A new minimal-invasive approach for total hip replacement in sheep.

BACKGROUND: Over the last 50 years arthroplasty became the gold-standard treatment for disabling conditions of the coxofemoral joint. Variations of anterior, lateral, and dorsal incision have been applied, but as each approach requires the incision and reflection of various muscles to gain adequate exposure of the joint results are still controversial. OBJECTIVE: The purpose of this study was to develop a minimal-invasive, tissue-sparing approach in sheep with reduced risks in animal testing. METHODS: 12 mature sheep underwent hip surgery as part of a study to evaluate a hip resurfacing system. In line with the preliminary cadaveric tests a modified, minimal-invasive, musclepreserving surgical approach was sought after. RESULTS: We developed a surgical approach to the coxofemoral joint in sheep using only blunt tissue dissection after skin incision without any limitations in joint exposure or increased blood loss/duration of surgery. CONCLUSION: Even though limitations occur and femoral orientation in sheep differs from man, joint forces have similar relative directions to the bone with similar bony and vascular anatomy. Therefore, this minimal-invasive muscle preserving approach might be a safe and comparable alternative in still inevitable animal testing.

Development of a novel biodegradable porous iron-based implant for bone replacement.

Bone replacement and osteosynthesis require materials which can at least temporarily bear high mechanical loads. Ideally, these materials would eventually degrade and would be replaced by bone deposited from the host organism. To date several metals, notably iron and iron-based alloys have been identified as suitable materials because they combine high strength at medium corrosion rates. However, currently, these materials do not degrade within an appropriate amount of time. Therefore, the aim of the present study is the development of an iron-based degradable sponge-like (i.e. cellular) implant for bone replacement with biomechanically tailored properties. We used a metal powder sintering approach to manufacture a cylindrical cellular implant which in addition contains phosphor as an alloying element. No corrosion inhibiting effects of phosphorus have been found, the degradation rate was not altered. Implant prototypes were tested in an animal model. Bone reaction was investigated at the bone-implant-interface and inside the cellular spaces of the implant. Newly formed bone was growing into the cellular spaces of the implant after 12 months. Signs of implant degradation were detected but after 12 months, no complete degradation could be observed. In conclusion, iron-based open-porous cellular biomaterials seem promising candidates for the development of self-degrading and high load bearing bone replacement materials.

Effects of Whole Body Vibration Therapy and Classic Physiotherapy on Postural Stability in People With Back Pain: A Randomized Trial.

STUDY DESIGN: This 2-step prospective randomized parallel trial evaluated postural stability in 65 back pain participants (61.6±7.9 y) and 50 nonback pain participants (61.2±8.6 y) in a first step using the MFT-S3-Check. In a second step, postural stability and questionnaires were evaluated in back pain participants before and after therapy with either whole body vibration therapy or classic physiotherapy. OBJECTIVE: The first aim was to investigate whether the MFT-S3-Check is suitable to evaluate differences in postural stability in back pain and nonback pain participants. The second aim was to evaluate the effect of whole body vibration therapy and classic physiotherapy on postural stability and the influence of depressive symptoms and pain. SUMMARY OF BACKGROUND DATA: Objective bodily measurement values in chronic back pain are rare; therefore, the evaluation of effectiveness of different therapies is difficult. METHODS: Postural stability was investigated using stability-, sensorimotor-, and symmetry indexes, in standing and seated positions with the MFT-S3-Check. The following standard questionnaires were used to investigate pain and depressive symptoms: HADS, ODI, NASS, SF-36. RESULTS: No significant difference in postural stability was found between back pain participants and the nonback pain group. None of the two training concepts in back pain participants was superior, concerning postural stability and pain. Both treatments showed positive effects, with significant improvements in postural stability in the classic physiotherapy group. Depressive symptoms had a significant correlation with pain intensity in back pain participants. CONCLUSIONS: The MFT-S3-Check could not find a significant difference in postural stability between the back pain and nonback pain group in the study setting. Postural stability improved after treatment.

Discrepancy between morphological findings in juvenile osteochondritis dissecans (OCD): a comparison of magnetic resonance imaging (MRI) and arthroscopy.

PURPOSE: The aim of this study was to assess the reliability of preoperative MRI for the staging of osteochondritis dissecans (OCD) lesions of the knee and the talus in juvenile patients, using arthroscopy as the gold standard of diagnosis. METHODS: Sixty-three juvenile patients (range 8-16 years) with an OCD of the knee or the talus underwent arthroscopy after MRI. In 54/9 out of 63 cases, 1.5/3 T MR scanners were used. The OCD stage was classified according the staging criteria of Dipaola et al. Arthroscopic findings were compared with MRI reports in each patient. RESULTS: From the 63 juvenile patients, MRI/arthroscopy revealed a stage I OCD in 4/19 patients, stage II in 31/22 patients, stage III in 22/9 patients and stage IV in 6/6 patients. No osteochondral pathology was evident in arthroscopy in seven out of 63 patients. The overall accuracy of preoperative MRI in staging an OCD lesion of the knee or the talus was 41.3%. In 33 out of 63 patients (52.4%), arthroscopy revealed a lower OCD stage than in the preoperative MRI grading, and in four out of 63 cases (6.4%), the intraoperative arthroscopic grading was worse than in preoperative MRI prior to surgery. The utilization of the 3 T MRI provided a correct diagnosis with 44.4%. CONCLUSIONS: Even with today's modern MRI scanners, it is not possible to predict an accurate OCD stage in children. The children's orthopaedist should not solely rely on the MRI when it comes to the decision to further conservative or surgical treatment of a juvenile OCD, but rather should take surgical therapy in consideration within persisting symptoms despite a low OCD stage provided by MRI. LEVEL OF EVIDENCE: III.