ActionsThe hip joint supports the weight of the body in both static and dynamic multi-axial movement. Movements at the hip are flexion, extension, abduction, adduction, medial rotation, lateral rotation and circumduction.
Blood supplyThe medial and lateral femoral circumflex arteries arise from the profundus femoris in the majority of cases, which in itself is a branch of the femoral artery(5). The circumflex vessels give rise to the retinacular vessels which run proximally up the neck of femur until they reach the cartilaginous border of the head to provide the blood supply to the head. It is this distal to proximal blood flow which is of clinical significance in neck of femur fractures. The obturator artery gives rise to the vessels in the ligamentum teres, however this is of little functional significance in adults. Acetabular blood supply arises from branches of the internal iliac artery to form a circumferential blood supply to the socket. The branches of the internal iliac that make up this supply are as follows; obturator artery, superior gluteal artery and inferior gluteal artery(1,6).
Nerve SupplyHiltons law describes innervation of a joint:
“the nerve supplying a joint supplies also the muscles which move the joint and the skin covering the articular insertion of those muscles”(7).Innervation of the hip joint is therefore derived from the femoral, obturator, sciatic nerve, superior gluteal and nerve to the quadratus femoris(8, 9).
DevelopmentDerived from the mesoderm. Lower limb buds appear at 28 days gestation(1). By 7 weeks an interzone or cleft forms which will form the femoral head and the acetabulum(1, 2). At 11 weeks the head is completely encircled by acetabular cartilage and by week 16 the capsule and musculature of the joint are formed(1, 2). Postnatal further development of both the acetabulum and proximal femur depends on functional use and correct location of the femoral head. In the proximal femur this notably affects the angle of the neck. At birth the acetabulum is immature and relies on the femoral head being correctly positioned and functional within the acetabulum to develop, for example in untreated development dysplasia of the hip the acetabulum is shallow and steep(1, 2). The first 8 years are of vital importance as at this age ossification centers form in the acetabulum and further remodeling is very limited; ossification centers of the acetabulum fuse between 17 and 18 years(1).
Femoral neck fractures
Hip fractures represent a significant public health burden with around 70,000-75,000 cases a year with an estimated cost of £2 billion per a year, 10% of cases die within one month and a third die within 12 months(10). This is a marker of the complex co-morbidities of these patients, thus a thorough history into the cause of the fall needs to be undertaken and all patients should be managed within a multi-disciplinary environment with orthogeriatric input.
Management is nearly exclusively surgical with NICE recommending surgery on the day or day after admission with rapid correction or control of manageable co-morbidities to facility surgery(10).
Surgical options depend on the type of fracture. Firstly one must deduce if the fracture is intra or extra-capsular. In extra-capsular fractures blood supply to the femoral head is preserved and not threatened. If the fracture is above or including the lesser trochanter extramedullary fixation such as a sliding hip screw should be used, if subtrochanteric intramedullary fixation is advisable(10).
Intracapsular fractures are more complex. Due to the blood supply, as described above, the viability of the femoral head is threatened and avascular necrosis may occur. Fixation technique decision is dependent on the degree of displacement. Displacement is judged on plain film radiographs with both AP and lateral views assessed. Gardens classification is used to classify femoral neck fractures. Non displaced fractures (Gardners I and II) undergo fixation with cancellous scews or sliding hip screw. Displaced fractures (Gardners III and IV) require arthroplasty due to disruption of the blood and high risk of avascular necrosis , this can be total hip replacement or hemiarthroplasty(10). Indications for total hip replacement are defined by NICE as the following:
· Were able to walk independently out of doors with no more than the use of a stick and
· Are not cognitively impaired and
· Are medically fit for anaesthesia and the procedure
Post operatively early mobilization is the aim with multi-disciplinary rehabilitation and future falls prevention.
Pain secondary to osteoarthritis of the hip joint is present in 12% of adults of 65 years and above(11). Osteoarthritis of the hip may be primary or secondary to previous infection, injury or disease. Osteoarthritis of the hip joint has a worse prognosis than that of the hand or knee with a significant proportion requiring operative management at five years(11).
Pain is often the primary complaint, this can be felt in the anterior groin or it can be more generalized over the buttock and down to the knee. Patients may well complain that they find it hard to put on their shoes or cut their toe nails. Key signs on examination are an antalgic gait, muscle wasting, painful/reduced range of motion (internal rotation is the first effected), in later stages a fixed flexion deformity can be found(11).
Diagnosis can be made clinically, however AP plain film radiographs of the pelvis may well be useful.
Treatment should be individualized to patient factors. Education, strengthening with physiotherapy input, weight loss (if required), activity modification and assistive devices should be provided. Alongside this appropriate analgesia is needed. This should initially be paracetamol +/- non-steroidal anti-inflammatory drugs (NSAIDs). If prescribing a NSAID a proton-pump inhibitor should be co-prescribed and NSAIDs are not suitable/appropriate for all patients. Some may add weak opioids such as codeine however the evidence for this is poor(11). Intra-articular injection can also be considered; this may also provide diagnostic information.
