HISTORY AND PHYSICAL EXAMINATION

The first step in planning for any surgical procedure is the taking of a detailed history and the performance of the physical examination. An accurate diagnosis cannot reliably be established without details about the patient’s history, review of symptoms, and physical examination findings. The history should begin with obtaining details of and hospital records from all prior surgical procedures and perioperative treatments. These records should contain information regarding implanted materials from previous operative notes. It is extremely helpful and efficient to request that the patient present these surgical records on his or her initial visit in order to provide the surgeon with valuable information regarding the prior procedure and the implants used.

Initial history taking should begin with a discussion about the patient’s chief complaint. The location and nature of the patient’s pain can guide the surgeon to the proper diagnosis. Acetabular component loosening is often associated with groin pain, whereas startup pain (rising from a seated position) localized to the thigh is more indicative of femoral component loosening. Subluxation or dislocation may be indicated by a complaint of a sensation of hip “clicking” or “popping” rather than by a history of a documented frank dislocation.

A thorough review of the patient’s medical history, along with a complete review of systems, will help the surgeon to identify any potential factors that may lead to perioperative complications and will allow the surgeon an opportunity to medically treat the patient or to optimize the patient’s condition before the planned operation. The cardiac and pulmonary history is of utmost importance, along with any history of thromboembolic disorders or endocrine abnormalities such as diabetes mellitus. Furthermore, sources of potential or concurrent infection need to be discovered, and proper evaluation and treatment should be performed well in advance of the surgical procedure. Studies have confirmed that the rate of postoperative deep infection is influenced by advanced age, obesity, metabolic disease, steroid therapy, depressed immune status, rheumatoid disease, previous hip surgery, and prolonged preoperative hospitalization. Men with prostate disease and women with recurrent urinary tract infections should be referred to a urologist in the preoperative period. Dental caries are also a potential source of infection, and a preoperative dental examination is helpful to avoid any potential seeding of the involved surgical site. A history of delayed wound healing, persistent drainage, and prolonged use of postoperative antibiotics should alert the surgeon to be suspicious for infection. If infection is suspected, routine laboratory testing should be ordered and should include a complete blood count (CBC) with differential, sedimentation rate, and a C-reactive protein level, along with a hip aspiration. It is important to note that negative hip aspirations do not completely rule out infection and should be followed by intraoperative tissue sampling with frozen sections; the appropriate pathology department personnel must be alerted before the planned surgical date.

Patients with any history of chronic venous stasis ulcers, previous vascular bypass surgery, or absent distal pulses should be evaluated by a vascular surgeon. Patients with a history of cardiac bypass surgery, angioplasty, or coronary artery stenting should be evaluated by a cardiologist well in advance of the planned surgical date so that the need for any preoperative testing may be determined and so that the anesthesiologist may be alerted about any specific perioperative needs or postoperative intensive care monitoring requirements.

The physical examination is an invaluable resource that should be used to confirm any impressions made during the collection of the patient’s history. The physical examination findings give the surgeon a baseline for the postoperative evaluation. The physical examination should begin with the analysis of the patient’s gait. Use of ambulatory assistive devices, presence of a limp, or presence of a deformity of the lower extremity should be noted. The antalgic gait is a result of pain in all phases of ambulation with weight bearing and is characterized by a shortened stance phase indicating hip-joint disease. The Trendelenburg gait or abductor lurch indicates either paralysis or loss of continuity of the abductor musculature and is identified by observing the shift of the patient’s center of gravity over the affected extremity during the stance phase of gait. Weakness of the gluteus maximus creates the characteristic extensor lurch gait, which occurs by the shifting of the weight of the thorax posteriorly during hip extension. Quadriceps weakness prevents full knee extension at heel strike, and a foot drop is usually present with tibialis anterior weakness.

Inspection of previous surgical wounds should be routinely performed. Planning of the surgical incision is important in determining the approach for the surgical reconstruction, and although skin flap necrosis after hip surgery is rare, the maximum distance and angles used should be optimal to avoid this complication.

Limb length measurements should be obtained in order to allow possible surgical correction during the revision procedure. We measure the medial malleoli, clinically a more useful measurement. It is important to properly inform the patient that stability is a priority over leg length equality and that all measurements will be taken to re-create leg length equality if possible.

