1. Why is the hip joint so stable?
It is a multiaxial ball-and-socket joint that is comprised of two structures. Specifically, the femoral head and the acetabulum. The femoral head forms approximately two-thirds of a sphere and inserts into the acetabulum. Surrounding the lip of the acetabulum is a fibrocartilaginous structure called a labrum. This labrum deepens the acetabulum, thus increasing stability. Surrounding the ball and socket joint is a capsule that also increases stability. Also, within the hip joint a negative pressure exists which contributes to the stability of the hip joint. Muscles play less of a role in providing joint stability at the hip than they do at other joints.
2. What is the price of this joint stability?
The hip joint has a high degree of stability at the expense of some movement. In contrast, the glenohumeral joint has greater freedom of movement but less stability.
3. What are the named ligaments of the capsule of the hip joint?
The three named ligaments (or thickenings) of the capsule are the iliofemoral (Y-ligament of Bigelow), which is considered the strongest ligament in the body, the ischiofemoral, and the pubofemoral ligaments.
4. In which direction is the hip most likely to dislocate?
In the total hip patient, the most common direction for dislocation is posterior. The incidence of dislocation of the posterior is 2 – 3%. The patient typically presents in severe pain with the hip flexed, internally rotated, and slightly adducted. The patient in which a total hip replacement is not performed, posterior is still the most common direction for dislocation. The traumatic dislocation is most commonly associated with an acetabular fracture and is associated with sciatic nerve injury of 8–20%. Evaluation should include testing of toe and ankle movement and sensory exam of the foot.
5. What about anterior dislocations?
Anterior dislocations are fairly uncommon, but when they do present, the patient will have a fixed abducted, flexed, and externally rotated extremity. They are also associated with sciatic nerve injury, as well as possibly femoral nerve injury.
6. What is the innervation and blood supply to the hip joint? Why is this clinically important?
The hip joint is supplied by multiple nerves, including the femoral nerve, obturator nerve, superior gluteal nerve, and the nerve to the quadratus femoris. Pain in the true hip joint frequently refers to the groin and other sensory distributions of these nerves. Blood supply to the head of the femur comes from the branch of the obturator artery that passes through the ligament of the head of the femur as well as from multiple branches that pierce the capsule, originating from the femoral circumflex arteries, superior gluteal artery, and obturator artery. These arteries are often damaged during fracture, making healing difficult.
7. What is the most common site of osteonecrosis?
The femoral head. However, the humeral head and distal femur are involved in 10–15% of cases.
8. What is hip dysplasia?
Hip dysplasia is a comprehensive term that has been used to describe the failure of the femoral head or the acetabulum to develop properly. There are a number of pediatric conditions that result in the development of acetabulum or the femoral head. Some include congenital hip dislocation, Perthes, and possible femoral focal deficiency.
9. What is Legg-Calvé-Perthes disease?
Avascular necrosis of the femoral head. It usually occurs in children aged 5–12 years and may be due to interruption of the vascular supply of the hip leading to ischemic necrosis.
10. What are common causes of a "snapping hip"?
There are two forms of snapping hip. One is a consequence of the gluteal portion of the iliotibial band snapping over the greater trochanter with internal rotation of the femur. The second form of snapping hip is when the iliopsoas tendon snaps over the femoral head/anterior capsule when the hip is flexed and externally rotated. The most common cause of snapping hip is overuse, as well as trauma to the area. Often times, the snapping hip is associated with the iliopsoas tendon popping over the hip capsule, resulting in an audible pop that can be heard by others in the room.
11. What is SCFE or "hip slip"?
A slipped capital femoral epiphysis is when the epiphysis falls off the femoral neck. A simple description is the ice cream falls off the cone. Typically, it is associated with significant growth spurts and in children who are considered overweight. It is more common in males than in females. The onset is often associated with a painful limp or difficulty with weight-bearing. Radiographs include an AP of the affected extremity, as well as a true lateral. A "frog-leg" lateral x-ray should not be taken in this child in that it may cause further displacement of the epiphysis on the femoral neck.
