In this prospective study a total of 80 consecutive Chinese patients with Crowe type I or II developmental dysplasia of the hip were randomly assigned for hip resurfacing arthroplasty (HRA) or total hip replacement (THR).

Three patients assigned to HRA were converted to THR, and three HRA patients and two THR patients were lost to follow-up. This left a total of 34 patients (37 hips) who underwent HRA and 38 (39 hips) who underwent THR. The mean follow-up was 59.4 months (52 to 70) in the HRA group and 60.6 months (50 to 72) in the THR group. There was no failure of the prosthesis in either group. Flexion of the hip was significantly better after HRA, but there was no difference in the mean post-operative Harris hip scores between the groups. The mean size of the acetabular component in the HRA group was significantly larger than in the THR group (49.5 mm vs 46.1 mm, p = 0.001). There was no difference in the mean abduction angle of the acetabular component between the two groups.

Although the patients in this series had risk factors for failure after HRA, such as low body weight, small femoral heads and dysplasia, the clinical results of resurfacing in those with Crowe type I or II hip dysplasia were satisfactory. Patients in the HRA group had a better range of movement, although neck-cup impingement was observed. However, more acetabular bone was sacrificed in HRA patients, and it is unclear whether this will have an adverse effect in the long term.

A common location for radius fracture is the proximal radial head. With the arm in neutral position, the fracture usually happens in the anterolateral quadrant (Lacheta et al., 2019). If traditional surgeries are not enough to induce bone stabilization and vascularization, or the fracture can be defined grade III or grade IV (Mason classification), a radial head prosthesis can be the optimal compromise between bone saving and recovering the “terrible triad”. A commercially available design of radial head prosthesis such as Antea (Adler Ortho, Milan, Italy) is characterized by flexibility in selecting the best matching size for patients and induced osteointegration thanks to the Ti-Por. ®. radial stem realized by 3D printing with laser technique (Figure 1). As demonstrated, Ti-Por. ®. push-out resistance increased 45% between 8 −12 weeks after implantation, hence confirming the ideal bone-osteointegration. Additional features of Antea are: bipolarity, modularity, TiN coating, radiolucency, hypoallergenic, 10° self-aligning. The osteointegration is of paramount importance for radius, in fact the literature is unfortunately reporting several clinical cases for which the fracture of the prosthesis happened after bone-resorption. Even if related to an uncommon activity, the combination of mechanical resistance provided by the prosthesis and the stabilization due to the osteointegration should cover also accidental movements. Based upon Lacheta et al. (2019), after axial compression-load until radii failure, all native specimens survived a compression-load of 500N, while the failure happened for a mean compression force of 2560N. The aim of this research study was to test the mechanical resistance of a radial head prosthesis obtained by 3D printing. In detail, a finite element analysis (FEA) was used to understand the mechanical resistance of the core of the prosthesis and the potential bone fracture induced in the radius with simulated bone- resorption (Figure 2a). The critical level was estimated at the height for which the thickness of the core is the minimum (Figure 2b). Considered boundary conditions:. - Full-length prosthesis plus radius out of the cement block equal to 60mm (Figure 2a);. - Bone inside the cement equal to 60mm (Figure 2b);. - Load inclined 10° epiphysiary component (Figure 2c);. - Radius with physiological or osteoporotic bone conditions;. - Load (concentrated in the sphere simulating full transmission from the articulation) of 500N or 1300N or 2560N. Figure 3 shows the results in terms of maximum stress on the core of the prosthesis and the risk of fracture (Schileo et al., 2008). According to the obtained results, the radial head prosthesis shows promising mechanical resistance despite of the simulated bone-resorption for all applied loads except for 2560N. The estimated mechanical limit for the material in use is 200MPa. The risk of fracture is in agreement with the experimental findings (Lacheta et al. (2019)), in fact bone starts to fail for the minimum reported failure load, but only for osteoporotic conditions. The presented FEA aimed at investigating the behavior of a femoral head prostheses made by 3D printing with simulated bone-resorption. The prosthesis shows to be a skilled solution even during accidental loads. For any figures or tables, please contact the authors directly

