Total Hip Arthroplasty
Maya C. Manning, PT, DPT, CSCS
Matthew P. Titmuss, PT, DPT
Jessica Bloch, MS, OTR/L
Alejandro Gonzalez Della Valle, MD
Dr. Gonzalez Della Valle or an immediate family member serves as a paid consultant to Link Orthopaedics, Merz Pharmaceuticals, Orthodevelopment, and Orthosensor. None of the following authors or any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this article: Dr. Bloch, Dr. Caspi, and Dr. Titmuss.
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Overview of Total Hip Arthroplasty
Modern total hip arthroplasty (THA), perfected by the pioneering work of Sir John Charley, has revolutionized the treatment of end-stage arthritis of the hip, and has relieved the pain and restored function of millions of patients worldwide. The Agency for Healthcare Research and Quality reported that over 420,000 THAs were performed in the United States during 2012. The number of THAs is expected to increase six times by the year 2030.
The majority of THAs in the United States are performed on patients with idiopathic arthritis or hip fractures. Other indications include rheumatoid arthritis, avascular necrosis, posttraumatic arthritis, psoriatic arthritis, systemic lupus erythematosus, and tumor resection.
Patients considering elective THA surgery usually present with progressive severe hip pain and limitation of motion associated with extensive cartilage loss. Patients usually complain of difficulty performing activities of daily living (ADLs) including standing, walking, sitting, negotiating stairs, and sleeping. With the progression of arthritis, contractures (often in flexion and external rotation) develop, as well as limitation of range of motion (ROM). The ideal patients for elective THA have usually tried a period of conservative measures aimed at relieving pain and maintaining function.
Contraindications to THA include unexplained hip pain in the absence of pathology, acute or chronic hip infection, Charcot arthropathy, inability to follow postoperative recommendations and precautions, a well-functioning, painless hip arthrodesis or resection arthroplasty, and chronic medical conditions (uncontrolled diabetes; or severe heart, lung, neurologic, vascular, or systemic diseases).
Careful preoperative patient assessment and meticulous surgical planning are important to increase the likelihood of success. During history taking and physical examination, the patient’s complaints and expectations for function and activity following surgery are assessed and discussed to ensure that they are realistic and attainable by the surgeon. Assessment of abnormal gait patterns, neurovascular condition, functional and actual leg length discrepancy, ROM and the presence of fixed or correctable pelvic obliquity are necessary. Preoperative planning consists of generating a surgical plan utilizing the information obtained during the physical examination along with standardized radiographs with known magnification. The plan allows for the anticipation of implant sizes, position, and fixation. In addition, it determines the position of the bone cuts that will restore leg length, offset, and other features of a biomechanically sound reconstruction. A precise reconstitution of hip biomechanics is essential to ensure a stable and durable reconstruction. Malposition of prosthetic components or failure to restore offset and/or leg length can result in postoperative hip instability (including dislocation), premature wear, and patient dissatisfaction.
Different surgical approaches have been used, including anterior, anterolateral, posterolateral, and transtrochanteric. Despite careful surgical technique, each of the surgical approaches will cause a controlled amount of soft-tissue damage. The type of approach will dictate the type of postoperative precautions that the patient needs to follow. The surgical approach used for each individual patient should be well documented and taken into consideration by the surgical team (including physical therapists, nurses, physician assistants, and so on).
The characteristics of each surgical approach are described here.
Posterolateral: The incision is located in the posterior aspect of the greater trochanter and divides the fibers of the gluteus maximus muscle. A detachment and subsequent repair of the external rotators (conjoined tendon, quadratus femoris), and posterior capsule is necessary, and creates a relative weak posterior soft-tissue envelope. The anterior capsule remains intact.
Anterolateral: The incision is located in the anterior aspect of the greater trochanter and divides the fibers of the gluteus medius muscle. A detachment and subsequent repair of the anterior capsule is necessary, and creates a relative weak anterior soft-tissue envelope. The division of the gluteus medius fibers can create transient postoperative abductor weakness. The posterior capsule remains intact.
Anterior: The incision is made distal and lateral to the anterosuperior iliac spine. The dissection is carried out between the tensor fascia lata and rectus femoris. The limited working space and reduced visualization of structures may require resection of the anterior joint capsule and release of the piriformis tendon, the use of intraoperative fluoroscopy, and specially designed traction surgical tables. The approach compromises the anterior soft-tissue envelope of the hip.
Transtrochanteric (rarely used): The incision is made centered on the trochanter and a trochanteric osteotomy is performed for wide access to the joint. The approach requires an additional anterior capsulotomy. Reattachment and subsequent healing of the greater trochanteric osteotomy are necessary for a successful outcome. If nonunion of the trochanteric osteotomy develops, patients may experience pain, abductor lurch, and hip instability.
The socket and stem of the THA can be fixed with acrylic cement or relying on cementless press-fit (Figure 36.1). Today, the majority of sockets are fixed without cement. This requires reaming the acetabular cavity to a diameter 1 to 2 mm smaller than the socket to be implanted. The socket has a porous surface onto which the native acetabular bone will grow. Acetabular screws are used when the bone quality is poor or in some acetabuli with bony anomalies. The femoral components can be fixed with or without acrylic cement. When cement fixation is used, there is immediate, stable fixation of the implant to the bone. The patients can bear weight as tolerated immediately following surgery. When cementless femoral fixation is used, the amount of weight that the patient can bear following surgery will be determined by the fit achieved during final stem insertion. Some patients with poor bone quality or less than perfect stem fit may benefit from a period of protected weight bearing.