12. Name the most common cause of a painful hip in children under 10 years of age.
Acute transient synovitis, which is usually nonspecific and self-limited.
13. What is an intertrochanteric fracture?
An intertrochanteric fracture occurs between the greater and lesser trochanters along the intertrochanteric line and outside the hip joint capsule. Treatment of choice is a sliding hip screw.
14. What is meralgia paresthetica and how does it present? What are some causes?
Compression of the lateral femoral cutaneous nerve causing numbness in the anterolateral thigh is called meralgia paresthetica. Patients often complain of burning, pain, and hypoesthesia in the anterolateral thigh. Causes included nerve entrapment, surgical injury, blunt trauma, or external pressure such as belts or other clothing.
15. What causes of osteoarthritis in the hip may lead to a THA?
Idiopathic primary osteoarthritis
Developmental dysplasia of the hip
Slipped capital femoral epiphysis
Osteonecrosis (avascular necrosis [AVN])
History of trauma leading to joint incongruity
Other inflammatory arthritides
16. Where are the most frequent sites of hip fracture in the elderly?
Femoral neck and the intertrochanteric and subtrochanteric areas.
17. What are the most common known associated factors of avascular necrosis of the hip in adults?
Steroid use and alcohol use account for about 90% of known associated factors of avascular necrosis in the patient population under age 45 years. Other conditions associated with osteonecrosis include myeloproliferative disorders, Gaucher disease, trauma, chronic pancreatitis, Caisson disease, sickle cell and other anemias, and radiation.
18. What is the incidence of bilaterality for osteonecrosis?
Literature shows there is an 80% risk of bilateral involvement. One side may be entirely asymptomatic.
19. What are the different methods of evaluating osteonecrosis of the femoral head?
Adequate anteroposterior (AP) and lateral radiographs are the first step. Magnetic resonance imaging (MRI) is the most sensitive and specific modality. Computed tomography (CT) scan can be used to assess femoral head collapse. Invasive modalities include direct pressure measurements, venography, and biopsy. Note: Technetium scans have recently been shown to be less sensitive and specific.
20. Why and how is the Thomas test performed?
The Thomas test is performed to assess flexion contracture of the hip. The patient lies supine on the examining table. To test the right hip, the left hip and knee are maximally flexed. A positive result or (flexion contracture) is present if the right thigh elevates above the table passively. If the right thigh is pushed down to the table and excessive passive lordosis of the spine occurs, this is also positive.
21. What is the FABER test?
FABER stands for flexion, abduction, external rotation. This nonspecific test (also known as the Patrick test) helps detect pathology in the hip and sacroiliac (SI) joint. The patient is in the supine position and the foot of the tested side is placed on the knee of the opposite side. The tested hip is then lowered to a flexed, abducted, and externally rotated position (the "frog leg" position). Inguinal pain is suggestive of hip pathology. Increased pain elicited by increasing the ROM by placing pressure on the opposite anterior superior iliac spine suggests SI joint pathology.
22. Why and how is the Ober test performed?
The Ober test is used to evaluate contracture of the tensor fasciae latae (TFL) and iliotibial band. The patient lies on his or her side with the lower leg flexed at the hip and knee for stability. The examiner flexes and abducts then extends the patient's upper leg with the knee flexed to 90°. The examiner then releases the upper leg. If a contracture is present, the upper leg will remain abducted and will not fall to the table.
23. What changes in the physical exam are noted in hip osteoarthritis?
The typical first sign is loss of internal rotation, followed by loss of flexion and extension, and eventually contracture. An antalgic gait and abductor lurch (swaying of the trunk over the side of the affected hip) also may be noted.
