Introduction: Fractures in long bones are frequently managed with intramedullary implants, plates ore external fixators. X-ray images are normally used to determine the point of full weight bearing and implant removal. Plain radiographs give only poor information about the mechanical properties of the healing callus. Several quantitative Methods: like QCT and DEXA provide information about the density of the new bone, but the mechanical properties remain unknown. For direct monitoring of the mechanical properties of the healing callus a 4-point-stiffness device for small animals was constructed. This devise is used to detect the influence of degradable implants on bone healing. Long term aim is to develop “smart” implants that degrade during healing and speed up the healing process.

Materials and Methods: An uniplanar, bilateral external fixator was mounted on the tibiae of New Zealand White Rabbits after osteotomy and introduction of different degradable, intramedullar implants. The 4-point-bending measurement unit was temporarily fixed to record deflection with a non-contact displacement transducer. Load cells were instrumented to record the stepwise load increase (25g). The max. bending moment was only 0.14 Nm to avoid bending of the implant. Additional μ-CT analysis was conducted on the stiffness measurement days to quantify bone healing. After the in-vivo tests the stiffness measurement device was validated with ex-vivo measurements of bone models in a Material Test System (MTS).

Results: The bending stiffness unit showed a high precision with a standard deviation of 5.55E-04 N/μm and a mean deviation error of all models of 1.74E-04 N/μm. We found a significant non-linear correlation between the measured stiffness and the diameter of the models (p< 0.05, r2=0.96). Furthermore a significant correlation between the stiffness device and the MTS in vitro was shown (r2=0.96, p< 0.005). A significant correlation between the data of the bending stiffness device and the MTS was found for all animals (r2=0.64, p< 0.01). μ-CT analysis showed an increase in callus formation and density during the increase in bending stiffness.

Discussion: In this study a precise measurement unit to mirror the mechanical properties of healing bone is presented. The device was successfully tested in an in-vivo model of fracture healing. The healing of callus around different degradable implants can be monitored to develop implants that degrade during fracture healing to avoid stress shielding or implant removal. Not only data about the healing bone can be gatherd with the μ-CT analysis, but also processes around the implants can be well monitored to evaluate degradation and quality of the implants.

Introduction: High developmental hip dislocation is the most severe anatomic constitution type in developmental dysplasia of the hip (DDH). After the age of 30–40 years the pseudo-articulation often becomes painful and requires advanced treatments. To restore limb length dislocation must be reduced by soft tissue release. If the reduction overreaches 40 mm the risk for nerve-damage increases dramatically. Reducing the dislocation, one-step soft tissue releases and slow release by continuous iliofemoral distraction were invented. In this study we report a combination of a one-step soft tissue release and slow continuous iliofemoral distraction in patients requiring over 40 mm distraction for uncemented THA.

Material and Methods: Between 1998 and 2007 20 procedures in 19 patients with an age of 42.5 years (18–69 years) and a leg-length discrepancy of > 4 cm were performed. For 5.6 years (1–12 years) patients were followed-up clinically and radiographically. The treatment consisted of a two-step procedure. 1st operation: Soft tissue releases combined with the implantation of the THA components and placement of the external distraction apparatus. In the interval period slow iliofemoral distraction of 1mm–1.5 mm per day was conducted. Neurovascular signs and distraction was regularly monitored until the desired length was achieved. 2nd operation: the external fixation device was removed before applying the acetabular PE-inlay and the femoral head. Subsequent reduction was easy in most cases.

Results: A distraction of 51 mm (41 mm–75 mm) in 61 days (32–94 days) with an indicated speed of 1–1.5 mm/d and an effective speed of 0.8 mm (0.4 mm/d–1.8 mm/d) was achieved. Treatment time was 86 days (50–210 days). Patients had to maintain 132 days (40–300 days) restricted weight bearing. 2.6 (2–6) interventions were performed until final reduction. Harris Hip Score increased by 43 points [44 (22–65) to 83 points (66–98)]. The patients showed satisfying increases in all dimensions of the SF-36 health score. In the course of treatment pin-instability was seen in 6 cases, 3 minor intraoperative femoral fractures, 3 infections and 3 nerve damages occurred.

