Clinical Background

Arthritis of the hip can result from many causes, such as childhood sepsis, slipped capital epiphysis, and rheumatoid arthritis. About 30% of all patients with hip arthritis have a mild form of acetabular dysplasia (a shallow socket), and 30% have a retroverted socket. Both of these conditions reduce the contact area of the femoral head in the acetabulum, which increases the pressure and makes wear more likely. Approximately 30% of patients have no obvious risk factors.

Arthritis of the hip is marked by progressive loss of articular cartilage with joint space narrowing and pain. Stiffness encourages development of osteophyte formation (bone spurs), which in turn leads to further stiffness, making it difficult for the patient to put on socks and shoes. This eventually leads to the general picture of shortening, adduction deformity, and external rotation of the hip, often with a fixed flexion contracture. Bone loss usually occurs slowly, but with osteonecrosis occasionally it occurs precipitously.

General Features of Osteoarthritis

According to Dieppe (1984), the following are general features of osteoarthritis:

Primary Symptoms and Signs of Osteoarthritis

Classification of Hip Arthritis

The radiographic appearance of OA can be classified as (1) concentric, in which there is uniform loss of articular cartilage, (2) downward and medial migration of the femoral head, or (3) upward migration and superolateral migration of the femoral head. This is important if a corrective osteotomy is considered but is otherwise of no significance.

Diagnosis of Hip Arthritis

Hip pain can be simulated by referred pain from the spine, L3-4 sciatica, and stenosis of the internal iliac artery. Causes of referred pain must be ruled out. The classic clinical test for hip arthritis is internal rotation of the hip in flexion. With hip arthritis, this internal rotation is limited and painful.

Differential diagnoses include hip dislocation, hip fracture, pelvic fracture or disruption, entrapment of the lateral femoral cutaneous nerve, FAI or labral pathology, tendinitis of the piriformis or gluteus maximus or minimus tendons, trochanteric bursitis, L3-4 sciatica, spinal referred pain, internal iliac artery stenosis, and strain or contusion of the quadriceps or hamstring muscles.

Radiographic examination includes an anteroposterior (AP) view of the pelvis and AP and lateral views of the hip. The lateral view must be a modified frog-leg lateral or Lauenstein. A shoot-through lateral is of no value to the surgeon because it gives a distorted picture of the femur. Serologic investigations are seldom required. The only indication for further imaging studies such as bone scanning and magnetic resonance (MRI) is suspected osteonecrosis in the absence of radiographic findings.

The American College of Rheumatology lists several criteria for the diagnosis of OA of the hip.

Treatment of Hip Arthritis

Nonoperative Treatment

Nonoperative treatment is initially indicated for nearly all patients with hip osteoarthritis. This may include activity modifications, assistive devices, and medications. Although some high-impact activities, such as running and jumping, should be avoided, it is important to maintain as much activity and joint motion as possible. Swimming, cycling, and leisurely walking are all low-impact activities that can help maintain range of motion, strength, and function. Staying active also can help with weight loss, which is an important part of the management of hip arthritis. For patients who are overweight, losing 20 pounds or more may decrease pain and delay the need for surgery.

A cane in the opposite hand helps to unload the hip significantly (Fig. 6-1). A properly fitted cane should reach the top of the greater trochanter of the patient’s hip while wearing shoes. Doing stretching and strengthening exercises or joining a yoga class can be of surprising value in terms of regaining ROM because it is not uncommon that stiffness of periarticular structures (e.g., the inability to put on shoes and socks) rather than pain makes surgery necessary.

Figure 6-1 Use of a cane redirects the force across the hip. Without the cane, the resultant force across the hip is about three times body weight because the force of the abductors acts on the greater trochanter to offset body weight and levels the pelvis in single stance.

(Redrawn from Kyle RF. Fractures of the hip. In Gustilo RB, Kyle RF, Templeton D (eds.). Fractures and Dislocations. St. Louis: Mosby, 1993.)