If a patient continues to suffer from significant symptoms and pain operative intervention may be considered. Surgical options consist of arthroscopy, osteotomy, hip resurfacing and replacement(12). Patients age and degree of arthritic changes are key factors in the decision making process.
Developmental dysplasia of the hip (DDH)
DDH is a spectrum of disease ranging from mild dysplasia of the acetabulum to irreducible dislocation. 1-1.5 in 1000 live births are affected and it is more common in female patients, breech presentation and intra-uterine overcrowding(13, 14). The left hip is more commonly affected(13, 14).
In the neonate DDH is asymptomatic and therefore is screened for with Barlow and Ortolani tests. After the age of around 3 months the tissues begin to tighten and the aforementioned tests become unreliable, signs at this stage will be loss of abduction, apparent shortening of the thigh (Galeazzi sign) and asymmetrical skinfolds (however may be present in normal individuals)(13). After the child begins to walk other signs such as a trandelenburg gait and leg-length discrepancy will become apparent.
Ultrasonography prior to femoral head ossification (4-6 months) and plain film radiographs after ossification are the mainstay of investigation(13, 14).
Treatment depends on the age of diagnosis. Ultimately the aim is to maintain a reduced hip joint providing the optimal environment for normal hip development. As age at diagnosis increases this is harder to achieve, potential for hip remodeling reduces and more complex treatments are required. The following gives an overview of treatment options available according to age(13-15):
Under 6 months
· Splintage usually with a Pavlik harness
· Monitor with USS
6 months to 18 months
· Closed reduction (+/- adductor tenotomy)
o If difficulty in reduction consider arthrogram to assess if soft tissue is blocking reduction
· If closed reduction fails open reduction
· Reduction (closed or open) is held with a hip spica cast
18 months to 3 years
· Open reduction (+/- osteotomy)
3 to 8 years
· Open reduction and osteotomy
Over 8 years
· Can be treated non-surgically or with osteotomy
· Irrespective of above management choice must plan for a total hip replacement in adult life
Development: Derived from the mesoderm.
Blood supply: Retinacular vessels (branches of the circumflex vessels) are the predominant blood supply for the femoral head. Branches of the internal iliac artery supply the acetabulum.
Nerve supply: Innervation of the hip joint is from the femoral, obturator, sciatic nerve, superior gluteal and nerve to the quadratus femoris.
The hip joint is a major load bearing ball and socket joint connecting the pelvis to the lower limb. The joint is very stable but retains multi-axial movement. Pathological processes can occur in all stages of life and may well require surgical intervention.
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2 Wheeless C. Embryology of the Hip. In: Wheeless C, editor. Wheeless' Textbook of Orthopaedics: Duke Orthopaedics; 2013.
3 Moore KL, Dalley AF, II, Agur AMR. Clinically oriented anatomy. 5th ed. ed. Philadelphia, Pa. ; London: Lippincott Williams & Wilkins; 2006.
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5 Hoffmann R, Haas N. Fractures of the femoral neck (31-B). [cited 2016 10/3/16]; Available from: https://www2.aofoundation.org/wps/portal/!ut/p/a0/04_Sj9CPykssy0xPLMnMz0vMAfGjzOKN_A0M3D2DDbz9_UMMDRyDXQ3dw9wMDAx8jfULsh0VAdAsNSU!/?bone=Femur&segment=Proximal&soloState=lyteframe&contentUrl=srg/popup/further_reading/PFxM2/31/661_31_fem_neck_fxs_gen_consid.jsp
6 Itokazu M, Takahashi K, Matsunaga T, et al. A study of the arterial supply of the human acetabulum using a corrosion casting method. Clin Anat. 1997;10(2):77-81.
7 Hilton law. Farlex Partner Medical Dictionary; 2012.
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9 Cheatham SW, Kolber MJ. Orthopedic management of the hip and pelvis. St. Louis, Missouri: Elsevier, Inc.; 2016.
10 NICE. Hip fracture: management. National Institute for Health and Excellence Guidance. 2011 22/06/11.
11 NICE. Osteoarthritis. Clinical Knowledge Summaries. 2015.
12 Gandhi R, Perruccio AV, Mahomed NN. Surgical management of hip osteoarthritis. CMAJ. 2014 Mar 18;186(5):347-55.
13 Sankar W, Horn D, Wells L, Dormans J. The Hip. In: Kliegman R, Behrman RE, Nelson WE, editors. Nelson textbook of pediatrics. Edition 20 ed. Phialdelphia, PA: Elsevier; 2016. p. 3274-83.
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