The active and passive ranges of motion of the hip should be identified, along with the strength of the hip girdle musculature. The gluteus maximus is the primary hip extensor, and approximately 30 degrees of hip extension can be expected in a normal patient. The iliopsoas is the primary hip flexor and typically allows 125 to 135 degrees of flexion. The adductor longus is the primary hip adductor and the gluteus medius is the primary hip abductor, allowing 20 to 30 degrees of hip adduction and 50 degrees of hip abduction, respectively. Patients with hip ankylosis or acetabular protrusion may require extensile exposures and trochanteric osteotomies, necessitating the appropriate implants and surgical equipment.

The vascular status of the involved extremity should always be evaluated, and any abnormal findings should be noted. The vascular examination should include evaluation of the femoral, popliteal, dorsalis pedis, and posterior tibialis pulses. Patients with absent pulses should be further evaluated by a vascular surgeon, and appropriate arterial or venous vascular studies should be performed.

RADIOGRAPHIC EVALUATION

The initial radiographic workup should include an anteroposterior (AP) view of the pelvis and both AP and lateral views of the involved hip. Internal rotation of the involved hip approximately 15 degrees on the AP view is helpful in eliminating the normal anteversion of the hip in order to allow an accurate measurement of the offset and neck-shaft angle. The AP view of the hip should extend beyond the tip of the prosthesis and cement for proper evaluation of component fixation and for planning for extraction as necessary. Obturator oblique and iliac oblique views (Judet views) along with CT scans are useful for evaluation of extensive acetabular and pelvic defects.

From an organizational standpoint it is easiest to look first at component fixation and next at the degree of bone damage present. Both acetabular and femoral component fixation is evaluated first. On the femoral side the component is either cemented or cementless. Three categories of cemented femoral component loosening have been identified: definite, probable, and possible loosening. Definite loosening is defined as evidence of component loosening within the cement mantle or cement mantle migration. Radiographic signs are progressive change in femoral component positioning within the cement mantle, cement fracture or fragmentation, deformation or fracture of the femoral component, and clear separation of the femoral component from the cement. Probable loosening is defined as a complete zone of radiolucency surrounding the cement-bone interface on at least a single radiographic view. Possible loosening is defined as radiolucency surrounding at least 50% of the cement-bone interface. From a practical standpoint, definite loosening indicates that the femoral component is debonded from the cement, and probable loosening indicates that the cement has debonded from the bone. Cemented acetabular components are definitely loose if there is a radiolucency between the cement and bone comprising 100% of the interface. Other signs of definite loosening include medial migration of the cup and cement, progressive change in the version of the component or disruption, and fracture of the acetabular bone stock.

Evaluation of uncemented components is slightly different from evaluation of cemented components. Acetabular component loosening is the same except that the interface under evaluation is bone-prosthesis instead of bone-cement. One additional sign of acetabular component loosening is screw fracture. Femoral component evaluation requires looking for signs of osseointegration as well as signs of instability. The Engh classification works the best, and components fall into three categories. A femoral component is classified as stable with bone ingrowth if there is no subsidence and there are spot welds and calcar atrophy (signs of bone ingrowth). A femoral component is classified as unstable if there is subsidence or change in component position. Furthermore, there are general signs of failure of bone ingrowth: no spot welds, calcar hypertrophy, distal pedestal formation, and complete radiolucency at the bone-prosthesis interface in the porous portion of the femoral component. Occasionally, femoral components seem stable but demonstrate fibrous fixation (no spot welds, complete radiolucency at the bone prosthesis interface).

Radiographs are essential in the preoperative period not only for accurate diagnosis but also for surgical planning, especially if operative notes from the previous surgical procedure are unavailable. Radiographs can be used to identify the previous components implanted and to help the surgeon to properly plan for the revision procedure, and they allow the operative team to have the necessary instruments available for both removal and reimplantation of the prosthesis. For the femoral side it is useful to note if the component is a monoblock or modular design. If the component is found to be well fixed and retained, the surgeon needs to be sure that appropriate acetabular liners are available for monoblock components, and modular heads and trial implants for modular components. For the acetabular side, shells with screws can be identified so that the proper instruments for removal can be obtained along with sharp curved osteotomes for shell removal with minimal bone stock loss.