24. What is the Garden classification of fractures?
Garden Classification of Femoral Neck Fractures
||Incomplete or impacted fracture
||Trabeculae of the inferior neck are still intact
||Complete fracture without displacement
||Fracture lines across entire femoral neck
||Slight varus deformity
||Complete fracture with partial displacement
||Needs a reduction
||Shortening and external rotation of distal fragment often occurs
||Incomplete displacement between femoral fragments
||Complete fractured with total displacement
||No continuity between proximal and distal fragments
||Acetabulum and the femoral head are alignedAdapted from Wheeless CR:
||Wheeless' Textbook of Orthopaedics. 1996.
25. Why should a patient with unilateral hip osteoarthritis carry a cane on the unaffected side?
A patient with unilateral hip osteoarthritis should carry a cane on the unaffected side because it essentially moves the lever arm away from the affected joint, thus reducing the amount of work necessary for the abductors of the affected side, allowing the patient to maintain a level pelvis.
26. Discuss the symptoms and treatment of trochanteric bursitis.
Classic symptoms include gradual onset pain in the bursa region, pain upon arising in the morning, aggravation of pain during ambulation, and an antalgic gait. Pain can radiate down the lateral aspect of the leg and into the buttock. Thus, the syndrome is sometimes confused with sciatica. Physical exam will reveal point tenderness over the greater trochanter, which can be exacerbated by external rotation and abduction of the hip. Conservative treatment includes anti-inflammatories and an iliotibial band stretching program. Injection of local anesthetic and corticosteroids into the bursa may relieve symptoms.
27. What are treatment options for femoral neck fractures?
Treatment for femoral neck fractures is dependent upon age, as well as fracture displacement. With treatment to the young patient with a displaced fracture, attempts should be made to reduce the fracture and to provide internal fixation. For the older patient a displaced fracture has a high rate of non-union and therefore should be treated with a unipolar or bipolar endoprosthesis of even a total hip replacement.
28. What are some significant complications after total hip replacement and how often do they occur?
Significant complications associated with total hip replacement may include nerve damage at a rate of .5 to 4%, infection which occurs at a rate of .5 to 3%, DVT which occurs at a rate of 4 to 20%, and a pulmonary embolism which occurs at a rate of .04 to 2%. Other complications include heterotopic bone formation, leg length inequality, and continued pain.
29. How does loosening of the hip prosthesis present? How is it usually detected?
Loosening of a hip prosthesis often presents insidiously. The patient may have groin pain or thigh pain depending on whether or not it is the acetabular component or the femoral component becoming loose. Loosening is detected by the comparison of new films to old films. Radiolucency around the prothesis or migration of the prosthesis is suggestive of loosening.
30. For a patient requiring ipsilateral hip and knee replacements, in which order should the surgeon proceed?
Patients who have ipsilateral hip and knee arthritis should undergo a hip replacement first. The concern is that with inadequate hip motions secondary to the arthritis the patient would be unable to undergo adequate knee replacement if they underwent a knee replacement first.
31. What is an osteotomy?
A hip osteotomy is a surgical procedure in which the bones of the hip joint are cut, reoriented, and fixed in a new position. Healthy cartilage is placed in the weight-bearing area of the joint, followed by reconstruction of the joint in a more normal position.
32. How does an intertrochantric osteotomy affect the leg length?
Open valgus osteotomy generally lengthens the limb; varus osteotomy usually shortens the limb.
33. Who is the ideal patient for hip arthrodesis?
Young adults or older adolescents with end-stage arthritis who are engaged in heavy labor are the ideal type of patients for a hip arthrodesis.
34. What are the indications for hip arthroscopy?
- Removal of loose bodies
- Repair of torn labrum
- Synovitis (the synovial lining of the hip joint is inflamed causing disabling pain that may be relieved by a synovectomy)
- Palliative treatment to buy time for a future hip arthroplasty
35. What is the difference between total hip arthroplasty (THA) and hemiarthroplasty?
In a total hip arthroplasty and a hemiarthroplasty the femoral head and neck are resected and replaced with a prosthesis. In a total hip replacement the acetabulum is also resurfaced and an acetabular component is inserted. In a total hip replacement the bearing surface is metal-on-plastic, metal-on-metal, or ceramic-on-ceramic. In a hemiarthroplasty the bearing surface is metal-on-acetabular cartilage.