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

Introduction: Rheumatoid arthritis often leads to severe destruction of the glenohumeral joint including synovitis and inflammation induced alterations of the rotator cuff. Cup arthroplasty, or surface replacement of the shoulder was introduced in the 1980s. The aim of this study was to confirm or withdraw the very promising results of the DUROM-Cup surface replacement for patients with rheumatoid arthritis. Patients an Methods: From 1997 to 2000 a cohort of 42 DUROM-Cup hemiprotheses were implanted in 35 patients. The patients were evaluated preoperatively and after 3,12 and more than 60 month postoperatively. 7 patients were lost to follow up. A total of 35 DUROM-Cups (29 patients) could be examined prospectively after an average follow up period of 73.1 (+/− 12.1) month (Average age 61.4y, female n=21, male n=68). Rotator cuff defects were classified intraoperatively. Results: Three revisions occured: One due to a too large implant, one due to glenoid erosion and one due to loosening of the implant. The constant score increased from preoperatively 20.8 points to 64.3 points at a mean follow up of 73.1 month. No differences were seen in patients with massive cuff tears. In these cases the cup was implanted in a more valgic position, so that articulation with the acromion could be achieved. The radiographic results did not show any changing of the parameters for the position of the cup. No further endo-prosthetic loosening was observed. The proximal migration increased in 66% and the glenoid depht increased in 37% of the cups. Discussion: The results of the cemented DUROM-Cup surface replacement for patients with advanced rheumatoid arthritis of the shoulder are very encouraging, especially in patients with massive tearing of the rotator cuff. The advantages of cup arthroplasty are to be found in the reduced level of invasive surgery and the simpler technique with bone saving fixation. In the event of failure of the implant good further treatment options for salvage procedures remain

The minimally invasive total hip replacement has been developed over the last years. The advantages of minimally invasive approaches concern reduced blood loss and pain, shorter operative time, reduced length of stay, facilitated rehabilitation and increased patient satisfaction. Potential disadvantages are the need for additional training and patient education, the insufficient clinical data and the risk of compromising the final result by giving more importance to the length of incision than to the damage of the deeper tissue. In the majority of cases, the minimally invasive techniques utilize standard prosthesis and resection of pathological tissue, including part of normal bone such as the femoral neck. LINK MIT-H permits combining a minimally invasive approach with the insertion of a T.O.P. acetabular cup and a CFP femoral prosthesis, preserving the femoral neck. The conservation of this anatomic part facilitates a shallow entry of the prosthesis in the femoral canal, preserving the bone stock and thereby allowing a more precise reconstruction of the hip geometry. The technique appears to give good results, associating the advantages of minimally invasive surgery with the preservation of the femoral neck. The good relation between the abductor lever arm and the adductor lever arm guarantees an elevated functional restoration, allowing a favorable and durable result in time. The LINK MIT-H technique may be utilized with a direct lateral or through a post-lateral approach. We prefer a lateral approach, usually utilizing general instruments such as hooks and Hohmann retractors where the width of instruments is adapted to the length of incision. A corkscrew may be useful to take out the femoral head, cutting it in the narrow part of the neck. Stein-mann pins, placed at the cranial acetabular rim as self-retaining retractors, associated with two Hohmann retractors below, allow good vision and facilitate reaming the socket. The attachment of fibre optics on the retractors is useful to have more light inside. Straight or cranked shaft instruments are very well suited in reaming and in aligning the T.O.P. acetabular cup. The minimally invasive technique gives the best results when damaging tissues as little as possible by using a less invasive prosthesis that is easily implanted in small spaces and only replaces the pathologic bone, thereby saving the bone stock best as possible in restoring the hip geometry