The glenohumeral joint is a remarkable articulation providing the greatest range of motion of any joint in the body. Glenohumeral stability results from several mechanisms, including those that do not require expenditure of energy by muscle ("passive mechanisms") and those that do ("active mechanisms"). Glenohumeral instability has been recognized in 47 shoulders of 45 dogs and one cat. Cases are presented because of chronic foreleg lameness. Shoulder joint pain is obviated by the orthopedic examination. Only 57% of the involved shoulders presented with degenerative joint disease. Signs of instability are recognized under anesthesia using a craniocaudal or mediolateral drawer sign or both. This report describes the radiographic and arthroscopic findings of shoulder instability. Arthroscopy of the shoulder joint allows identification of all intra-articular pathologies. Shoulder instability, not fully recognized in the past, appears to be the most common cause of shoulder lameness in the dog.

Case histories of 130 dogs and cats with humeral fractures were reviewed. The different types of fractures were classified. Most animals with proximal, shaft, and supracondylar fractures had excellent results. The poor prognosis associated with distal articular fractures was due most often to failure of the fixation device in the supracondylar area; best results were achieved with a plate on the caudal and medial surface of the distal humerus. R O X I M A L A N D MIDSHAFT HUMERAL fractures in P veterinary patients have been repaired with in-

The authors defined the concept of femoral torsion using three axes and two planes. Two techniques were used to measure the femoral anteversion angle on 30 femurs of 15 adult mixed breed dogs. The conventional fluoroscopic technique was compared to the right angle triangle technique. The mean angle for each technique was 30.80 and 31.31 degrees, respectively. The right angle triangle technique, using conventional radiographs, appeared as reliable, accurate, and reproducible as the fluoroscopic method and is recommended for clinical use.

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OBJECTIVES Large retrospective series have indicated lower rates of cN0 to pN1 nodal upstaging after video-assisted thoracic surgery (VATS) compared with open resections for Stage I non-small-cell lung cancer (NSCLC). The objective of our multicentre study was to investigate whether the presumed lower rate of N1 upstaging after VATS disappears after correction for central tumour location in a multivariable analysis. METHODS Consecutive patients operated for PET-CT based clinical Stage I NSCLC were selected from prospectively managed surgical databases in 11 European centres. Central tumour location was defined as contact with bronchovascular structures on computer tomography and/or visibility on standard bronchoscopy. RESULTS Eight hundred and ninety-five patients underwent pulmonary resection by VATS (n = 699, 9% conversions) or an open technique (n = 196) in 2014. Incidence of nodal pN1 and pN2 upstaging was 8% and 7% after VATS and 15% and 6% after open surgery, respectively. pN1 was found in 27% of patients with central tumours. Less central tumours were operated on by VATS compared with the open technique (12% vs 28%, P < 0.001). Logistic regression analysis showed that only tumour location had a significant impact on N1 upstaging (OR 6.2, confidence interval 3.6–10.8; P < 0.001) and that the effect of surgical technique (VATS versus open surgery) was no longer significant when accounting for tumour location. CONCLUSIONS A quarter of patients with central clinical Stage I NSCLC was upstaged to pN1 at resection. Central tumour location was the only independent factor associated with N1 upstaging, undermining the evidence for lower N1 upstaging after VATS resections. Studies investigating N1 upstaging after VATS compared with open surgery should be interpreted with caution due to possible selection bias, i.e. relatively more central tumours in the open group with a higher chance of N1 upstaging.