Wound closure usually includes careful repair of the soft-tissue envelope disrupted by the surgical approach, thus the need to apply dislocation precautions that are specific to the surgical approach utilized (e.g., posterior dislocation precautions for a posterolateral approach and anterior dislocation precautions for an anterior and anterolateral approach.
The risk of medical and local complications of surgery is multifactorial and depends on surgeon and patient factors. They include infection, fracture, dislocation, loosening, neurologic and vascular damage, and thromboembolic disease. Gentle postoperative rehabilitation plays a crucial role in preventing pain, dislocation, thromboembolism, and wound complications.
In the last two decades, emphasis has been placed on reducing hospital stay and overall hospital costs associated with the procedure. Consequently, in-hospital rehabilitation guidelines for recovery following THA have evolved. Therapy after surgery focuses on early mobilization and preparation for a prompt and safe discharge. Postdischarge rehabilitation programs have been developed to achieve a full recovery. Preoperative surgical rehabilitation can also be used.
Acute Phase (First Several Days–2 Weeks)
The initial phase of rehabilitation includes the patient’s immediate recovery from surgery and discharge from hospital to home or a rehabilitation facility. In this phase, there is a strong emphasis on patient and family education, ADL training, transfer training and gait training, and initiation of a therapeutic exercise program.
Prior to surgery, patients are often instructed in a classroom setting regarding what to do in the days before surgery, what to expect on the day of their surgery and the days following while in the hospital, and discharge planning. A physical therapist or nurse may give a presentation, during which postoperative hip precautions, basic exercises, basic postoperative mobility, and expected changes in ADLs are reviewed. Online resources may complement this process. This preoperative class addresses patients’ concerns prior to surgery and teaches them how to set up their homes to accommodate their recovery appropriately before coming to the hospital. Equipment may be recommended by an occupational therapist to assist with ADLs.
Total Hip Precautions
Patients whose hip replacement is performed through a posterolateral approach are instructed to follow posterolateral hip precautions for 6 to 8 weeks postoperatively in order to allow for the hip capsule to heal, and to reduce the chance of hip dislocation.
The postoperative precautions include:
No hip flexion greater than 90°
No hip adduction past midline
No hip internal rotation past neutral
For the patients that undergo THA through an anterior approach, the postoperative precautions include:
No hip external rotation past neutral
No excessive hip extension
Transfer and Gait Training
In the days immediately following surgery, patients are instructed to transfer in and out of bed on the same side as the operated limb in order to avoid hip internal rotation. If the patient is able to do so with adequate control while maintaining hip precautions, he can be instructed on exiting and entering on either side. For patients with bilateral THA, they are instructed to use the same side of the bed that they will use at home.
With length of stay (LOS) decreasing, early mobility is greatly encouraged. It has been shown that early mobilization following THA decreases hospital LOS. Patients who are medically stable to participate with the physical therapist are often able to have their first session on the day of surgery, several hours after coming out of the operating room. Ambulation is initiated with a rolling walker to allow for upper extremity weight bearing, to support the surgical lower extremity, and provide increased stability and patient confidence. Following an uncomplicated THA, the majority of patients are allowed to bear weight as tolerated (WBAT). Activity level on the day of surgery ranges from dangling at the bedside to walking up to approximately 100 feet with a rolling walker.
On the day of surgery prior to getting up for the first time, the postoperative radiograph is reviewed to confirm that no fracture or dislocation has occurred after surgery. The goal on postoperative day (POD) #0 is for the physical therapist to evaluate the strength and sensation in the lower extremities, educate the patient on his exercises and precautions and, if appropriate, ambulate a short distance. On POD #1, the patient may have several sessions of physical therapy, spaced throughout the day and designed to progress independence with transfers, ambulation, therapeutic exercises, and overall tolerance for activity. If the patient is able to demonstrate a nonantalgic, step-through gait pattern with good balance, he will be progressed to walking with a cane or crutches by the afternoon of POD #1 or as early as the morning of POD #1. When the patient is able to ambulate with equal step length bilaterally using a cane, he will progress to ascending and descending stairs with use of a cane and handrail, following a step-to pattern. This usually occurs in the afternoon of POD #1.
On POD #2, patients work on developing safe and independent ADL. This includes transferring, ambulation with an appropriate assistive device, ascending/descending stairs (nonreciprocal), and independence with a home exercise program. Some patients may require further reinforcement and education in order to ensure a safe home discharge. Once they are able to perform all activities safely and independently, they are discharged by the physical therapist and considered safe to go home. Some patients will be discharged home on POD #1, but most patients are ready to be discharged home on POD #2. Few patients are discharged to rehabilitation facilities.
Patients are encouraged to sit in a chair several times per day, at least for all meals. However, sitting is limited to less than 1 hour each time in order to avoid increased pain, swelling, and stiffness. Hospital staff play an important role in assisting patients out of bed at their meal times, and provide additional opportunities for patients to ambulate, helping to reduce stiffness that may occur with reduced mobility.
During the first session of physical therapy following surgery, patients are instructed on basic bed exercises to perform on an hourly basis. Initial exercises aim to promote circulation in the lower extremities, reducing the chance of a blood clot and promoting reactivation of the lower extremity (LE) muscles disturbed during the surgery. A note card with written instructions that include pictures of all exercises, how often to perform them, and any precautions is a useful aid for patients.
Patients are instructed to perform these exercises 10 times an hour every hour while in bed.