Anatomy
The hip joint consists of the acetabulum and the femoral head (caput femoris). The articular surfaces are covered with a few millimetres of cartilage to reduce stress on the articular surfaces. Around the edge of the joint is a joint lip/meniscus (labrum) that stabilises the hip joint.
Cause
Repeated strain can damage first the cartilage and then the bone under the cartilage (osteoarthritis). This can also be caused by a single, severe trauma. In some cases, the osteoarthritic changes can lead to an ‘inflammation’ of the synovial membrane (synovitis), which causes fluid formation, swelling, restricted movement and pain in the hip joint. Being overweight increases the risk of developing osteoarthritis of the hip.
Symptoms
Hip osteoarthritis pain is often localised from the groin around the outer femur (trochanter) to the buttocks (the so-called ‘C-sign’). The pain is initially predominantly related to strain, but eventually rest pain and sleep disturbing pain are added. Functionally, patients experience restriction of movement, limping and reduced walking distance.
There is reduced mobility and pain in the hip joint, primarily with rotation and movement in all extreme positions. Mild degrees of osteoarthritis are often asymptomatic. In severe cases, there is rest pain.
Examination
Diagnosen stilles på røntgen, hvilket hos yngre (< 45 years) should be of the pelvis, as hip pain in this age group often has causes other than osteoarthritis. This can be supplemented with MRI or ultrasound scans, which are more suitable for diagnosing various differential diagnoses in the hip region.
General clinical examination shows reduced mobility of the hip joint in all directions.
In many cases, there is damage to the labrum, which is best seen on MRI scans. Fluid accumulation in the hip joint or in the iliopectineal bursae can be seen on ultrasound and MRI scans.
Treatment
First-line treatment for hip osteoarthritis is patient education, exercise and, if overweight, weight loss. Treatment primarily includes relief from pain-inducing activity, stretching and graduated rehabilitation within the pain threshold. Rehabilitation primarily aims to strengthen the muscles around the hip joint and maintain joint mobility. There is no treatment that can restore the damaged cartilage (and bone).
If there is swelling in the hip joint, arthritis (synovitis) can be reduced with arthritis pills (NSAIDs) or by trying to drain the synovial fluid and ultrasound-guided injection of adrenal cortex hormone into the hip joint (and possibly into the bursa on the hip joint). Pain without joint swelling is treated with paracetamol (which has fewer side effects than NSAIDs).
For severe osteoarthritic changes with pain at rest (at night), it may be necessary to replace the hip joint. There is no evidence that being active makes the osteoarthritic changes themselves worse.
Complications
Osteoarthritic changes in the weight-bearing parts of the joint often lead to the discontinuation of sports that put a lot of weight on the hip joint. Cycling and swimming are significantly less stressful for the hip joint than running.
In particular, you need to consider:
- Inflammatory arthritis (arthritis)
- Rupture of the superficial hip flexor
- Rupture of the deep hip flexor
- Outer snapping hip
- Inner snapping hip
- Fluid accumulation in the joint
- Fatigue fracture of the femoral neck
- Bursitis on the front of the hip joint
- Inguinal hernia
- Sportsman’s hernia
- Nerve entrapment
- Muscle infiltration in one of the gluteal muscles (piriformis syndrome)
