Pelvic tilt makes navigation systems referring to the anterior plane inaccurate.

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This study evaluates forces underneath the coracoacromial vault during elevation of the arm, using a dynamic shoulder model. Muscle forces at the glenohumeral joint were simulated with hydrodynamic cylinders and applied to the deltoid muscle and to the rotator cuff through wire cables in ten anatomic specimens. Computerized regulation initiated precise, time-controlled cycles of glenohumeral joint motion. The position of the arm in all spatial orientations was measured with an ultrasonic device. Forces underneath the coracoacromial vault were recorded with capacitive sensors. The mean force during one cycle of elevation averaged 13.9 N 2 12.5 N underneath the acromion, 0.43 N ? 0.51 N underneath the coracoacromial ligament, and 3.44 N 2 4.37 N underneath the coracoid process. The peak force averaged 37.8 N 2 33.2 N underneath the acromion, 3.03 N 2 2.62 N underneath the coracoacromial ligament, and 6.93 N ? 7.38 N underneath the coracoid process. Forces under the coracoid process exceeded forces under the acromion in some specimens. A marked increase in forces was observed a t the final stage of arm elevation and during early reverse-elevation in most specimens. The authors believe that these force values represent the pathomechanics of the shoulder impingement syndrome.

The comparability of studies of extra-articular proximal femur fractures is compromised by the lack of a widely accepted, simple classification system with clinical and prognostic relevance. The aim of the study is to define the complication profile as well as differences relating to age, gender and survival rate of simple trochanteric fractures, intertrochanteric comminuted and subtrochanteric fractures. Records of 335 consecutive patients were analysed. Patients had a median follow-up of 10 (1-56) months, and were treated operatively with three intramedullary nailing systems. Simple trochanteric fractures (n=67) show wound healing problems (1.5%). Median age is m/f 77(45-98) years/ 85(39-101), and two-year survival rate is m/f 50.3%/ 84.9%. Intertrochanteric comminuted fractures (n=204) show the highest complications (25%), 9.7% femoralhead perforations, 3.5% hardware related problems and 11.8% wound healing problems. Median age is m/f 75(41-94) years/ 85(54-100), survival rate is m/f 92.7%/ 66.5%. Complication rate is 17.0% in subtrochanteric fractures (n=64), no femoralhead perforation but 9.1% other hardware problems and 7.8% wound healing problems. Median age is m/f 72(24-91) years/ 83(38-99), survival rate is m/f 92.3%/ 67.9%. Females show higher complication rates compared to males (19% versus 10%). The three types of fractures show different patterns of complications, survival rates, age, and sex distribution.