36. What are the indications for total hip arthroplasty?
The goal of hip arthroplasty is to relieve pain, correct deformity, and restore range of motion (ROM) and function. Indications include severe degenerative changes and failure of nonoperative treatment for 3–6 months. Occasionally, THA is chosen when a fracture of the femoral head or neck cannot be repaired or repair has little chance for clinical success (e.g., an 80-year-old with a severely displaced femoral neck fracture).
37. What is metal on metal hip resurfacing?
Hip resurfacing is a surgical alternative to conventional hip arthroplasty. The femoral head is reshaped to accept a metal cap with a small guide stem. The head size is about 50 millimeters in diameter and a metal cup is set into the acetabulum.
38. Are there any advantages with the use of metal on metal resurfacing devices?
- Femoral head is preserved.
- Femoral canal is preserved and no associated femoral bone loss with future revision.
- Larger size of implant "ball" reduces the risk of dislocation significantly.
- Stress is transferred in a natural way along the femoral canal and through the head and neck of the femur. With the standard THR, some patients experience thigh pain as the bone has to respond and reform to less natural stress loading.
- Use of metal rather than plastic may reduce osteolysis and associated early loosening risk.
39. Are there any disadvantages with the use of metal on metal devices?
- Lack of long-term follow up. Current device has only been used for about 7 years.
- Despite known low wear rate, longevity and long term effects of wear debris are unknown.
- For some surgeons, the procedure has a longer surgical time.
- The procedure requires somewhat more skill of surgeon (learning curve)
40. What are the different bearing surfaces available for total hip arthroplasties?
- Metal-on-metal (cobalt-chrome alloy)
41. What are the recently publicized concerns with ceramic-on-ceramic fractures?
Recent use of ceramic-on-ceramic have led to very low fracture rates where the reported risk is 0.015 percent which should not be a concern. Ninety percent of fractures occur within 36 months of implantation.
42. What are the recently publicized concerns about metal ions toxicity?
Metal ions have been found to be increased in patients with metal-on-metal prostheses, but these increases have been maintained over six to seven year follow-up and have not caused a problem. There have been no reports of adverse toxic effects of these metal-on-metal devices at this point, so this still should be known, but represents a minor concern.
43. Are there any advantages with the use of the so called "large femoral heads"?
Large femoral heads may have advantages of reducing dislocation rates, improving range of motion and reducing wear. Various companies have developed these large femoral heads, mostly with metal-on-metal devices, although even various other metal-on-plastic or ceramic-on-ceramic have larger heads that have been previously used.
44. What are minimally invasive approaches to the hip?
Minimally invasive approaches to the hip involve less tissue disruption through smaller skin incisions. There are two incision approaches and just small posterolateral or small anterolateral. Most studies have shown no difference in outcome and some studies have shown increased complication rates. It is still being studied and certainly the field has led to smaller incisions, but at this point there may be no advantage except for a cosmetic one with a small incision.
45. Define weight bearing.
Body weight supported through the affected limb is measured by placing the limb on a weight scale and applying force on the scale.
||0% of body weight
|Toe-touch weight bearing
||Up to 20% of body weight
|Partial weight bearing
||20–50% of body weight
|Weight bearing as tolerated
||50–100% of body weight
|Full weight bearing
||100% of body weight
46. How does mode of fixation affect rehabilitation?
Patients with cemented prostheses are capable of bearing full weight immediately after surgery because the cement reaches 90% of its strength 10–15 minutes after mixing. Within 24 hours this cement is at maximum strength. With a porous ingrowth prosthesis the predominant method of rehabilitation is partial weight bearing for a period of 6 weeks followed by full weight bearing. There is recent literature that suggests that you can full weight bear with a porous ingrowth prosthesis without an increased risk of ingrowth failure.
