Hip Fracture

Hemiarthroplasty

Douglas E. Padgett

Indications

1. Displaced femoral neck fractures not appropriate for reduction and internal fixation

2. Displaced low femoral neck fractures (“base of neck”) not appropriate for reduction and internal fixation

Contraindications

1. Proximal femoral fracture in the setting of active sepsis: either acute osteomyelitis or acute supparative arthritis (absolute)

2. Proximal femoral fracture in the setting of neuropathic joint (relative)

3. Proximal femoral fracture in patients unable or unwilling to comply with postoperative protocols that minimize the risk of hip dislocation (relative)

4. Decubitus wounds contiguous with the planned surgical incision (relative)

Preoperative Preparation

Fractures of the proximal femur are a sentinel event in the life of any patient. Femoral neck fractures in patients under the age of 50 usually result either from high-energy trauma or in association with significant metabolic bone disease that has weakened the femur. Femoral neck fractures in the elderly are usually not high-energy injuries, but frequently occur in patients with significant medical cormorbidities. Elderly patients with these fractures are at a significant risk for morbidity and/or mortality in the perioperative period. These facts should always be remembered when treating a patient with a proximal femoral fracture.

1. Complete history and physical examination

2. Appropriate medical and anesthetic evaluation

3. Document preoperative neurovascular status.

4. Examine and document the status of the skin’s integrity since many of the patients are at risk for postoperative decubitus ulcers.

5. Radiographs including anteroposterior (AP) of the pelvis and lateral of the proximal femur. Occult fractures may not be apparent on plain radiographs and require either magnetic resonance imaging (MRI) or bone scintingraphy to diagnose a fracture.

6. The preoperative radiographs should be assessed in conjunction with the appropriate hip prosthetic templates to determine approximate component sizes. Preoperative templating should be performed to determine:

a. Level of femoral neck resection

b. Femoral component size

c. Distances from fixed points on the femur to the center of hip rotation in order to help optimize postoperative limb length

d. If the femoral implant adequately reconstructs femoral offset and proper hip mechanics

e. Approximate size of bipolar head to be utilized. With current modular systems, the size of the bipolar cup determines the femoral head size (22, 26, or 28 mm) that allows adequate polyethylene thickness.

Special Instruments, Position, and Anesthesia

1. The patient is placed in the lateral decubitus position with the affected hip upward. Adequate padding of the axilla is necessary to avoid injury to the brachial plexus. While the patient must be secure on the operating room table, excessive tightening of pelvic posts should be avoided, since this can compromise the neurovascular status of the “down-leg” (Fig. 22–1).

2. All pressure points should be padded.

3. The procedure can be done with general, epidural, or long-acting spinal anesthesia. There is some evidence that epidural anesthesia decreases the risk of deep-vein thrombosis as well as decreasing blood loss during total hip arthroplasty (presumably by a reduction in pelvic venous pressure). In addition, postoperative analgesia may be administered via the epidural catheter.

4. Instruments required for hemiarthroplasty include self-retaining retractors, straight and bent Hohman-type retractors, a femoral neck elevator to facilitate exposure of the proximal femur, and power saws. In addition, the specific instruments, broaches, and trial components unique to the prosthesis to be implanted should be available.

5. Consider using enclosed helmets and body exhausts, which may help minimize the risk of perioperative sepsis.

6. Intravenous antibiotics appropriate for the hospital’s bacterial flora should be administered prior to tourniquet inflation and continued for at least 24 h after surgery.

Tips and Pearls

1. Accurate re-establishment of the preoperative leg length is difficult to accomplish in the setting of a displaced femoral neck fracture. On occasion, the approximate leg length can be estimated based upon the opposite extremity.

2. Due to the edema associated with an acute hip fracture, some of the tissue planes adjacent to the posterior capsule can be difficult to identify. If necessary, consider taking down the posterior capsule and short external rotator tendons as one large flap.

3. The use of a ligamentum teres knife (a curved blade) is useful in aiding extraction of the femoral head from the acetabulum.

4. If the bone is extremely osteoporotic, consider using only broaches for femoral preparation (to compact the cancellous bone) rather than a combination of broaching and reaming (which tends to remove the cancellous bone bed).

5. The size of the bipolar head is determined by feel. Consider measuring the diameter of the excised femoral head. This serves as a rough guide for the appropriate size of the bipolar head. The trial bipolar head should fit easily into the acetabular socket. However, there should be a slight suction fit of the trial component.

6. Optimizing stability with bipolar hemiarthroplasty is essential. In situations where there is a large fixed flexion contracture with adduction, altering surgical approach to an anterior or anterolateral (Hardinge) approach can be considered.

7. The use of cement for femoral component fixation is recommended for treatment of the majority of these fractures.

What To Avoid

1. Because of the problems associated with infection, great care is taken to minimize this complication. Operating room traffic should be minimized, and preoperative antibiotics administered.

2. Avoid “overstuffing” the acetabulum socket with an oversized bipolar component. This may be a source of postoperative groin pain or increase the risk of component dislocation in some patients.

3. Avoid compromising cement technique in order to “rush through” the case. An adequate cement mantel is critical for success in both total hip arthroplasty as well as bipolar hemiarthroplasty. Adhere to appropriate methods of canal preparation and cement pressurization during surgery.

4. Avoid excessive broaching or reaming of the femur especially when cement fixation of the femoral component is planned. Over-zealous removal of cancellous bone will weaken the bone-cement interface and may predispose to early component loosening. Femoral preparation should be performed in a controlled methodical fashion.

5. Do not excessively antevert or retrovert the femoral component. Careful assessment of the femur’s inherent torsion is an excellent indicator of amount of anteversion with which to insert the stem.

6. Avoid a varus or retroverted alignment of the femoral component.

Postoperative Care Issues

1. While not mandatory a suction type drain can be used and normally safely discontinued the morning after surgery.

2. Thromboembolic precautions are recommended. Options include intraoperative heparin, aspirin, warfarin, low-molecular weight heparin, and intermittent pneumatic compression.

3. The use of a hip abduction splint or hip abduction slings attached to overhead suspension is useful to avoid untoward motions of the limb, which may compromise hip stability Many patients undergoing hip hemiarthroplasty are elderly and have a tendency for confusion and disorientation, which increases the risk of dislocation. Consider using a knee immobilizer to help minimize the risk of dislocation, as it maintains the knee in an extended position, thereby making hip flexion difficult. Thus, the chance that the hip will be placed in a hyper-flexed position, which predisposes it to dislocation, is reduced.

4. Weight-bearing status is dependent upon fixation, integrity of the trochanter, as well as the presence of any other associated fractures. This information must be conveyed to the physical therapy staff and nursing staff. Full weight bearing is most common with cement fixation.

5. Precautions such as avoiding excessive hip flexion and/or hip rotation should be reviewed with the patient.