Short-stem total hip arthroplasty (THA) has primarily been recommended for young and active patients, mainly due to its bone preserving philosophy. Elderly patients, however, may also benefit of a minimally invasive technique due to the short and curved implant design. The purpose of this study was to compare the clinical and radiological outcomes as well as perioperative complications of a calcar-guided short stem between a young (75 years) population.

Data were collected in a total of 5 centers, and 400 short stems were included as part of a prospective multicentre observational study between 2010 and 2014 with a mean follow-up of 49.2 months. Clinical and radiological outcomes were assessed in both groups. Secondary outcomes such as perioperative complications, rates and reasons for stem revision were also investigated.

No differences were found for the mean visual analogue scale (VAS) values of rest pain, load pain, and satisfaction. Harris Hip Score (HHS) was found to be slightly better in the young group. Comparing both groups, no statistically significant differences ere found in the radiological parameters that were assessed (stress-shielding, cortical hypertrophy, radiolucency, osteolysis). Aseptic loosening was the main cause of implant failure in younger patients whereas in elderly patients, postoperative periprosthetic fractures due to accidental fall was found to be the main cause for stem revision.

These short-term results are encouraging towards the use of a cementless short stem in the geriatric population. According to our findings, advanced age and potentially reduced bone quality should not necessarily be considered as contra-indications for calcar-guided short-stem THA but careful and reasonable selection of the patients is mandatory. Longer follow up is necessary in order to draw safer conclusions.

Although the number of displaced femoral neck fractures treated with hip arthroplasty is steadily growing, the outcomes are not as good as for other surgical indications. As a result, there is no consensus on the ideal type of arthroplasty for these patients. Unipolar and bipolar arthroplasty have a low dislocation rate but implant longevity and functional results are suboptimal. Total hip arthroplasty (THA) provides better functional outcomes and implant longevity but it is associated with a high incidence of postoperative dislocation. This constitutes a significant limiting factor for a more widespread use of this procedure.

The TriboFit^® Buffer (Active Implants Corporation, Memphis, Tennessee, USA) is a 2.7 mm-thick cup made of polycarbonate-urethane which mimics the mechanical characteristics of human cartilage. It is a pliable, hydrophilic, biocompatible, endotoxin-resistant material and acts as a stress-absorber, transmitting loads to the subchondral bone in a physiological manner. The TriboFit^® Buffer shows excellent tribology, including ideal fluid film lubrication, low friction, high load carrying capabilities and long endurance.

The TriboFit^® Buffer is fixed using flexible mechanical fixation. With a special instrument, a circumferential groove is cut into the patients’ socket. The TriboFit^® Buffer is seated by applying gentle pressure, with its ledge snapping tightly into the groove. The surgical technique is bone sparing as no acetabular bone reaming is required whatsoever. The TriboFit^® Buffer can be coupled with large diameter cobalt-chromium femoral prosthetic heads of the same dimensions as the patients’ femoral head. By restoring the correct hip anatomy and preserving the original size of the femoral head, hip range of motion (ROM) and stability are optimised.

Within a multi-centre study, 224 patients (63 male and 161 female) with femoral neck fractures were treated with the TriboFit^® Buffer, a large diameter head and either cemented (192) or uncemented femoral stems (32). The mean patient age was 83 years (range 65 to 96).

All surgeries were performed using a standard antero-lateral approach.

Rehabilitation was fast and weight-bearing was as tolerated by the patients. There were no major complications, and in particular, no postoperative dislocations were reported.

At a mean follow-up of one year, X-rays showed good implant stability. The mean Harris hip score (HHS) after one month was 58 points and increased to 80 points at one year (p = < 0.05). The ROM was the same as in the intact hip. Only one patient was revised because of nonimplant-related pain. This patient complained of pain in the surgically treated limb which was in actual fact related to spinal stenosis. Analysis of the retrieved implant revealed a loss of thickness in the superior area as well as minimal weight (approximately 2.4%). The backside revealed evidence of macroscopic wear in the area of directional loading from the femoral head to the acetabulum. The bearing surface showed minimal wear (less than 15 mm3), indicating that the primary wear location was on the backside. Retrieved synovial fluid and tissue analysis confirmed that there was no reactivity and no sign of synovitis.