47. Why should physiatrists be aware of the surgical approach used in a hip arthroplasty?
Because muscle groups should be targeted according to approach. The lateral approach involves splitting the hip abductors (gluteus medius and minimus) with repair back to the greater trochanter or trochanteric osteotomy with repair of the osteotomy. The hip abductors should be a target of strengthening. The posterior approach involves splitting the gluteus maximus and releasing the short external rotators, which are repaired. The hip extenders and the short external rotators are targeted.
48. How long will patients have significant pain after hip surgery?
Arthritis pain is typically eliminated immediately. Surgical pain can last 2–3 weeks. Pain may be elicited by activities and ambulation for several months depending on various factors, such as preoperative deformity and degree of muscle atrophy. It may take months to rebuild muscle mass and strength to reduce activity-related pain.
49. Can patients return to playing sports after hip replacement surgery?
Most patients can return to low-impact sports (e.g., golf, doubles tennis, bowling, walking, and using exercise machines). High-impact exercises (running, singles tennis, basketball, volleyball, and football) should be avoided, because they may lead to excessive wear of the prosthesis.
50. When will the patient receive full benefit after hip arthroplasty?
Typically by 3 months, the patient will have regained most of his or her strength across the joint and ROM. By 1 year, the patient usually will have achieved full benefit from the operation.
51. Describe a general management approach in a patient with total hip arthroplasty.
|Day of surgery
||Deep breathing exercises, incentive spirometry, active ankle ROM exercises
|Postop day 1
||Quadriceps isometric exercises, gluteus muscle isometrics (depending on surgical approach), maintain hips in abduction, active assisted and knee flexion exercises as tolerated
|Postop day 2–6
||Begin ambulation with a walker or crutches, progressive gait training, begin reconditioning exercises to unaffected limbs; transfers to the unaffected side
||Add light resistance exercises; hip flexor stretches; emphasize transfers – and begin on affected side
||Toe-touch weight bearing for 6 wks; advance to weight bearing as tolerated
||If secure reattachment, start WBAT; if tenuous, partial weight bearing
||Instruct on hip precautions, energy conservation, and work simplification techniques
||Active assisted exercise; progress to active ROM motion and strengthening exercises
||Teach adaptive ADLs
|Postop 7–3 months
||Progressive strengthening and ranging of the trunk, hip, and knee
||Closed kinetic chain exercises
||Improve endurance and gait pattern
||Eliminate the use of assistive devices
||Pool therapy, bicycling, long-distance walking, progressive stair climbing, and isotonic exercises with weights are encouraged
|Postop month 3
||Focus on level and location of pain, daily walking distance, sitting or stand- ing duration, use of assistive devices, stair climbing method, analgesics, and community reintegration
|ROM = range of motion; WBAT = weight bearing as tolerated; ADLs = activities of daily living.
52. How long should a patient maintain total hip precautions?
10 to 12 weeks. This allows for a pseudocapsule to form and soft tissue to heal. Incidence of dislocation is reduced by greater than 95% after 12 weeks. The use of an anterior approach to the hip may further reduce the incidence of dislocation.
53. How should a patient negotiate stairs after hip surgery?
"Up with the good and down with the bad." When going up stairs, the patient should lead with the nonoperative extremity and follow with crutches and operative extremity. When descending, he or she should lead with crutches and the operative extremity and follow with the nonoperative extremity.
54. What are the most common causes of falls after hip surgery?
Decreased visual acuity and balance sensation in the elderly population. Accident prevention tips should be stressed. An in-home visit for safety should be considered. Throw rugs, thick carpets, and poor lighting may cause stumbling and should be avoided. All rooms must be well-lit. The path from the bed to the bathroom is especially important, because many falls occur when trying to get to the bathroom at night.
