Preoperative Planning and Templating for Primary Hip Arthroplasty
Tad M. Mabry
Key Points
Introduction
Pain relief and restoration of function remain the two primary goals of total hip arthroplasty (THA). The critical first step in achieving these goals is preoperative planning, which must begin as soon as a patient is determined to be a candidate for THA.1 The purpose of this chapter is to describe a method of comprehensive surgical planning that will serve to maximize patient outcomes both in the perioperative period and over the lifetime of the hip reconstruction.
Indications/Contraindications
Comprehensive surgical planning should be performed in advance of all hip reconstructive procedures. The scope of this planning stage must encompass more than simple templating for implant sizes.2 Failure to precisely plan all aspects of the hip reconstruction could result in a number of potentially preventable complications, such as loosening, fracture, instability, and leg length inequality.2–8
Technique: Preoperative Planning
Patient Selection
Great care must be exercised in selecting arthroplasty as the treatment for derangements about the hip. In general, total hip arthroplasty (THA) should be reserved for patients with severe hip pathology who have failed a comprehensive nonoperative treatment program, and who are capable, both physically and cognitively, of recovering from the surgery. In addition to assessment of the patient’s overall health status, several key historical features should be ascertained, including the quality, severity, and location of pain; impact on activities; prior treatments; need for gait aids; and patient perception of limb length.2 Extra-articular pain generators, such as spinal pathology (stenosis, radiculopathy), vascular pathology (vascular claudication), trochanteric bursitis, or stress fracture (pelvis, proximal femur), should be considered during the history-taking process.
Many patients presenting for possible conversion to a primary THA have undergone prior hip surgery, such as osteotomy or internal fixation of fractures. Details of these procedures should be elucidated, including indications for surgery and the presence or absence of postoperative complications such as infection. Whenever possible, it is best to obtain and review old operative notes to better understand any potential alterations to the local anatomy.
Details of the physical examination are found elsewhere in this text; however, this portion of the patient selection process should focus on four main features: confirmation of intra-articular pathology as the pain generator, exclusion of extra-articular pain generators, detailed evaluation of the neurovascular status of the entire limb, and assessment of true and apparent leg length.
Assessment of leg length bears special mention because leg length discrepancy is one of the major causes of patient dissatisfaction following THA.9–11 The surgeon must consider the combination of patient perception and objective measurements when planning the reconstruction to provide appropriate preoperative patient counseling and to best manage leg length discrepancy during surgery.
Radiographic Evaluation
High-quality radiographs of known magnification are essential for both patient selection and templating for THA.6,12-15 Many surgeons utilize a three-view radiographic evaluation, including anteroposterior (AP) views of the pelvis and proximal femur, as well as a true lateral view of the affected hip(s). The AP pelvis allows side-to-side comparison of the hips and radiographic leg length measurement. The AP proximal femur provides complete visualization of the upper femur, which allows more accurate templating of the femoral reconstruction. Where possible, these AP views should be obtained with the hips internally rotated 10 to 15 degrees. This will compensate for femoral neck anteversion and will bring the neck into full profile, thus avoiding underestimation of the patient’s femoral offset. The true lateral view allows visualization of overhanging osteophytes near the anterior or posterior acetabular walls. This view also allows femoral templating in the sagittal plane. A “frog-leg” lateral view of the proximal femur may be used in place of, or as a supplement to, the true lateral view with respect to femoral templating.
Optimization
As was previously noted, preoperative planning should begin as soon as the patient is deemed to be a candidate for THA. The surgeon should consider four separate issues related to medical optimization of the patient before surgery: medical clearance, blood management, infection prevention strategy, and venous thromboembolic (VTE) prophylaxis.
The need for preoperative medical clearance certainly depends on the overall health of the patient. At the time of the original surgical consultation, the patient’s past medical history should be specifically examined for risk factors that would necessitate further preoperative workup, such as cardiovascular disease, pulmonary disease, immunodeficiency, rheumatologic conditions, corticosteroid dependence, bleeding diathesis, hypercoagulability, diabetes mellitus, tobacco dependence, alcohol abuse, or other chronic conditions. Patients should be questioned regarding the details of any prior invasive surgeries and any complications encountered following these procedures. Patients identified as having significant medical risks should be referred to an internal medicine physician for further evaluation and preoperative medical optimization before elective surgical intervention is provided. Aside from benefits to the patient in the preoperative and intraoperative time periods, the results of this medical evaluation will be put to use later in formulating the postoperative care plan.
