CHAPTER OUTLINE
Clinical Evaluation 93
Preoperative Preparation 94
Special Considerations 94
Rheumatoid Arthritis 94
Corticosteroid or Immunosuppressive Treatment 95
Osteonecrosis 95
Post-traumatic Osteoarthritis 95
Preoperative Screening 95
Implant Selection 95
Radiographic Evaluation and Templating 95
Summary 98
Voyages of surgical discovery have the potential to end in disaster, or, to phrase it differently, making the surgery up as you go along is generally not the ideal way to proceed. Careful preoperative planning is the key to successful total hip arthroplasty (THA) and, in essence, each procedure should be performed three times by the surgeon: the first time in one’s head when seeing the patient for the initial consultation, the second while meticulously planning all the details of the surgery preoperatively, and the third when executing the final plan. The focus in this chapter is on the preoperative planning for primary THA.
CLINICAL EVALUATION
Clinical evaluation of the patient should comprise a careful history and physical examination to ensure that the hip is indeed the primary source of the pathologic process. A history of groin pain aggravated by activities such as attempting to put on shoes and socks or getting out of a chair all tend to point to the hip as the source of pain rather than the lower back. A concomitant spinal pathologic process often coexists and can act as a confounder. A diagnostic intra-articular injection of local anesthetic has been used as a discriminator, but strict asepsis is essential for this procedure. Additionally, we have found that the addition of a corticosteroid provides little clinical benefit and also increases the risk of infection with subsequent THA. Clinical examination remains the gold standard, and reproduction or exacerbation of the patient’s symptoms by stressing the affected hip in flexion and attempted internal rotation will usually confirm that the hip is the source of the patient’s symptoms. Patients should, nonetheless, be warned that in the presence of a spinal pathologic process, they may continue to experience regional hip pain even after otherwise successful THA. Additionally, a history of prior lumbar spinal surgery or sciatica should raise concerns regarding possible tethering of the sciatic nerve roots, which may increase the risk of iatrogenic stretch injury to the sciatic nerve during surgery. In this respect, it is important to ensure that patients have realistic expectations regarding the achievable outcomes of THA as per their individual clinical circumstances.
Clinical examination of the hip should include an assessment of abductor muscle strength as well as adductor tightness. On occasion, in the presence of a marked adduction contracture, adductor tenotomy to enhance stability of the total hip construct as well to facilitate subsequent rehabilitation may have to be considered. Palpation of the greater trochanteric bursa region may reveal evidence of greater trochanteric bursitis, which can also be a source of pain in the hip area not only before surgery but also postoperatively. The presence of trochanteric bursitis together with abductor weakness could be indicative of an underlying abductor tear of the insertion into the greater trochanter that may require meticulous reattachment at the time of surgical exposure. Abductor strength should generally not fall below grade 3 (able to abduct against gravity when side-lying). The presence of muscle weakness worse than otherwise clinically expected should alert one to the possibility of an additional concomitant pathologic process such as an abductor tear or proximal myopathy.
Clinical evaluation of leg length discrepancy should include examination of the patient’s spine to check for possible presence of a fixed scoliosis (usually degenerative) ( Fig. 10-1 ). The patient’s perception leg length discrepancy should also be established, because the perception could be at odds with the clinical and radiographic situation. Careful preoperative counseling of the patient is essential to ensure that he or she has realistic expectations regarding what is achievable in this clinical setting.
PREOPERATIVE PREPARATION
Patients should undergo appropriate general physical assessment and workup to ensure that they are indeed medically fit to undergo THA. Given that the average age of patients undergoing THA at my center is 72 years, and that these patients have a mean of three comorbid medical conditions, preoperative internal medicine and/or anesthesia consultation is generally appropriate. Screening for preoperative anemia and discussing with the patient various blood conservation strategies (including preoperative autologous blood donation, use of erythropoietin, or intraoperative blood salvage) is an essential step to reduce allogenic transfusion rates. Recently, allogenic transfusion rates of 39% or higher have been reported, and every effort should be made to reduce this requirement. As yet, the role for routine perioperative administration of β-blockers to reduce cardiac risk has not been firmly established for all patients; however, the use of β-blockers for “high risk” patients is now strongly advised, with consideration being given to modify this approach in patients with a history of severe asthma or a tendency towards congestive heart failure. In addition to the medical preparation, attention should be paid to ensure that patients are both mentally and physically prepared for the surgery. Anxiety and depression can contribute to higher postoperative pain levels and inferior clinical outcomes after surgery. If deemed appropriate, preoperative counseling may be of value for both patient and surgeon. Physical preparation could include a referral to a nutritionist in an attempt to address issues such as obesity and diabetic control, if indicated. A general cardiovascular conditioning program that includes specific preoperative exercises to strengthen musculature around the hip and upper body in preparation for use of assistive devices with mobilization after surgery (together with instruction in the use of the latter) will help facilitate a shortened hospital stay.
