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.

Radiographic changes and clinical outcomes after open and closed wedge high tibial osteotomy: a systematic review and meta-analysis.

BACKGROUND: The purpose of this meta-analysis is to examine changes in radiological variables and clinical outcomes between open and closed wedge high tibial osteotomy (OWHTO and CWHTO, respectively), which have ongoing controversial issues in numerous quantitative clinical studies. METHODS: PubMed, Embase, and the Cochrane Library were systematically searched for suitable controlled trials between Jan 1, 1999, and Feb 2, 2018. The inclusion criteria included studies written in English, studies with a level of evidence of I-IV, and studies presenting comparisons between OWHTO and CWHTO. The main clinical and radiographic results were extracted and pooled using Stata 12.0. RESULTS: After searching for and screening trials, 28 trials involving 2840 knees were eligible for the meta-analysis. After OWHTO or CWHTO, clinical scores, including the American Knee Society Score, Hospital for Special Surgery Knee Score, Lysholm score, and Visual Analog Scale pain score, improved (p < 0.05), but the range of motion was unchanged (p > 0.05). The anatomical femorotibial angle (SMD 0.04, 95% CI - 0.66 to 0.74) and hip-knee-ankle angle (SMD 0.11, 95% CI - 0.11 to 0.33) data suggested that the OWHTO and CWHTO groups were similar in function of correction. Posterior tibial slope increased (SMD - 0.71, 95% CI - 1.04 to - 0.37) after OWHTO but decreased (SMD 0.72, 95% CI 0.35 to 1.08) after CWHTO. OWHTO decreased patellar height (p < 0.05), while patellar height did not change significantly after CWHTO (p > 0.05). CONCLUSION: This meta-analysis indicates that compared with CWHTO, OWHTO increases the posterior slope, decreases the patellar height, and provides a similar accuracy of correction; however, CWHTO leads to a decreased posterior slope and an unchanged patellar height. Therefore, programs should be personalized and customized for the specific situation of each patient.

PMMA third-body wear after unicondylar knee arthroplasty decuples the UHMWPE wear particle generation in vitro.

INTRODUCTION: Overlooked polymethylmethacrylate after unicondylar knee arthroplasty can be a potential problem, since this might influence the generated wear particle size and morphology. The aim of this study was the analysis of polyethylene wear in a knee wear simulator for changes in size, morphology, and particle number after the addition of third-bodies. MATERIAL AND METHODS: Fixed bearing unicondylar knee prostheses (UKA) were tested in a knee simulator for 5.0 million cycles. Following bone particles were added for 1.5 million cycles, followed by 1.5 million cycles with PMMA particles. A particle analysis by scanning electron microscopy of the lubricant after the cycles was performed. Size and morphology of the generated wear were characterized. Further, the number of particles per 1 million cycles was calculated for each group. RESULTS: The particles of all groups were similar in size and shape. The number of particles in the PMMA group showed 10-fold higher values than in the bone and control group (PMMA: 10.251 × 10(12); bone: 1.145 × 10(12); control: 1.804 × 10(12)). CONCLUSION: The addition of bone or PMMA particles in terms of a third-body wear results in no change of particle size and morphology. PMMA third-bodies generated tenfold elevated particle numbers. This could favor an early aseptic loosening.