Operative Options for Hip Arthritis

Osteotomies, such as pelvic and intertrochanteric osteotomies, were popular in the past, and they still may have a limited role in selected situations. Fusion still does have a role but in very early childhood only. The mainstay of surgical treatment is total hip replacement (Fig. 6-2). In general, for elderly patients with low activity demands, both the acetabular and the stem components can be cemented. For patients who are young and high demand, the current trend is to use noncemented implants. These are only general guidelines. In revisions with poor-quality bone, the surgeon makes fixation choices based on intraoperative findings.

Figure 6-2 Total hip replacement.

Weight-bearing restrictions are different after arthroplasty with cemented and cementless hip devices. Cement is as strong as it will ever be 15 minutes after insertion. Some surgeons believe that some weightbearing protection should be provided until the bone at the interface with the cement (which has been damaged by mechanical and thermal trauma) has reconstituted with the development of a peri-implant bone plate. This phenomenon takes 6 weeks. Most surgeons, however, believe that the initial stability achieved with cement fixation is adequate to allow immediate full weightbearing with a cane or walker.

With a noncemented hip prosthesis, the initial fixation is press-fit, and maximal implant fixation is unlikely to be achieved until some tissue ongrowth or ingrowth into the implant has been established. Stability is usually adequate by 6 weeks. However, maximal stability is probably not achieved until approximately 6 months with noncemented prostheses. For these reasons, many surgeons advocate toe-touch weightbearing for the first 6 weeks. Other surgeons believe that the initial stability achieved is adequate to allow weightbearing as tolerated immediately after surgery.

Straight-leg raises (SLR) can produce very large out-of-plane loads on the hip and should be avoided in the postoperative period after total hip arthroplasty. Side-leg-lifting in the lying position also produces large loads on the hip. Even vigorous isometric contractions of the hip abductors should be practiced with caution, especially if a trochanteric osteotomy has been done.

Initial rotational resistance of a noncemented hip may be low, and it may be preferable to protect the hip from large rotational forces for 6 weeks or more. The most common rotational load comes when arising from a sitting position, so pushing with hands from a chair is strongly recommended.

After full weightbearing is established, it is essential that the patient continue to use a cane in the contralateral hand until the limp stops. This helps prevent the development of a Trendelenburg gait, which may be difficult to eradicate at a later date. In some difficult revisions in which implant or bone stability has been difficult to establish, a patient may be advised to continue to use a cane indefinitely. In general, when a patient gets up and walks away, forgetting about the cane, this is an indicator that the cane may be safely discarded.

Preoperative Management

Patient education regarding postoperative pain management, restrictions, independent walking, and proper rehabilitation is an important first step in achieving satisfactory results after THR. Preoperative classes can facilitate patients’ understanding of reasonable expectations of recovery, increase their motivation, and help expedite the rehabilitation learning process(Giraduet-Le Quintrec et al. 2003). Vukomanovic et al. reported that patients who both performed the “postoperative” exercises and received preoperative education demonstrated the ability to perform functional activities significantly earlier than those who were randomly assigned to the control group. These functional activities included being able to walk up and down stairs earlier, use the toilet and chair sooner, transfer independently, and ambulate independently.

Patient education also has been shown to be directly related to faster postoperative ambulation, reductions in hospital length of stay, and less use of narcotic pain medications (Spaulding 1995). A major part of preoperative educational classes should be dedicated to prevention of postoperative dislocation by appropriate explanation of hip precautions.

Although several studies have shown that preoperative strengthening exercises have a significant correlation with longer postoperative walking distance and may improve early return to ambulatory function after THR (Gilbey et al. 2003; Wang et al. 2002; Whitney and Parkman 2002), others have shown that these exercises have no significant impact on the outcomes (Gocen et al. 2004; Rooks et al. 2006).

Surgical Approach

One of the factors influencing postoperative recovery and rehabilitation is the surgical approach. The patient’s gait may be compromised with approaches in which the hip abductors are altered (i.e., lateral or anterolateral approaches). Inadequate repair or weakness of the abductor muscles after these approaches may result in prolonged limping. The posterolateral approach spares the hip abductors but is associated with a slightly higher dislocation rate. This dislocation rate can be reduced with the use of larger femoral heads and proper repair of the posterior soft tissues (Pellicci et al. 1998; Woo and Morrey, 1982). The direct anterior approach, although theoretically appealing, is technically demanding and may require fracture table and intraoperative fluoroscopy (Peak et al. 2005). Minimally invasive THR has been widely marketed, but the claims of significantly reduced pain, less morbidity, better function, and improved patient satisfaction appear to be unfounded (Khan et al. 2009). Based on recent reports, minimally invasive THR does not appear to affect the short-term or intermediate-term outcomes after the THR (Howell et al. 2004; Inaba et al. 2005; Lawlor 2005). Complications of minimally invasive THR include wound-healing problems, component malposition, and increased risk of femoral fractures (Howell et al. 2004; Lawlor 2005).

