Aim

In the last years, many short hip stem variants were developed, almost always sharing the principle of metaphyseal and proximal diaphyseal anchorage. In this study, we analyzed the midterm results after implanting short cementless hip stem of ESKA.

A large number of short stem prosthesis for hip arthroplasty has been introduced in the last years. The main aim of this device is to preserve the proximal bone stock in order to facilitate revisions in the future. Furthermore there is an increase in young and active patients in total hip arthroplasty that's why it's important to consider minimally invasive, muscle-considering procedures. Short stems allow to make minimal invasive approaches easier and improve the biomechanical reconstruction. However, there is a large increase of publication about short stems there is still little data about survival and revision rates. We report about the outcome of 81 patients, who have recieved NANOS short stem prosthesis between October 2012 and April 2014. The average age of the patient was 61,6. The oldest patient was 78 years old and our youngest patient was 41 years old. The main diagnoses were osteoarthritis in 67 patients, dysplastic osteoarthritis in 8 patients and avascular necrosis of the femoral head in 6 patients. We have included 37 female patients and 44 male patients. 3 patients had the surgery on both sides. The average operating time was 75,2 min ± 20,1 min and the average grading of patients for surgical procedures of the American Society of Anesthesiologists was 1,8±0,7. The patients were hospitalized 9,6 days ± 2,9 days. The average BMI was 28,2±5,2. Along with demographic data and co-morbidities, the Harris Hip Score was recorded pre-operatively and at follow-up. The Harris Hip Score increased from 36,6 ± 14,5 pre-operatively to 94,5 ± 8,8 at the final follow-up. None of the 81 stems were revised this corresponds to a to a survival rate of 100%. Two of the patients suffered from a hip dislocation which was treated in both cases conservative. In further consequence unfortunately one of those patients thrombosed and suffered from a pulmonary embolism. The x-rays haven't shown any radiolucent lines in any patients. All in all our patients reported about an high post-operative satisfaction. The clinical and radiographic results encouraged us to continue to use short stems with metaphyseal anchorage. However, there must be more long-term results to confirm our excellent mid term results

Introduction:. Total hip arthroplasty has became one of the most successful standard procedures in the orthopaedic surgery. With a more frequent use in young and active patients bone saving procedures become more important. On the other hand, the ever increasing trend toward minimal excision of the healthy bone during implantation of the total hip replacement has led to a range of implants that can be classified according their means of anchorage in the various anatomic segments. The Nanos-short-stem endoprothesis presented here requires metaphyseal anchorage. Material and methods:. From juli 2005 to march 2009 a total of 112 (70 males, 52 female) uncemented Nanos-short-stem prothesis were implanted in 111 patients in Westpfalz academic hospital –University Mainz. The patiens average age was 53 years (33–73). The indication for this procedure was predominantly coxarthrosis. In all cases dorsal approach was used. The mean follow up period was 2,5 years (range 6 months–4,5 years). The patients were assessed using Harris Hip Score and radiologically to detect any bone changes, the stand of the prothesis and peri-articular ossifications. Results:. The perioperative Harris Hip Score was 53 (28–77), postoperative was 94 (86–100). We did not have discovered any prothesis specific complications. Radiological follow up examinations showed the development of increasing trabecular reinforciment of the femoral neck and pertrachanteric regions. There is no evidence of any loosing or migration of the prothesis. Conclusion:. the stem design of Nanos-short-stem prothesis allowed a metaphyseal intertrochanteric multipoint primary fixation. The surgical technique is simple. It offers alternative to convenential total hip arthroplasty especially in young patients and save bone stock for later revision (1–2). Long term studies still be needed

For younger patients many surgeons recommend femoral neck endoprostheses as alternative to stemmed implants in THA. Due to metaphyseal anchorage several advantages are quoted, e.g. preservation of the femoral diaphysis for a revision implant. Determinant factor for long-term implant stability is the load transmission to the bone. Because so far only few information about the load transfer of femoral neck endoprostheses exist, a photoelastic analysis was performed. Aim of the study was the comparison of bony strain pattern before and after implantation of a femoral neck endoprosthesis. ‘Composite-femurs’ (Pacific Research Labs) were used due to of their mechanical characteristics close to human femurs but better reproducibility. Three femurs were coated with photoelastic material. The femurs were loaded prior and post implantation of a femoral neck endoprosthesis type Cigar (ESKA Implants). Test load consisted of the resulting hip joint force and muscle forces (abductors, tractus iliotibialis). Load was applied statically by a universal testing machine and additional weights. Bony strain was measured along the medial, ventral, lateral and dorsal cortex. Statistical analysis of the implant related strain alterations was based on a 99% confidence interval. The unresected femurs showed an excellent match of bony strain patterns. Implantation of femoral neck endoprostheses caused highly significant strain changes at the trochanteric region. Greatest differences were observed at the lateral cortex. Above the implant’s traction screw former areas of tension changed to compression. Along the medial cortex below the resection plane strain reductions were measured but disappeared at the latest at 40 mm below. No significant changes in strain were detected at the ventral and dorsal cortex. Implant related bony strain alterations were limited to the trochanteric region of the femur. A marked strain alteration at the lateral trochanteric aspect was measured. Whether this is of clinical importance can not be answered yet