55. Do patients need prophylaxis for deep venous thrombosis (DVT) after hip replacement?
The incidence of DVT after hip surgery is greater than 50% in most reports. It is standard to give some form of prophylaxis, which can include mechanical adjuncts such as support hose and pneumatic compression devices, and should be continued throughout hospitalization. Pharmacologic prophylaxis includes warfarin, heparin, and aspirin.
56. Why should abduction pillows be utilized? When? For how long?
An abduction pillow prevents dislocation of the hip prosthesis (adduction, internal rotation) while the patient is sleeping or resting in bed. It is used for the first 6–12 weeks.
57. What is the sequence of ambulatory aids usually given to patients after THA?
Parallel bars (days 1–2), crutches or a walker (first 6 weeks), and one crutch or cane (next 6 weeks). Greater than 70% of patients are ambulatory without an assistive device at the end of 3 months.
58. Give four goals of occupational therapy after THA.
- Reestablish basic activities of daily living (ADLs) with modifications that keep the patient's ROM within the restricted limits.
- Teach joint protection.
- Review fall risks.
- Provide equipment with training.
59. Are resisted concentric exercises important after hip or knee surgery?
For the first 6–8 weeks, the patient can perform isometrics and active ROM exercises against gravity. Concentric exercises against resistance should be avoided. After 6–8 weeks, resisted open kinetic chain strengthening with 1–10 lbs. can begin. Heavier weights cause undue wear on the prosthetic components.
60. How do you assess flexion contracture of the hip?
The Thomas test. The patient tries to lower the extremity flat on the examination table, while holding the opposite thigh against the abdomen. The test is positive if the hip does not extend fully.
61. What are the surgical indications and rehabilitations for the various hip fracture types?
Surgical Procedures and Rehabilitation for Hip Fractures
|Fractures and Type
|Displaced fracture (Garden III and IV)
||Hemiarthroplasty; ORIF (in younger patients)
|Undisplaced and impacted fractures (Garden I and II)
||Depends on the stability of surgical fixation
|Undisplaced, displaced two-part fractures, or unstable three-part fractures
||Treated operatively with multiple pins or screws and side-plate devices
||Depends on degree of fracture stabilization, bone stock, patient's frailty, and risks of immobility. Most patients are WBAT
|Simple, fragmented, or comminuted
||ORIF with a blade plate and screws or an intramedullary nail
||Delayed until fracture demonstrates evidence of healing
|ORIF = open reduction and internal fixation; WBAT= weight-bearing as tolerated.
62. What are the negative predictors of ambulation after hip fracture?
Lack of social support, lower-limb contractures, age over 85, and poor prefracture functional status. Generally, a patient will lose one level of function after a hip fracture. Inability to transfer or ambulate, incontinence, dementia, fewer hours of physical therapy, and lack of family involvement may require institutionalization.
63. What are the major post-operative complications following THA that the Physiatrist must be aware of during a rehabilitation program?
DVT (and PE), deep infection, and dislocation. The risk of all of these increases with a surgical revision compared to primary THA. Other complications include GI (paralytic ileus), urinary retention, and neuropathy.
64. What nerves may be damaged during THA surgery?
The sciatic nerve is most often involved. The Peroneal fibers tend to be more affected due to their relative outer location within the nerve. Femoral neuropathies can also occur.
65. When can patients begin to drive?
For a right THA, patients can usually begin to drive after 4-6 weeks. After left THA – 1 week is usually enough. However, total hip precautions must be maintained.
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Authored by :Michael A. Mont, M.D., German A. Marulanda, M.D., Ronald E. Delanois, M.D., Thorsten M. Seyler, M.D., Andrew Haig, M.D., Howard Choi M.D., and Alan Friedman, M.D.
(Reprinted by permission from Physical Medicine and Rehabilitation Secrets 3'd Edition:O'Young,BJ,Young,MA,Stiens,SA (eds.)