With femoral neck fracture patients, TriboFit^® Buffer arthroplasty is theoretically superior to both hemiarthroplasty and THA as it should involve the same low risk of dislocation and acetabular bone preservation associated with hemiarthroplasty, together with the same good functional results and consistent implant longevity of THA. Other advantages of this technique include reduced bleeding and short surgical times.

The results of this study show that the new TriboFit^® Buffer arthroplasty technology has the potential to revolutionize the surgical treatment of displaced femoral neck fracture.

Introduction: Rheumatoid arthritis and osteoarthritis as well as other diseases can cause severely destruction of the finger joints. The treatment is surgical replacement with joint prosthesis manufactured from flexible silicone or other materials. Silicon prostheses (Swanson’s prostheses) are used worldwide already since 1974. However, the material used may not be strong enough on long term and several reports from breakdown of the prostheses have been published. The long-term results have also shown that bony resorption around the implant may occur. The known weaknesses of the current endoprostheses have lead researchers to look for new materials.

Material: In the beginning of 1994 a fibrous cushion made of commercially available biodegradable fibres (Vicryl® and Ethisorb®) was introduced by the group of researchers from Tampere University Hospital in Finland. It was intended to act as the tendon in Vainio arthroplasty and the aim was to find a material that could work as a scaffold for the collagenous proliferation of connective tissue or fibrocartilage. However the resorption time on the material was too short, which led to the premature collapse of the joint space.

Novel scaffolds were developed using a well-known poly-L/D-lactide copolymer with L/D-monomer ratio 96/4 (PLDLA) in collaboration with the Institute of Biomaterials at Tampere University of Technology and Tampere University Hospital. The PLDLA scaffolds are fibrous, porous cylinders enabling the in-growth of fibrous tissue, which then ideally forms a new, functional joint for the patient. Meltspun PLDLA scaffolds retain 50% of their strength at least 13 weeks in vitro. This enables to retain the shape and size of the scaffolds in situ long enough for tissue ingrowth. The scaffold will bioabsorb and be replaced with fibrous tissue in approximately 2–3 years.

Method: Since January 2003 we take part in a prospective randomised international multicenter study, that is supported by the European Commission. The new bioreplaceable devices are implanted in hands (CMC, MCP, PIP und DIP) as well as feet (MTP I–V toe joints) and will be compared to the standard treatments (Swanson Prostheses, Arthrodeses). The study is surveyed by an Ethical Committee.

Results: Up to now we implanted the bioreplaceable scaffolds in several joints of hands with good results. In future we will also use them for metatarso-phalangeal joints in feet. We will present in the meeting our experiences and outcomes so far.

Introduction The NexGen-CR-Knee System ( Zimmer, Inc.) was developed for cruciate ligament retaining TKA, preserving as much of the function of the normal knee as possible. It was cleared by the FDA in 1995. Prerequisites are good bone quality and intact ligaments. It is part of a modular system for primary and some revision cases with a large selection of sizes, augmentation blocks and stem extensions.

Material In the Orthopedic Center in Kassel about 1500 NexGen Cr devices were implanted and documented since October 1998. The 5-in-1 milling system was used and all components were cemented. Prospective evaluation pre-, intra- and postoperatively, at 1, 2 and 5 years was performed with a low drop out rate. 232 consecutive cases will have the 5 year data. The outcome will be presented, among others the Knee Society Score (function & knee), range of motion, complications and reasons for revisions. Comparison with the worldwide register of this implant is made.

Conclusion The NexGen CR Knee Solution implants and the technique of implantation appear to be very successful in mid term results. It is a good basis for further developments such as highly crosslinked Polyethylene and the new CR Flex design.