Multimodal Pain Management

Severe pain after THR is one of the greatest fears patients have before surgery and is the leading cause of delayed discharge. Pain remains a poorly understood, complex phenomenon that plays a significant role in limiting patients’ functional recovery and participation in postoperative physical therapy (Ranawat and Ranawat 2007). Optimal pain control promotes earlier ambulation and faster return to normal gait (Singelyn et al. 1998). Decreased postoperative range of motion due to pain commonly contributes to arthrofibrosis and inferior results (Ryu et al. 1993). A multimodal pain regimen is a relatively new concept that has shown excellent results in terms of improving postoperative pain, reducing the need for narcotic medications and increasing patients’ motivation and participation in postoperative physical therapy (Brown et al. 2009; Busch et al. 2006; Hebl et al. 2005; Maheshwari et al. 2006; Peters et al. 2006). The key to multimodal pain control is the use of various pain medications with different mechanisms of action that results in superior pain control while minimizing their adverse side effects. Several postoperative pain control protocols exist, including patient-controlled anesthesia pumps (PCA), femoral nerve blocks (FNBs), continuous or one-time psoas compartment block (cPCB), and continuous lumbar plexus block (cLPB) (Becchi et al. 2008; Siddiqui et al. 2007). The use of local infiltration through an intra-articular catheter after THR has been shown to reduce the hospital stay and reduce the opioid-related side effects, such as nausea and vomiting, compared to continuous epidural infusion (Andersen et al. 2007). Local periarticular injections have also been used in a multimodal pain regimen that has been shown to reduce postoperative pain and improve patient satisfaction and functional recovery (Pagnano et al. 2006; Parvataneni et al. 2007).

Hip Precautions

Postoperative hip restrictions are used to protect the soft tissue repair after a posterior approach and thereby avoid hip dislocation (Masonis and Bourne 2002). Table 6-2 presents the common precautions associated with each surgical approach; however, variations may exist regionally. These precautions can be difficult to adhere to and may interfere with the postoperative rehabilitation process (Peak et al. 2005). Dislocation after THA through the posterior approach commonly occurs when the hip is adducted past midline, internally rotated, and flexed more than 90 degrees. To prevent this, an abduction pillow (Fig. 7-48 in Chapter 7) is placed between the patient’s knees while in bed or a small cushion can be situated between the thighs while sitting (Rao and Bronstein 1991). In some cases, especially in revisions or in patients who are noncompliant, it may be necessary to use knee immobilizers or hip abduction orthoses for 6 to 12 weeks postoperatively to restrict hip adduction and flexion (Venditolli et al. 2006).

Table 6-2 Precautions Associated with Total Hip Arthroplasty Surgical Approaches

After an anterior or anterolateral approach, extreme external rotation, adduction, and extension should be avoided. Several reports have shown that removal of hip precautions after the anterolateral approach results in a faster return to normal activities with higher patient satisfaction and no ill effects on short-term dislocation rates (Peak et al. 2005; Talbot et al. 2002).

Postoperative Total Hip Arthroplasty Rehabilitation Programs

Although a wide variety of exercise programs exist based on surgeon preference and geographic location, most protocols include quadriceps sets, gluteal sets, ankle pumps, and active hip flexion (heel slides) exercises (Enloe et al. 1996). Progressive hip abductor strengthening is also advocated, as the abductors maintain the pelvis level during the stance phase and prevent tilting of the contralateral hip during the swing phase (Enloe et al. 1996; Soderberg 1986). Most exercise programs address this issue initially by concentric hip abduction in a supine position and later through isometric hip abduction against resistance (Munin et al. 1995). The straight-leg raising exercise has been shown to apply a force of 1.5 to 1.8 times body weight and should be allowed only when partial or full weightbearing is permitted (Davy et al. 1988). If pain occurs, hip flexion and knee extension exercises can be done separately with placement of a bolster under the knee to minimize hip stress (Davy et al. 1988; Trudelle-Jackson et al. 2002). Several reports have shown persistent quadriceps atrophy or weak thigh flexors of the operated hip compared to the contralateral hip (Bertocci et al. 2004; Reardon et al. 2001; Shih et al. 1994).

