Exercise Therapy and Patient Education for Individuals With Hip Osteoarthritis of the Hip. A Case-Control Study
Condition: Hip Osteoarthritis
MeSH terms: Osteoarthritis; Osteoarthritis, Hip
Study type: Observational

Summary: 
      To identify differences between patients with OA of the hip in an early stage and a healthy
      control group.

      Hypothesis 1.1 There are significant differences between patients with OA of the hip in an
      early stage and a healthy control group in terms of functional capacity, biomechanical /
      kinematic variables, muscle strength and range of motion.

      Osteoarthritis (OA) is by far the most prevalent joint disorder today. The knee and the hip
      are large joints to be targeted and is an important cause of pain and disability. In knee OA,
      it is shown that significant risk factors in developing the disease are quadriceps weakness,
      joint instability, and changes in joint loading. A few studies on hip OA have shown altered
      gait pattern, which affect joint loading, and one study has shown weakness in abductors,
      adductors and flexors around the hip. As joint loading and muscle weakness are important
      factors in the development in knee OA, it might as well be factors influencing OA in the hip.
      The purpose of this case-control studies was to compare hip OA patients to a healthy control
      group regarding biomechanical and clinical differences. Patients with hip pain, activity
      limitations (Harris Hip Score 60-95 p) and radiographically verified hip OA was included. The
      healthy control group will have a Harris Hip Score of 100 p. One hundred and ten patients and
      fifty controls will be asked to fill in questionnaires on pain, stiffness and physical
      function (WOMAC), quality-of-life (SF-36 v2), self-efficacy (Lorigue), and activity (PASE) in
      addition to perform 6-minute walk test, sub-maximal cardiovascular function, strength, and
      hip range of motion tests. Additionally, Qualisys Pro reflex 3D motion analysis system will
      be used during walking, one-leg standing, and raising from a chair on a sub-group of 40
      patients and 20 controls.
    

Detailed description: 
      Aim 1 To identify differences between patients with OA of the hip in an early stage and a
      healthy control group.

      Hypothesis 1.1 There are significant differences between patients with OA of the hip in an
      early stage and a healthy control group in terms of functional capacity, biomechanical /
      kinematic variables, muscle strength and range of motion.

      Material and methods.

      Design. A case-control study

      Inclusion / exclusion criteria. Twenty-five patients diagnosed with unilateral or bilateral
      OA of the hip will be recruited from the Norwegian Sport Medicine Centre, Diakonhjemmet and
      from the Orthopaedic Centre, Ullevål University Hospital, Oslo, Norway. PPatients will also
      be recruited through ads in newspaper and brief information in national tv. Radiographiccally
      verified OA of the hip will be in accordance with Danielsson's criteria for minimal joint
      space. Patients will be excluded if they have a history of resent trauma or functional
      impairment to the lower limbs or diseases which might interfere with participation.

      Control subjects will have no health problems and no injuries or functional impairment to the
      lower limbs and will be matched to the patients with OA of the hip by age and gender.

      Outcome measures.

      Background descriptive data, including anthropometrical (age, gender, height, weight) and
      sociodemographic information (marital status, social support, leisure time, sick-leave,
      physical activity, occupational background, co-morbidity, hip pain history, former treatment
      for hip pain / OA), and consumption of analgetics will be collected by questionnaire at
      inclusion. Outcome measures will cover all functional levels defined by the World Health
      Organization's (WHO) International Classification of Functioning, Disability, and Health
      (2002) and will include:

      Pain and activity limitation: Hip pain will be assessed by a horizontal visual analogue scale
      (VAS) (0-100 mm; 0 represents "no pain" and 100 represents "as much pain he/she can possibly
      imagine") (Revill et al. 1976). Both self-reported and observed functional capacity will be
      evaluated. Self-reported functional capacity will be registered by the disease-specific
      questionnaire Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) (Bellamy
      et al. 1988). Observed functional capacity will be assessed by the 6 minute walking test
      (Enright, 2003), where the patient is instructed to walk as quickly/fast as possible forth
      and back on a 20 m course, and by the subaximal bikecycle test (Astrand, 1986) where the
      heart-rate is registered on a constant load and speed.

      Health related quality of life and pain management: Quality of life will be assessed by using
      the generic questionnaire SF-36 v.2 (Jenkinson, 1999). Self-efficacy beliefs for pain will be
      registered using the self-efficacy subscale for controlling pain developed by Lorig et al
      (Lorig et al. 1989). The scale is found to be valid and reproducible in patients with chronic
      arthritis (Lorig et al. 1989).

      Gait analysis: Kinematic data will be collected using Qualisys pro-reflex motion analysis
      system with eight cameras at a sampling frequency of 240 Hz and synchronized with two force
      platforms sampling at a rate of 960Hz (AMTI Model LG6). All markers will be present during
      standing calibration. During the dynamic trials all the anatomical markers will be removed.

      Subjects will be instructed to walk along a 17m walkway in which two force plates are
      embedded. The subjects will walk at their self-selected pace and practice trials will be
      performed until the subject could contact the force platforms with only one foot (not
      targeting) and with a constant velocity within 5% deviation. Speed will be measured by
      photoelectric beams located 3.06m apart, midway along the walkway. Experienced physical
      therapists will be responsible for patient information, instruction and data collection.

      Muscle strength: Muscle strength of hip extensors, -flexors, knee flexors and -extensors, and
      ankle flexors and extensors, in addition to ankle plantar flexion will be tested
      isokinetically according to the manufacturer's manual (Cybex 6000). Isokinetic muscle testing
      is commonly used in the literature in various patient populations (Inkster et al. 2003; Holm
      et al. 2000b; Brox et al. 1995; Lephart et al. 1993; Newton et al. 1993). The test protocol
      will consist of five repetitions at an angular velocity of 60 deg/sec at maximal performance.
      In order to prepare patients for the test, eliminate learning effects and to obtain stable
      performance, patients will be given four test-repetitions at the same speed before the main
      test. An experienced physical therapist will perform the test.

      Range of motion: Range of motion will be measured by goniometer according to standard
      procedures (Holm et al. 2000a).

      Follow up: Data will be collected at inclusion (patients and control subjects) and after the
      intervention period (patients).

      Blinding: Personnel responsible for the intervention will not be involved in data collection.

      Registration of complications, drop-outs and adherence: Complications and drop-outs will be
      registered by persons responsible for data collection. Adherence to the exercise protocol
      will be registered by the physical therapists responsible for the treatment.

      Power calculations: Lack of information from studies of comparable OA populations in the
      literature makes it difficult to make precise power calculations. Assumption of sample size
      (110 patients and 50 control subjects) is therefore based on results from former studies in
      patients with OA of the knee or mixed populations of knee- and hip patients.

      Statistical analysis: Both non-parametric and parametric statistics will be used for data
      analysis.

      Ethics: All patients and control subjects will receive written and oral information about the
      study and sign an informed consent before inclusion (enclosed). The project will be performed
      according to recommendations of the Helsinki Declaration and application will be sent to the
      Regional Committee of Medical Research Ethics in Oslo in November 2003.
    

Observational model: Case-Control
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Patients with hip osteoarthritis and mild to moderate pain. Matched controls with no hip
        pain.
      
Keywords: Hip Osteoarthritis, muscle strength, range of motion, aerobic capacity, functional capacity, health-related quality of life