Discussion: The experiences of this study state the difficulties in the treatment of high DDH. The complication rate was high, but patients seemed to be satisfied finally. However, final scores were lower than in patients undergoing hip arthroplasties for degenerative osteoarthritis. Results of this treatment can be improved by avoiding certain pitfalls like insufficient soft tissue release, trans-cortical placement of the iliac screws or fast distraction. Nevertheless, soft tissue release and continuous iliofemoral distraction is the only option to restore limb-length and to preserve neurologic structures in cases with a dislocation over 40 mm.

Introduction: The number of revision Total Hip Arthroplasties (rTHA) continues to rise in an ageing population. High fracture rates reported point out that stem removal is associated with substantial surgical complications. Extensive Trochanteric Osteotomies (ETO) may facilitate stem removal; however, it has also been associated with hazards like increased incidence of non-union, fracture of the osteotomy fragment and stem subsidence. It is not yet clear if a permissive indication for ETO may lead to better postoperative results, than removing stem and cement from the top of the femur eventually causing fractures.

This study describes our experience, comparing peri-operative femoral fractures during stem removal with ETOs in rTHA.

Patients & Methods: Between 1992 and 2004 45 perioperative fractures during rTHA were compared to a collective of 28 ETOs. Pre-Op and after a follow-up period of 32 months (range, 21.6 – 76 months) patients were examined clinically and radiographically. Investigation parameters were Harris-Hip score, SF-36 health score, function (0 – 6) and pain (0 – 10) score, limp, postoperative complications, implant survival and radiographic parameters (stem and trochanter migration, stem alignment, bone union). Fractures were graded using the Vancouver classification.

Results: Harris hip score increase was 31 points (p = 0.004) in ETO patients and 17 points in patients with femoral fractures during stem removal. Increase for function and pain was 1.5 points and 4.4 points in ETO patients and 2 points and 3 points in patients with perioperative femoral fractures. SF-36 health score showed better increases in patients with ETOs. Joint luxation occurred in 3 (6.7%) patients with perioperative fractures and once (3.6%) in the osteotomy group. Infections were more frequently after ETO. 2 patients showed Trendelenburg gait after ETO, but were satisfied with the operation. 1 (3.6%, 12 mm) stem in the ETO group and 3 (6.7%, mean 15 mm) stems in the fracture group subsided slightly. No cable failure was detected in the ETO group, but 2 (4.4%) in the fracture group. 1 osteotomy fragment and 3 femoral fractures showed nonunion and needed re-revision. Every implanted stem had excellent alignment within standard error of ± 3°.

Discussion: Our results suggest that permissive indication for ETO in rTHA may lead to better postoperative results. Especially in patients with poor bone stock, where intraoperative fractures may likely occur, proper implant exposure and rigid fragment fixation may be crucial for success. Although the ETO might be associated with nonunion and limp, this study, as well as others, demonstrates that these observations do not necessarily compromise patient satisfaction. Conclusively, risking femoral fractures during stem removal is prejudicially, compared to proper, extensive femoral osteotomies in rTHA.

Introduction: Revision in total hip arthroplasty (THA) continues to be a technical challenge because of difficulties in fixation of the femoral component in mostly deficient bone in the proximal femur. In the past, the use of primary stems in revision surgery has also been described by many authors. Very often, the cortical bone is not sufficient enough for torsional or axial load bearing. In this retrospective study we present our clinical results of femoral component revision surgery using the uncemented primary BiCONTACT stem (Aesculap).

