate. Ceramic-on-polyethylene (CoP) bearings are frequently used in younger and more active patients to reduce wear and increase biocompatibility compared to Metal-on-Polyethylene (MoP) bearings. However, in comparison to metal heads, the fracture risk of ceramic heads is higher. In addition, ceramic head fractures pose a serious complication which often necessitates major revision surgery. To date, there are no long-term data (>20 years of follow-up) reporting fracture rates of the ceramic femoral heads in CoP bearings. The purpose of this research was to investigate long-term CoP fracture rate. METHODS: We evaluated the clinical and radiographic results of 348 cementless THAs treated with 2nd generation Biolox Al2O3 Ceramic-on-Polyethylene (CoP) bearings consecutively implanted between January 1985 and December 1989. The mean age at implantation was 57 years. The patients were followed for a minimum of 20 years. At the final 111 had died, and 5 were lost to follow-up. The cumulative incidence of ceramic head fractures in the long-term was estimated using a competing risk analysis. RESULTS: The cumulative incidence of ceramic head fracture after 22-years was estimated with a competing risk analysis at 0.29% after 22-years (SE = 2.09%; 95% - CI: 0.03-1.5%). The radiographic analysis revealed no impending failures at final follow-up. DISCUSSION/CONCLUSION: The fracture rate of second-generation ceramic heads using a CoP articulation remains very low into the third decade after cementless THA.

Complete subchondral bone defect regeneration with a tricalcium phosphate collagen implant and osteoinductive growth factors: a randomized controlled study in Göttingen minipigs.

The restoration and reconstruction of osseous defects close to the joint, constitutes a challenging field for reconstructive surgery. A dual-layer implant of ß-tricalcium phosphate (TCP) and a collagens I/III scaffold was evaluated in a prospective, randomized comparison in a larger animal model. For this purpose, a standardized osteochondral defect was created in the medial facet of the patellar groove in both stifle joints of Göttingen minipigs. Critical-size osseous defects were either left empty (spontaneous healing; group 1; n = 12) or treated with the two-layer TCP collagen implant (group 2; n = 12). In group 3 (n = 12), additional growth factor mixture (GFM) was supplemented (bone morphogenetic proteins 2, 3, 4, 6, 7, and TGF-ß1, 2, 3). Osseous defect regeneration was assessed at 6, 12, and 52 weeks postoperatively (n = 4). Qualitative and quantitative histomorphometric assessment of defect regeneration and bone substitute resorption was conducted by means of light microscopy, fluorescence microscopy, and microradiography. Critical-size defects did not heal spontaneously throughout follow-up (group 1: max. 21.84 ± 2.81% defect area at 52 weeks). The TCP layer of the implant significantly increased the amount of new bone formation with 29.8 ± 9.68% at 6 weeks and 40.09 ± 4.76% at 12 weeks when compared with controls. After 52 weeks, the TCP was almost fully degraded (4.35 ± 3.70%) and the defect was restored with lamellar trabecular bone (31.28 ± 5.02%). Growth factor supplementation resulted in earlier resorption of the TCP implant and faster defect regeneration. The dual-layer TCP collagen implant is suitable to restore subchondral osseous defects. Additional use of GFM increased the resorption of the TCP layer, but did not foster new bone formation.

High survival in young patients using a second generation uncemented total hip replacement.

PURPOSE: Whilst excellent long-term results with contemporary uncemented stems have been reported for total hip arthroplasty in young patients, the survival rates for the whole reconstruction are often compromised by high failure rates on the acetabular site due to peri-acetabular osteolysis and accelerated wear. METHODS: In patients 60 years old or younger, we retrospectively reviewed the results at a minimum of ten years of 89 consecutive uncemented total hip replacements in 88 patients using the press-fit Fitmore acetabular component in combination with the CLS Spotorno stem and a 28-mm Metasul metal-on-metal articulation or a 28-mm alumina ceramic on conventional polyethylene bearing. The mean age at the time of surgery was 49 years (range, 25-60). The mean clinical and radiological follow-up was 12 years (range, 10-15). RESULTS: Six patients (six hips) died and two patients (two hips) were lost to follow-up. Five hips were revised: one for deep infection, one for peri-prosthetic femoral fracture, and one for aseptic stem loosening. In two hips an isolated revision of the acetabular liner was performed (one for recurrent dislocation and one for unexplained pain). No revision was performed for accelerated wear, osteolysis or aseptic loosening of the acetabular shell. We could not detect peri-acetabular osteolysis visible on plain radiographs in those hips evaluated radiographically. The Kaplan-Meier survival with revision for any reason as the endpoint was 94% (95% confidence interval, 86-97) at 12 years. CONCLUSIONS: The survival rates and the radiological outcomes with this implant combination in this young and active patient group are encouraging when compared to the results reported for other uncemented cups in this age group.