Non arthritic hip pain is a common problem, which can at times be disabling. Commonly it affects the young, but there are conditions like infections, tumours and inflammations that can happen in any age group.
Non arthritic hip pain can be classified as follows:
A. Intra-articular: originating from joint itself
B. Extra-articular: pain originating from outside the hip joint
The intra-articular hip pain is usually due to chondrolabral lesions or labral tears. Please note that degenerative labral tears can be asymtomatic in patients in their fifth decade and beyond. Labral tears which are symptomatic are almost always due to a pathology in the hip. It is usually the chondral lesion adjacent to the labral tear that is symptomatic.
The causes of labral tears (and chondrolabral) lesions are
- Femoral head deformity
- Acetabular dysplasia
- Femoro-Acetabular Impingement
- Ligament Laxity
- Loose bodies
- Bio mechanical overloading
- Excessive retroversion or anteversion
- Incongruent hip
1. Femoral head deformities
Old healed Slipped Upper Femoral Epiphysis and Perthes disease cause asphericity of the femoral head. This causes a cam deformity. This deformity can be subtle or more obvious. Sometimes CT scan and MRI scan helps. Treatment involves femoral osteotomies, hip arthroscopy, or Acetabular osteotomy.
2. Acetabular dysplasia
These are missed late presenters of DDH. Patients are young adults, who get pain because of instability. The labrum is often hypertrophied and torn or avulsed when they present. Special X-rays are needed. Treatment involves periacetabular osteotomy, a technically demanding procedure.
3. Femoral-Acetabular Impingement
This is a subtle mismatch in the sphericity of the femoral head and acetabulum. This gives rise to chondrolabral lesions. The Cam impingement is due to femoral head deformity, often seen in men. Pincer impingement is due to over coverage of acetabulum, often seen in women. More commonly there is a combination of both. Investigations: X-rays and MRI arthrogram. Treatment is by arthroscopy or open operation.
4. Ligament Laxity
This leads to increased excursion of the femoral head which edge loads the acetabulum and causes labral tears. Often happens in young girls who are ballet dancers and gymnasts. This causes anterior hip capsule insufficiency.Treatment is physiotherapy and sports rehabilitation.
5. Loose bodies
Intra-articular loose bodies can cause third body wear, chondral and chondrolabral lesions. They can cause locking and restriction in range of movement. Synovial osteochondromatosis is a condition that can produce hundreds of osteocartilagenous loose bodies that originate from synovial metaplasia. It usually affects only one joint.
Fracture dislocation of the hip, osteochondritis dissecans are other causes. Osteochondritis dissecans gives rise to osteochondral loose bodies from the joint surface due to localised vascular insult to the femoral head. They can also be post traumatic. Investigations are X-rays, CT scan, and sometimes MRI scan. Treatment is arthroscopic removal.
6. Biomechanical overloading
Certain sports can cause edge loading or excessive forces across the hip to produce chondrolabral lesions. Therefore sports that involve excessive range of movements or twists can produce these lesions. Therefore gymnasts, ballet dancers, ice hockey players, and martial arts sportsmen are susceptible to these. Often they have certain underlying cause like cam deformity or over coverage of the acetabulum. MRI arthrogram is a special investigation for these. Treatment involves physiotherapy and hip arthroscopy.
7. Excessive retroversion and anteversion
This is the transverse plane twist in the femur and the acetabulum. The sum of twist beyond the anatomical range in the hip can cause chondrolabral lesions. This problem also can cause patellofemoral knee pain. Special summated CT scan to measure the torsion in the femur, acetabulum and tibia is needed. Treatment can involve femoral derotation, periacetabular or tibial derotation osteotomy.
8. Incongruent hip
When the surfaces of femoral head and the acetabulum do not match, then in the early stages one can get chondrolabral lesions. Stulberg, an orthopaedic surgeon in a 40 year follow up study has shown that these patients have early onset osteoarthritis. Femoroacetabular impingement is a type of a incongruent hip. Therefore there is evidence that correction of this is important. CT scan is the investigation of choice. Treatment involves arthroscopy, and or open hip procedures.
Fracture dislocations can cause severe damage to the joint surface and labrum. Osteochondral fractures, loose bodies and in severe cases acetabular fractures are a problem. CT scan is needed to plan treatment. Arthroscopy or open hip procedure is needed to treat these conditions.
Following are the causes of extra-articular hip pain.
- Sciatica; L1-L2 disc degeneration
- Meralgia parasthetica
- Snapping tendons
- Traumatic avulsion fractures
- Seronegative arthropathy
- Piriformis syndrome
1. Nerve compression from the back can cause referred pain in the hip or groin. L1-L2 disc degeneration, typically can cause groin pain. Foraminal stenosis, lumbar canal stenosis are other causes. Nerve root injections help in some cases.
2. Meralgia parasthetica is the entrapment of the lateral cutaneous nerve of the thigh under the inguinal ligament. It causes burning pain around the lateral aspect of the hip and thigh. Cortisone injection helps in these case. Rarely operative release is needed.
Inguinal and femoral hernias can cause groin discomfort and pain.
Sports hernias are actually muscle strain, tears or tendonitis around the abdominal and adductor muscles attached to the pubis. Also called athletic pubalgia, this condition happens in sports that involves twisting of the hip with force. Treatment is Physiotherapy, analgesics and on rare occasions surgery.
Adductor tendonitis can be a cause of groin pain. Physiotherapy or cortisone injection is helpful.
Around the hip, one can get bursae around the greater trochanter, sub iliopsoas, ischial tuberosity. Greater trochanter bursitis can be treated by cortisone injections, and physiotherapy.
6. Snapping tendons
Iliotibial band snaps around the greater trochanter and iliopsoas snaps around the anterior hip capsule. The iliotibial band snapping can appear as pseudosubluxation of the hip. Physiotherapy is the main treatment. Arthroscopic release is possible.
7. Traumatic avulsion fractures
One can get avulsion fractures of anterior inferior iliac spine (rectus femoris), lesser trochanter (iliopsoas), greater trochanter(gluteus medius), hamstring, and adductor longus. Treatment is conservative, rarely arthroscopic or open repair is needed.
8. Seronegative arthropathy
Inflammatory arthropathy can cause myalgia and extrarticular pain. Treatment is by a rheumatologist.
9. Piriformis syndrome.
The pisiform is tendon can irritate the sciatic nerve and can cause buttock pain and radiating pain around the back of the thigh. Physiotherapy helps.
Note: Infections and tumours can cause pain around the hip.
Examination of the hip:
- Gait: look for limp
- Range of motion
- Palpation of tender areas
- Special tests: Trendelenburg, impingement tests
- Limb length discrepancy