The majority of inpatient orthopedics focus on the hip, knee, and spine. Improvements in orthopedic implants, techniques, and overall medical care have expanded indications for reconstructive efforts to restore function, reduce pain, and improve quality of life. This chapter reviews the most common major operations typically encountered in the hospital setting.

Anatomy

The hip, a ball and socket joint with articular cartilage, provides for load bearing and low-friction motion. The bony architecture supported by a fibrocartilaginous labrum, joint capsule, and traversing muscle groups provides stability. These muscle groups load the hip joint at 2 to 3 times the body weight and are highly sensitive to any changes in hip center of rotation or length of the lever arms. Synovial fluid provides nutrition to the avascular cartilage. The femoral head receives blood from the ascending branches off the medial circumflex femoral artery. Disruption of this retrograde blood supply may lead to avascular necrosis.

Any surgical approaches require significant soft tissue dissection to reach the hip joint. The most commonly used and most extensile posterior approach provides excellent visualization of the femur and acetabulum. The sciatic nerve is the main structure at risk. With meticulous repair following dissection of the posterior capsule, dislocation rates have been dramatically reduced. The lateral and anterior approaches both leave the posterior joint capsule intact resulting in low instability rates. Lateral approaches require hip abductor dissection and may lead to abductor insufficiency and a Trendelenburg gait. Anterior approaches provide limited exposure to any posterior structures. Trochanteric osteotomy provides extensile exposure but risks nonunion. The specific approach is chosen based on pathology, patient factors, and surgeon preference.

Total Hip Arthroplasty

Total hip arthroplasty (THA) can dramatically relieve pain and improve function (Table 65-1). Surgical candidates have generally tried and failed a conservative course of weight loss, analgesics, assistive devices, therapy, and activity modifications. Preoperative radiographs should confirm destruction of the hip joint and allow for surgical planning. Other causes of “hip pain” should be ruled out. Arthritis often coexists in the hip and spine, with true hip pain perceived in the groin and anterior thigh.

THA involves removal of the diseased hip joint and implantation of a prosthetic hip. Autologous blood transfusion may be discussed preoperatively. Perioperative blood salvage is an option in complex cases. Regional anesthesia may be associated with better initial outcomes than general anesthesia. This decision should be made in accord with the patient and anesthesiologist. The most significant factor associated with risk of postoperative transfusion is preoperative hemoglobin.

The prosthetic hip consists of a femoral component, an acetabular component, and a bearing/coupling surface. Fixation of the prosthesis is either cemented or cementless. Cemented THA are more commonly used for lower demand patients, due to concerns regarding loosening in higher demand patients. Cemented fixation provides an immediate mechanical bond to the host bone and achieves maximal stability within 24 hours. Generally recommended for physiologically younger patients, cementless fixation relies on an initial mechanical press fit, with subsequent osseous ingrowth into the prosthesis. Over millions of cycles, bone remodeling can occur around the prosthesis. This dynamic biologic fixation may provide a lifelong bond. Bearing surfaces have historically been metal (cobalt chrome) on plastic (polyethylene). This hard-on-soft bearing has been plagued by wear and osteolysis caused by the biologic reaction to wear debris. Improvements in polyethylene production, in particular cross-linking, have shown significant reduction in wear. Hard-on-hard bearings, that is, metal on metal or ceramic on ceramic, have also shown dramatic reductions in wear. Unique concerns such as elevated metal ion levels, ceramic fracture, and squeaking are under investigation. With stable fixation of the prosthesis and improved wear of the bearing surface, the longevity of current THAs should be improved.

A viable alternative to THA, total hip resurfacing is technically demanding and proper patient selection is crucial. Resurfacing involves removing only the diseased portion of the femoral head thereby conserving proximal femoral bone stock. The femoral component is cemented and coupled to an acetabular component with a metal-on-metal surface bearing.

Guidelines recommend 24 hours of prophylactic perioperative antibiotics and surgical wounds are monitored daily. Patients should receive both mechanical (sequential compression devices and early mobilization) and pharmacologic (aspirin, warfarin, or low-molecular-weight heparin) thromboembolic prophylaxis. Due to lack of consensus, the specific drug and duration of pharmacologic prophylaxis depends on surgeon preference or hospital protocols.

Although there is no universally accepted postoperative THA protocol, certain guidelines do exist. The surgeon determines weight bearing status usually full or partial. Assistive devices are recommended and discontinued at approximately 6 to 12 weeks. Hip precautions are taught to prevent dislocations. Hip abduction pillows may maintain a “safe” position for the hip. Pain control initially involves parenteral narcotic medications with early transition to enteral medications. Regional anesthesia and intraoperative capsular injections may decrease narcotic requirements. Hospital length of stay is typically 2 to 4 days postoperatively. Patients with poor mobility may require extended inpatient rehabilitation. External staples and sutures are removed at 2 weeks. Patients may typically resume their normal lifestyle at 3 months with subtle improvement noted for up to 1 to 2 years.

Efforts to prevent or minimize infections should focus on evidence-based use of perioperative antibiotics, surgical technique, and wound care. Early postoperative infections may be treated with an incision and drainage with component retention. Late infections often require a two-stage explant/replant. Dislocation rates are 1% to 5% lifetime for primary THA and may exceed 10% for revisions. Most dislocations may be managed with urgent reduction and nonoperative measures. Revision surgery is reserved for recurrent instability, particularly in the setting of implant malposition.

Hip Fracture

Treatment algorithms are based on patient age and fracture location (Table 65-2). The main anatomic subgroups are femoral neck and intertrochanteric fractures.

Femoral Neck Fractures

Femoral neck fractures occur between the distal extent of the femoral head articular surface to the most proximal extent of the intertrochanteric region. These intracapsular fractures are either nondisplaced (including valgus impacted patterns) or displaced.