Functional tasks of daily living targeted in the rehabilitation program include weight transfer to the nonoperated hip, gait training on both level and uneven surfaces, stair climbing, and lower extremity dressing. Transferring of weight to the uninvolved side is initiated by leading with the nonoperated limb both into and out of bed and then is progressed to both sides of the bed. This method is also used with stair climbing: Patients are instructed to lead with the uninvolved hip while ascending and lead with the operated hip while descending the stairs to optimize control of body weight through the uninvolved leg (Strickland et al. 1992).

Weightbearing

Weightbearing restrictions after hip replacement, such as toe-touch weightbearing (TTWB) or partial weightbearing (PWB), directly affect the level of functional independence after surgery. PWB refers to 30% to 50% of the body weight, but studies have shown that patients have difficulty estimating and maintaining this percentage and commonly violate the restricted weightbearing (Davy et al. 1988). In TTWB, no more than 10% of body weight should be applied. TTWB is preferred over nonweightbearing (NWB) because the latter may actually create greater pressures over the hip joint as a result of muscle forces maintaining the correct pelvic positioning (Davy et al. 1988). Full weightbearing (FWB) has been shown to promote faster recovery and shorter hospital stays (Kishida et al. 2001). This is a result of reduced reliance on the upper extremities for weightbearing, resulting in earlier strengthening of the operative hip abductors and improved functional outcomes.

Assistive devices such as walkers, crutches, and canes are used to unload the operated joint and provide support and balance (Holder et al. 1993; Strickland et al. 1992). Progression from one to another is dependent on several factors such as age, comorbidities, and weightbearing restrictions. Walkers are usually the first choice after THR and provide the greatest stability by increasing the patient’s base of support and unloading the affected leg (Davy et al. 1988). Because walkers require the use of both hands, carrying objects and performing self-care activities are challenging. In addition, walkers occasionally do not fit through doorways and are not recommended for use on stairs. Rolling walkers have higher self-selected walking speeds than standard walkers (Palmer and Toms 1992). Most patients advance easily from gait training with a walker to crutches or a cane. Axillary and forearm crutches are more appropriate for younger, more agile patients because they allow faster gait and yield better energy efficiency in NWB healthy subjects (Holder et al. 1993), but they have the least stability and require more control of the lower extremity and overall balance (Palmer et al. 1992). A potential complication of axillary crutches is axillary nerve compression injuries from incorrect use (O’Sullivan and Schmitz 1988). Canes are usually used on the contralateral side of the hip replacement and can transfer 10% to 20% of body weight by decreasing vertical hip contact forces (Brander et al. 1994; Deathe et al. 1993; Stineman et al. 1996). The basic function of a cane is to extend the base of support and to provide stability. Canes should be used only for patients who are fully weightbearing. Canes are inexpensive, allow a reciprocal walking pattern, can be used on stairs, and can be sized according to the patients’ height. The crook of the handle should be even with the radial styloid process when the elbow is flexed at 15 to 30 degrees (O’Sullivan and Schmitz 1988).

Levels of Rehabilitative Care

Different rehabilitation settings include acute hospital care, inpatient rehabilitation, skilled nursing facilities, and home or outpatient rehabilitation centers. Selecting the appropriate postoperative rehabilitation that best serves the patient is often confusing to both the patient and health care professionals. In acute hospital care, postoperative physical therapy is usually started on the same day of surgery or the next morning. The goals for the first physical therapy session are to assess the patient’s mobility status and to initiate therapeutic activities. With the patient lying supine in the bed, the physical therapist should observe the patient’s positioning, assess for signs of a deep vein thrombosis (DVT) (Table 6-3), note the state of the dressing, and record the ROM and strength of the uninvolved leg. If signs of a DVT are present or if there is excessive drainage noted on the dressing, the nursing staff should be immediately informed prior to continuing the treatment session.