Blood management is another part of the comprehensive surgical plan and must be considered for each patient individually.16 Blood management is further explored elsewhere in this text. In general terms, there are three areas in which the surgeon may intervene to decrease the need for allogeneic blood transfusion. These areas include increasing the starting hemoglobin, minimizing intraoperative blood loss, and lowering the transfusion trigger to a lower level of hemoglobin/hematocrit.
The first step in this process is evaluation of the patient’s preoperative blood counts. Patients with chronic anemia may benefit from stimulated erythropoiesis to elevate starting hemoglobin during the preoperative period if identified in a timely fashion. Preoperative autologous donation is another method of blood management that must be instituted at the appropriate time. Furthermore, the surgeon must decide in the preoperative period whether to utilize antifibrinolytic medications or blood salvage devices intraoperatively to minimize loss of blood.
Issues related to the mitigation of infection risk must be considered during the preoperative planning stage.17 Areas of active infection remote to the affected joint must be identified and completely treated before elective THA is performed. If there is a possibility of sepsis in the affected joint, this must be identified before conversion to arthroplasty. Antibiotic allergies must be identified so that the appropriate intravenous antibiotic prophylaxis is available in the operating room. Allergies also must be considered if the surgeon intends to utilize prophylactic antibiotics in any cement that may be used as part of the joint reconstruction. Patients taking immunosuppressive drugs (e.g., post transplant, rheumatoid arthritis) may need to have these regimens adjusted in the perioperative period to promote wound healing and minimize the risk of infection.18,19
Interest has arisen in preoperative decolonization regimens aimed at individuals colonized with Staphylococcus aureus.20,21 Patients must be screened for the presence of S. aureus 2 to 4 weeks preoperatively. Colonized patients typically receive 5 days of twice-daily mupirocin ointment applied to the anterior nares. Patients may also be given chlorhexidine skin scrubs during this time period. Patients colonized with methicillin-resistant S. aureus (MRSA) are given intravenous vancomycin rather than a cephalosporin as antibiotic prophylaxis. These regimens have proved very effective in lowering the rate of surgical site infection due to S. aureus.
Finally, the strategy for VTE prophylaxis should be determined preoperatively. All patients are at high risk for VTE following hip arthroplasty.22 There are many postoperative VTE prophylaxis regimens from which to choose, and the particular method should be selected after the risks of bleeding versus the risks of clotting are considered for each individual patient.23,24 Risk factors that may further elevate the postoperative clotting risk must be ascertained before surgery. Some of the more common diagnoses that could add to the risk of postoperative VTE in the hip arthroplasty population include malignancy (active or occult), prior VTE, estrogen-containing medications, obesity, and thrombophilia (inherited or acquired).22
Each of these issues related to medical optimization (medical clearance, blood management, infection mitigation, and VTE prophylaxis) must be taken into account during the preoperative planning stage to maximize patient outcomes.
Templating
Templating the hip reconstruction serves multiple important purposes in the preoperative planning stage of total hip arthroplasty. First, careful templating will improve the surgeon’s ability to restore favorable biomechanics to the joint, including leg length and offset. Second, templating will allow the surgeon to determine which implants will be required to carry out the reconstruction. Implant selection on both sides of the joint is determined by local anatomy, periarticular bone quality, and surgeon experience. In some cases, special devices may have to be made available that are not standard at the surgeon’s hospital. Third, templating allows the surgeon to take note of osseous deformity and local landmarks that will facilitate appropriate component placement. Proper implant placement will benefit the patient in both the short term (e.g., decreased dislocation risk) and the long term (e.g., wear of the bearing surface) following THA. Finally, the templating process allows the surgeon to think in three dimensions and becomes a rehearsal of the reconstruction to be performed. Following is a stepwise approach to templating for primary THA.
Step 1: Determine the Magnification
It is critical to first determine the magnification of the radiographs to be templated, because all subsequent steps are based on measurements that have been appropriately corrected.12 This is most often done by utilizing some type of external magnification marker at the time of radiographic exposure.12,13
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