Younger patients The blood supply to the femoral head is retrograde from the medial circumflex to the ascending lateral epiphyseal artery. Any surgical delays increase the risk of avascular necrosis. In this population, femoral neck fractures are treated with closed versus open reduction and internal fixation with multiple lag screws. Postoperative weight bearing is determined by the quality of fracture reduction and fixation. Femoral neck fractures in younger patients are high energy injuries with a 50 to 60% incidence of associated trauma elslewhere.

Older patients In older patients, nondisplaced or stable femoral neck fractures are treated with gentle fracture reduction and multiple lag screws placed percutaneously. This generally low-morbidity procedure has minimal blood loss and patients generally recover rapidly. Displaced fractures have a high incidence of nonunion and avascular necrosis; therefore, internal fixation with preservation of the femoral head is not recommended and hemiarthroplasty (partial hip replacement) is typically performed. Hemiarthroplasties may be cemented or noncemented. It is unclear whether a bipolar (ball within a ball) prosthesis provides any advantage over a unipolar prosthesis to justify the added expense. Total hip arthroplasty may provide improved function and pain relief in physiologically younger patients, but has a higher risk of dislocation.

Postoperatively, immediate mobilization is paramount. Elderly patients have difficulty complying with any weight-bearing restrictions, and nonweight bearing is associated with higher joint reactive forces than weight bearing. No dislocation precautions are necessary with internal fixation. Hemiarthroplasties are inherently stable given the large head size coupled with an intact labrum. However, dislocation precautions are still usually recommended given the high rate of cognitive impairments in this population. Patients should receive routine wound care with external staple or suture removal at 2 weeks. Guidelines recommend chemical and mechanical deep vein thrombosis (DVT) prophylaxis. Any sedating medications should be used judiciously due to the high incidence of delirium. Patients are typically discharged at 3 to 4 days postoperatively and often require prolonged inpatient rehabilitation.

Intertrochanteric Fractures

Intertrochanteric hip fractures occur between the extracapsular distal aspect of the femoral neck to the lesser trochanter. This region of the femur is mainly cancellous bone with an excellent blood supply and therefore a low risk of nonunion. The posteromedial femoral calcar provides stress transfer from the hip to the femoral shaft. Any comminution or displacement in this area leads to an unstable pattern. Intertrochanteric fractures are classified as stable or unstable and require surgical management. Nonoperative treatment may be reserved for patients who are nonambulatory, demented, and/or medically unstable or for isolated nondisplaced and minimally displaced fractures of the greater trochanter. Imaging studies such as a CT scan or MRI are recommended for isolated, minimally displaced fractures of the greater trochanter to ensure there is no extension across the trochanteric area. Isolated lesser trochanteric fractures in the elderly should raise suspicion for a pathologic fracture. Treatment is based on the nature and extent of the pathologic process.

Initially a reduction is attempted using closed techniques but open reductions may be necessary. Internal fixation is achieved with either a sliding hip screw or an intramedullary device. These implants often allow for controlled collapse of the fracture to a stable construct. Intramedullary devices have biomechanical advantages and may be preferred in certain unstable fracture patterns. Higher surgical complication rates have been noted with intramedullary devices. Surgical time and blood loss can vary widely depending on the fracture pattern, body habitus, and bone quality. Outcomes are also dependent on the quality of the fracture reduction and optimal implant choice and position. Primary prosthetic replacement may be an option with certain unstable patterns, tumors, or preexisting arthritis, but is often a much more extensive procedure. Standard antibiotic and DVT prophylaxis are recommended. Wounds are monitored daily with staple or suture removal in 2 weeks. In the absence of complications, hospital length of stay is 3 to 4 days postoperatively. Debilitated patients often require prolonged inpatient rehabilitation.

Anatomy

The knee functions as a weight-bearing hinge; subtle rotation and translation predisposes this joint to injury. The anterior and posterior cruciate ligaments in the sagittal plane and medial and lateral collateral ligaments in the coronal plane provide primary stability. The traversing quadriceps and hamstring muscle groups provide secondary stability. Because the medial and lateral menisci are important in stress distribution, injury or removal of the menisci results in accelerated degeneration of the joint. The knee is divided into medial, lateral, and patellofemoral compartments. With malalignment, one compartment of the knee may receive excessive stress resulting in early degeneration. The synovial lining of the knee capsule produces synovial fluid, which provides lubrication and nutrition to the articular cartilage. The avascular articular cartilage has limited reparative potential in adults.

Total Knee Arthroplasty

During total knee replacement, surgical goals are to restore mechanical alignment, balance the soft tissues, and obtain good fit and fixation of the prosthesis (Table 65-3). The patient is supine with compression devices on the nonoperative leg. Tourniquets are typically used; therefore, blood loss is minimal intraoperatively with postoperative blood loss typically 500 to 1000 mL. Lowering the transfusion threshold to a hemoglobin of <8.5 g/L decreases the rate of allogenic blood transfusions. An anterior midline skin incision followed by a medial parapatellar approach provides access to the deep structures of the knee. The surgeon removes the diseased surfaces of the distal femur and proximal tibia to restore alignment to the knee and make room for the prosthesis. Although press fit designs are available, usually the surgeon cements the appropriate size implants and places a polyethylene liner of appropriate thickness between the metallic femoral and tibial prosthetic components. Controversy exists regarding resurfacing the patella and also retaining or sacrificing the posterior cruciate ligament. Specific approaches, techniques, and implants are highly surgeon dependent. Regional anesthesia (epidural, spinal, or femoral and sciatic nerve blocks) as well as pericapsular knee injections may decrease postoperative pain and narcotic requirements.