Table 6-3 Signs Associated with a Deep Vein Thrombosis

Initial training includes strength assessments, sit-to-stand transfers, and gait and balance teaching. Transfers from bed to chair are usually done twice a day for half an hour at a time. Patient education further involves lower extremity dressing, bathing, and toilet transfers using appropriate equipment to maintain hip precautions. Transfers and gait training exercises are advanced depending on the patients’ weightbearing status, preoperative level of ambulation, age, and amount of improvement, progressing from simple walking to attempting curbs and ramps based on the patient’s needs. Medical management includes aggressive multimodal pain control, bowel regimens, DVT prophylaxis, and management of any comorbidities.

Therapeutic exercises initiated during the initial visit may consist of lower extremity isometrics (quadriceps, hamstring, gluteal sets) and ankle pumps. Initially, a patient may be able to tolerate only passive ROM; however, he or she should be able to demonstrate increased active ROM tolerance over the course of the inpatient stay. Therapeutic exercises frequently are added daily to the patient’s routine. Table 6-4 presents a sample therapeutic exercise progression during the first postoperative week.

Table 6-4 Sample Week 1 Total Hip Replacement Postoperative Exercise Program*

* This sample program is based on a posterior surgical approach (see also page 435).

Comprehensive inpatient rehabilitation is different from acute hospital care because it is more focused on physical therapy and interdisciplinary treatment in combination with intensive family training. Inpatient rehabilitation is reserved for patients who require more than a few days of continuous skilled care, are able to physically tolerate at least 3 hours of therapy per day, and have a good chance of returning home within a reasonable time frame (Stineman et al. 1996). Medical management is similar to the acute hospital care setting. Reports have shown that older patients without family support and patients with comorbid medical conditions usually need inpatient rehabilitation after THR (Munin et al. 1995; Weingarten et al. 1994). The subacute nursing facility (SNF) was developed as a complement to inpatient rehabilitation and has grown as an alternative to it. The SNF is reserved for patients who cannot tolerate the 3 hours of therapy per day required in an inpatient rehabilitation program and are not at risk for medical instability (Haffey and Welsh 1995).

Because of recent increasing pressure to discharge patients more quickly after surgery, it is important to assess if a patient can be safely discharged home. With improved surgical and pain management techniques, some patients may go home as early as the first postoperative day, whereas others with more comorbidities require longer lengths of hospital stay.

General criteria for home discharge include the following:

Management of Common Problems After Total Hip Replacement

Outpatient Total Hip Arthroplasty Physical Therapy Protocol

Typically, a patient should be either able to demonstrate or be working toward the following clinical goals:

Exercises to increase muscle strength include the following:

Progressive overload to the muscles can be applied manually by the application of ankle weights or with the use of elastic resistance bands. The initial exercise prescription should consist of one to three sets of 15 to 20 repetitions. This volume of training will help to improve muscular endurance while minimizing the risk of excessive postexercise muscular soreness or pain. As endurance capacity increases, strength training can be increased to volumes of two to four sets of 6 to 10 repetitions. Table 6-5 presents frequently prescribed therapeutic exercises that address muscular weakness. The exercises are grouped by the muscles trained and in the order of difficulty.

Table 6-5 Therapeutic Exercises Frequently Prescribed in the Outpatient Orthopedic Physical Therapy Setting

* Exercises are presented by their relative degree of difficulty.

Return to Sport After Total Hip Replacement

Physical activity levels may have an impact on the lifespan of the total hip replacement. Wear and tear on the replaced joint or a traumatic event may necessitate a revision surgery at a later date; however, having a hip replaced does not mean that one must end his or her recreational or sport pursuits. Exercise and activity are necessary for maintaining overall health. Instead of restricting activity, physicians have developed recommendations and guidelines for those who wish to return to activities that are more strenuous than walking. Table 6-6 presents examples of activities and sports, their associated levels of impact on the hip replacement, and recommendations as to the safety of performing and participating in a particular sport.

Table 6-6 Sport Participation Recommendations and Associated Levels of Impact on the Total Joint Replacement