Methods: In this study, seventy-nine patients were examined who underwent a revision of the femoral component in total hip arthroplasty (THA) with the uncemented primary BiCONTACT stem between December 1991 and April 2004 (mean follow-up 6.8+/−3.9 years). Only patient with a defect classification of Paprosky I–II were analysed. The average patient age was 67.1+/−10.1 years (range from 34–87 years). Forty-six female and thirty-three male patients (168+/−10 cm mean height, 75+/−12 kg mean weight, mean Body Mass Index: 26.4+/−2.5) were included in the study. All patients were clinically evaluated both preoperatively and postoperatively using the Harris Hip Score (HHS), a pain score (from 0 [no pain], to 10 [max. pain]) and a motion score (from 0 to [no flexion], to 10 [max. flexion]). Furthermore, the radiographs (anteroposterior and axial) before, after surgery and at follow-up were analysed concerning femoral defects, proximal bone loss, and to determine the quality of bony fixation. The defects were classified using the Paprosky classification. For statistical analysis, the paired Student t-test was used for preoperative and postoperative data.

Results: The postoperative Harris Hip Score (78.9+/−12.5, p < 0.001), Range of Motion Score (p < 0.05) and Pain Score (p =0.005) improved significantly. During follow-up there were only four re-revisions within two years after revision surgery: two re-infections in the first year, two aseptic loosening in the second year. There were only two cases of mild stress shielding. The survival curve (Kaplan-Meyer) showed a 10-years survival rate of 96.2 %. In two cases we found intraoperative periprosthetic fractures and in fourteen cases small fissures during removal or implantation of the stem.

Discussion: The primary uncemented BiCONTACT stem appears to be a good alternative to other revision systems in well-selected femoral revision cases with minor defects. The results of this study correspond to those published before, using a primary cementless stem in cases of revision. Therefore, in cases of minor proximal and metaphyseal bone defects (Paprosky I–II) the use of a primary stem in femoral revision should be considered. However, an exact preoperative planning, intraoperative assessment of bone stock, and experienced surgeon is necessary.

Introduction: Periprosthetic fractures occurring during implantation of non-cemented Total Hip Arthroplasty (THA) are considered major surgical complications. As a shot-term disadvantage, patients are required to partially weight-bear. Additionally, high risks of stem migration and joint luxation can be assumed. On the other hand, in fear of fracture surgeons may undersize stems and subsequently trigger failure rates in THA.

As the long-term consequences of Vancouver A and B1 fractures are not fully known, the goal of this study now was to analyze the postoperative performance of non-cemented THA with respect to perioperative fractures.

Materials and Methods: Between 1997 and 2003 41 peri-operative hip fractures were monitored in 1216 primary Total Hip Arthroplasties using the non-cemented Bicon-tact THA stem. Pre-OP and after a follow-up period of 2,2 (+−3,1) years patients were examined clinically and radiographically. Investigation parameters were Harris-Hip-Scores, SF-36 scores, function score, hospitalization, implant survival /revisions and radiographic parameters (stem migration, trochanter migration, osteolysis, bone union, callus formation and bone quality). Fractures were graded using the Vancouver and Mont+Maar classifications. Patients were compared to a comparable collective of THA patients without perioperative fractures. Pooled data of both groups were compared using non-parametric Kruskal-Wallis tests.

Results: Results showed a significant increase in Harris-Hip scores for all THA of 36 (+−17,7) points. There were no differences in function scores (2,3; score 1–6), postoperative pain (4,8; score 1–10), and time of hospitali-sation (21,3d; +−3,7 range, 14 – 32). The non-union rate was 13%, with 85% of trochanteric fractures showing migration. 47% of the Patients in the fracture group were instructed to maintain restricted weight bearing for 6 weeks. No Trendelenburg signs were observed in the fracture group. Stem migration of mean 0,6 cm (+−0,4) was observed in 13% of Vancouver A and B1 patients (6,4% of A, 20,1% of B1). Long-term cerclage wire failure was observed in 20%. Joint luxation was observed in 1 patient. No hips were revised during the follow-up period.

Discussion: Follow-ups of perioperative fractures classes Vancouver A and B1 during non-cemented THA using the Bicontact stem show associations with stem migration, long-term stabilization implant failure and non-union. However, none of these observations seem to be influencing the overall THA performance and patient satisfaction. Specifically, complications commonly associated with perioperative primary prosthetic fractures as luxation and limping were not signifi-cant. At a short-term perspective, perioperative THA fractures prohibit early weight-bearing. However at a mid to long-term perspective, no disadvantages were apparent in comparison to primary THA without fracture complications.