SPECIAL CONSIDERATIONS
The cause of the arthritis in the hip also needs to be taken into account because different pathologic processes are associated with certain unique clinical challenges. Ankylosing spondylitis is not infrequently associated with hip arthritis, and patients with this disorder are particularly at risk of heterotopic ossification. Preoperative planning should take into account the need for perioperative irradiation or prophylaxis with indomethacin postoperatively.
Rheumatoid Arthritis
Rheumatoid arthritis is both a polysystemic and polyarticular disease. The preoperative evaluation of a patient with rheumatoid arthritis should include evaluation of issues pertinent to airway access, such as involvement of the patient’s vocal cords or temporomandibular joints. The presence of Sjögren syndrome should be identified because this may have potential implications for increased risk of corneal ulceration if the patient is either heavily sedated or undergoes surgery under general anesthesia. A history of past or current neck pain or stiffness should alert the surgeon to the need for flexion and extension radiographs of the cervical spine to screen for possible atlantoaxial or subaxial instability. Clinical examination of the patient’s upper extremities may also reveal clues as to potential problems with regard to the use of routine assistive devices for mobilization of the patient postoperatively; as such, preoperative evaluation by an occupational therapist and/or physiotherapist may be appropriate. In addition, the patient’s medication may have to be reviewed to determine the potential of anti-inflammatory medication to adversely affect platelet function, which would increase the patient’s risk of bleeding. The use of immunosuppressant agents may place the patient at the increased risk of perioperative infection. Nonetheless, it is essential that patients with rheumatoid arthritis have adequate systemic control of the disease at the time of surgery. This optimal control is usually attainable in consultation with the patient’s attending rheumatologist. In addition, if patients have been on systemic corticosteroids either in the past or currently, this will generally mandate a perioperative boost to the corticosteroid medication to avoid precipitating addisonian crisis.
Corticosteroid or Immunosuppressive Treatment
Patients who have been receiving long-term corticosteroids or other immunosuppressive therapies or who suffer from an underlying immunocompromising disease process may on occasion develop secondary hematogenous septic arthritis. This may be suggested by a sudden onset of increased pain and disability associated with rapid radiographic deterioration of the arthritic changes (with or without an element of diffuse periarticular osteopenia). Clinical suspicion is essential, and preoperative aspiration and/or intraoperative Gram stain plus frozen section (looking for evidence of polymorphonuclear response) should be undertaken where indicated. Preoperative sedimentation rate and C-reactive protein studies are of limited value because these test results would in all likelihood be abnormal owing to the primary disease process; however, if these results show unusually high levels or a major increase as compared with previous tests, then this should add to the level of clinical concern of a secondary septic arthritis exacerbating the underlying primary pathologic process.
Osteonecrosis
Osteonecrosis presents a unique challenge because its associated predisposing causes must be identified prior to surgery and dealt with. Osteonecrosis related to a history of ethanol abuse should alert the surgeon to the potential for the manifestation of withdrawal symptoms (delirium tremens) in the early postoperative period, and associated behavior and/or seizures could result in serious complications, such as dislocation or periprosthetic fracture. Postoperative thiamine supplementation and the administration of “low dose” alcohol such as allowing one beer per day while in the hospital is usually sufficient to avoid the onset of delirium tremens while avoiding issues of heavy sedation and prolonged hospital stay. Counseling on alcohol abuse management is preferably either undertaken well in advance of THA or deferred until after successful surgery and early rehabilitation. Idiopathic osteonecrosis, on the other hand, is associated with increased risk of deep vein thrombosis, whereas sickle cell anemia mandates that the patient be kept well oxygenated and warm both during the surgical procedure and postoperatively to avoid precipitating sickle cell crisis.
Post-traumatic Osteoarthritis
Post-traumatic osteoarthritis may be associated with the presence of post-traumatic deformity and/or the presence of retained hardware. This will require careful preoperative planning in terms of exposure and surgical reconstruction. In addition, if the patient has undergone prior surgery, then workup to include the possibility of underlying infection may be required. Retained hardware can be removed at the time of surgery or as a separate procedure as the first stage of a two-stage reconstruction. The nature and location of the retained hardware may also influence the choice of surgical exposure.
Preoperative Screening
Preoperative screening for potential endogenous sources of hematogenous infection is often underemphasized as an important component of preventing postoperative infection. Preoperative systematic inquiry should include questioning regarding symptoms suggestive of possible urinary tract infection or prostatitis, and clinical examination should include a screening for dental or skin infections.
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