Hip Osteoarthritis
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Direct answer
Hip osteoarthritis is a degenerative disease of the hip joint marked by cartilage loss, subchondral sclerosis, osteophytes and cysts, and it is graded radiographically by the Kellgren-Lawrence system. Typical symptoms are groin or buttock pain and morning stiffness, and narrowing of the superior joint space marks loss of load-bearing cartilage. Conservative care comes first, and arthroplasty is offered when pain and disability persist despite it.
What you must remember
- Kellgren-Lawrence grade: 0 is normal, 1 doubtful, 2 minimal osteophytes with possible narrowing, 3 moderate osteophytes with definite narrowing and sclerosis, and 4 large osteophytes with severe narrowing and deformity.
- Superior joint space: narrowing is typically superior (superolateral) in the hip, reflecting loss of weight-bearing cartilage, unlike the medial narrowing seen in the knee; concentric axial narrowing points instead to inflammatory arthritis.
- Subchondral changes: sclerosis, cysts and osteophytes at the femoral head and acetabular rim are the hallmark radiographic features.
- Primary versus secondary: most cases are primary, while developmental dysplasia, Perthes sequelae, slipped capital femoral epiphysis and femoroacetabular impingement cause earlier secondary disease.
- Trendelenburg gait: abductor weakness from pain and disuse produces a limp, and a positive Trendelenburg sign is a common clinical finding.
- Conservative care: education, weight reduction, exercise, walking aids and simple analgesia, with an intra-articular corticosteroid injection as temporary relief.
- Surgical threshold: arthroplasty is offered for disabling pain and loss of function persisting despite conservative care, with imaging that matches the symptoms.
Staging the pathway before arthroplasty
A 62-year-old retired teacher has three years of groin pain, short walking distances and morning stiffness, with a moderate joint space loss on radiographs. The pathway moves from diagnosis to surgery only after conservative measures have been tried.
- Confirm the diagnosis: groin or buttock pain, start-up stiffness and reduced internal rotation, with radiographs showing narrowing, osteophytes and subchondral sclerosis.
- Grade the disease: Kellgren-Lawrence grading standardises the report, though symptoms guide the decision more than the grade alone.
- Look for a secondary cause: dysplasia, Perthes sequelae, slipped epiphysis or impingement in a younger patient may shift the choice towards osteotomy.
- Educate and modify: load management, weight reduction and low-impact exercise such as cycling and swimming reduce symptoms.
- Strengthen and treat pain: hip abductor and core exercises with simple analgesia form the core of control, and NSAIDs need caution in older patients.
- Inject for temporary relief: an intra-articular corticosteroid injection can bridge a flare but does not alter the course of the disease.
- Refer for arthroplasty: when pain and disability persist and imaging matches the symptoms, total hip arthroplasty is discussed.
Where the exam tries to catch you
Hip osteoarthritis questions test grading, secondary causes and the timing of surgery.
- Trap: operating on a severe radiographic hip that is painless Correct: surgery follows symptoms and disability, so the radiographic grade alone does not justify arthroplasty.
- Trap: missing a secondary cause in a young adult with hip osteoarthritis Correct: dysplasia, Perthes sequelae or impingement change the choice, often towards osteotomy before any arthroplasty.
- Trap: attributing groin pain in an older patient to lumbar spondylosis alone Correct: hip disease refers pain to the groin and knee, so the hip must be examined directly.
Frequently asked questions
What are the Kellgren-Lawrence grades in hip osteoarthritis?
The Kellgren-Lawrence system grades hip osteoarthritis from grade 0, which is normal, to grade 4, which is severe. Grade 2 shows minimal osteophytes with possible narrowing, while grade 4 shows large osteophytes, marked narrowing, severe sclerosis and deformity.
Which radiographic sign is characteristic of hip osteoarthritis?
Narrowing of the superior joint space is a characteristic radiographic sign of hip osteoarthritis, reflecting loss of load-bearing cartilage. Subchondral sclerosis, cysts and osteophytes at the femoral head and acetabular rim add further support to the diagnosis.
Which conservative measures come before total hip arthroplasty?
Conservative measures for hip osteoarthritis include patient education, weight reduction, hip strengthening, walking aids and simple analgesia. An intra-articular corticosteroid injection may give temporary relief before arthroplasty is discussed for disabling disease.
Which secondary causes lead to early hip osteoarthritis?
Developmental dysplasia of the hip, sequelae of Perthes disease, slipped capital femoral epiphysis and femoroacetabular impingement all cause secondary hip osteoarthritis. These conditions often present in younger adults, and they influence whether osteotomy is considered before arthroplasty.