Background: Patients who have had a hip
arthrodesis have been reported to have pain in the back and the
knee due to an altered gait. There is little information about the
specific compensatory mechanisms that are adopted when walking.
The purpose of this study was to objectively define gait adaptations
after an arthrodesis of the hip and to correlate the kinematic findings
with pain and other patient outcomes.
Methods: Nine patients who had had an arthrodesis
of the hip at an average age of thirteen years and five months (range,
ten years and nine months to sixteen years and eleven months) were
evaluated with gait analysis and muscle strength-testing and completed
a questionnaire related to pain and function. The average duration
of follow-up was eight years and ten months (range, two years and
one month to thirteen years and ten months). The frequency of the
postoperative visits varied. Seven patients were adults at the time
of the study and were called back specifically for the study.
Results: All patients had decreased cadence
and step lengths. The kinematic findings included decreased dorsiflexion
of the ipsilateral ankle, hyperextension of the ipsilateral knee
during the stance phase, and a tendency toward increased genu valgum
during gait. In normal gait, there is no genu varum or valgum during
the stance phase.
The patients had an average (and standard deviation) of 7 ± 4
degrees of genu valgum. Pelvic and lumbar motion in the sagittal
plane was excessive in all patients. Strength-testing revealed clinically relevant
weakness in the ipsilateral quadriceps in all patients, with a difference
of more than 20 percent between the two extremities in six patients. The
gastrocnemius-soleus muscle was stronger on the side with the fused
hip in six patients.
The questionnaire, designed by Harris in 1969 and completed by
the patients at the time of the gait analysis, revealed back pain
in seven patients. The questionnaire was administered only once.
The functional outcome as measured with use of the same questionnaire
worsened as the duration of follow-up increased.
Conclusions: The gait analysis showed excessive
motion in the lumbar spine and the ipsilateral knee in all nine
patients. This abnormal motion led to pain as the duration of follow-up
increased, and all patients who had been followed for four or more
years after the arthrodesis complained of back pain. We hypothesized
that excessive motion for an extended duration can lead to back
pain. The preferred position of the hip for the arthrodesis was
20 to 25 degrees of flexion, neutral abduction-adduction, and neutral