Asphericity of the femoral head-neck junction is common in cam-type
femoroacetabular impingement (FAI) and usually quantified using
the alpha angle on radiographs or MRI. The aim of this study was
to determine the natural alpha angle in a large cohort of patients
by continuous circumferential analysis with CT. CT scans of 1312 femurs of 656 patients were analyzed in this
cross-sectional study. There were 362 men and 294 women. Their mean
age was 61.2 years (18 to 93). All scans had been performed for
reasons other than hip disease. Digital circumferential analysis
allowed continuous determination of the alpha angle around the entire
head-neck junction. All statistical tests were conducted two-sided;
a p-value < 0.05 was considered statistically significant.Aims
Methods
The aim of this study was to analyse the gait
pattern, muscle force and functional outcome of patients who had undergone
replacement of the proximal tibia for tumour and alloplastic reconstruction
of the extensor mechanism using the patellar-loop technique. Between February 1998 and December 2009, we carried out wide
local excision of a primary sarcoma of the proximal tibia, proximal
tibial replacement and reconstruction of the extensor mechanism
using the patellar-loop technique in 18 patients. Of these, nine
were available for evaluation after a mean of 11.6 years (0.5 to
21.6). The strength of the knee extensors was measured using an
Isobex machine and gait analysis was undertaken in our gait assessment
laboratory. Functional outcome was assessed using the American Knee
Society (AKS) and Musculoskeletal Tumor Society (MSTS) scores. The gait pattern of the patients differed in ground contact time,
flexion heel strike, maximal flexion loading response and total
sagittal plane excursion. The mean maximum active flexion was 91°
(30° to 110°). The overall mean extensor lag was 1° (0° to 5°).
The mean extensor muscle strength was 25.8% (8.3% to 90.3%) of that
in the non-operated leg (p <
0.001). The mean functional scores
were 68.7% (43.4% to 83.3%) (MSTS) and 71.1 (30 to 90) (AKS functional
score). In summary, the results show that reconstruction of the extensor
mechanism using this technique gives good biomechanical and functional
results. The patients’ gait pattern is close to normal, except for
a somewhat stiff knee gait pattern. The strength of the extensor
mechanism is reduced, but sufficient for walking. Cite this article:
