3. Adult Reconstruction (Hip & Knee) MCQs

DISCUSSIONDistal femoral osteotomy is the preferred surgical treatment for this young patient. A varus-producing proximal tibial osteotomy is not indicated with valgus deformity and lateral femoral hypoplasia. Osteotomy on the tibial side would result in obliquity of the joint line and improper loading. Lateral unicompartmental arthroplasty or TKA are both less appropriate for this patient, who will be placing high demands on his knee; these demands will pose high risk for premature failure of an artificial knee implant and could necessitate revision surgery.

DISCUSSION: Figure 1 reveals an external rotation deformity of the right lower extremity. This deformity can have numerous causes, including extra-articular deformity. Figure 2 reveals a loose, subsided femoral component. Femoral stems typically subside into retroversion due to proximal femoral biomechanics, which cause a compensatory external rotation deformity. The combined findings from both images suggest an external rotation deformity most likely related to subsidence into retroversion.

DISCUSSIONBranches of the lateral femoral circumflex artery arise from the inferior aspect of the anterior hip capsule. They can be injured when removing the anterior capsule from any approach. The inferior gluteal artery supplies the gluteus maximus. The medial femoral circumflex artery enters the hip joint along the path of the obturator externus tendon. The femoral artery crosses the anterior hip joint in the superior-to-inferior direction and is located just medial to the hip joint.

DISCUSSION: Patients require prophylaxis for heterotopic bone after resection to prevent recurrence. The optimal management has been found to be a dose of 700 cGy in one dose delivered either pre- or postoperatively. A dose of 2,000 to 3,000 cGy is considered excessive. Radiation therapy consisting of 1,000 cGy in five doses is an acceptable prophylaxis; however, it will require an extended hospital stay of 3 to 4 days and is more problematic for the patient who must be transported for radiation therapy for 5 days. A dose of 400 cGy is not as effective in prophylaxis for heterotopic bone formation. REFERENCES: Healy WL, Lo TC, DeSimone AA, Rask B, Pfeifer BA: Single-dose irradiation for the prevention of heterotopic ossification after total hip arthroplasty: A comparison of doses of five hundred and fifty and seven hundred centigray. J Bone Joint Surg Am 1995;77:590-595. Pelligrini VD Jr, Gregoritch SJ: Preoperative irradiation for the prevention of heterotopic ossification following total hip arthroplasty. J Bone Joint Surg Am 1996;78:870-881. Pelligrini VD Jr, Konski AA, Gastel JA, Rubin P, Evarts CM: Prevention of heterotopic ossification with irradiation after total hip arthroplasty: Radiation therapy with a single dose of eight hundred centigray administered to a limited field. J Bone Joint Surg Am 1992;74:186-200.

(1001) Q1-1308:In a patient with a previous compression hip screw in place at the time of total hip arthroplasty, what precautionary measures should be undertaken after hardware removal to prevent a periprosthetic fracture:

The management of patients with proximal femoral deformity can be difficult. Appropriate implant selection and preoperative templating are critical. In this patient, it would be difficult to avoid increasing the combined offset by too much, which could contribute to the overtensioning of the soft tissues and trochanteric pain. By medializing the acetabular component (decreasing the combined offset), using a low offset femoral component or a cemented component placed more valgus (decreasing the combined offset), and making a longer neck cut (to avoid shortening of the lower extremity), restoration of the patient’s native offset and leg length can be achieved.

The incidence of femoral fracture in primary cementless total hip arthroplasty ranges from 1.5% to 27.8%. It is imperative that the implant and fracture are stable both intraoperatively and postoperatively. Cerclage wiring or cerclage cabling is the current recommended treatment for nondisplaced calcar fractures and minimally displaced proximal fractures. Berend and associates reviewed the results of 58 total hips in 55 patients with intraoperative calcar fracture managed with single or multiple cerclage wires or cables and immediate full weight bearing. Follow-up averaged 7.5 years, and there were no revisions of the femoral component. No patients had severe thigh pain.

Gamma irradiation produces free radicals. Although these free radicals can form cross-links with other polyethylene chains, the free radicals can also form a bond with oxygen, resulting in early oxidation. Gamma irradiation in air produces the highest risk for oxidized polyethylene, resulting in the highest risk for wear, delamination, and subsequent osteolysis. This patient demonstrates severe periarticular osteolysis. When she is asymptomatic, this suggests the acetabular and femoral components remain well fixed to the bone. Consequently, she can be treated by removing the wear generator (polyethylene exchange), along with bone grafting of the osteolytic defect. Considering the extensive amount of osteolysis, indefinite observation would not be appropriate. A foot drop develops 2 days after surgery. As a result, it can be assumed that the nerve was not injured directly during the surgical procedure. Although MRI or CT may be indicated to identify an evolving hematoma, the immediate concern is to minimize pressure on the sciatic nerve. Tension on the nerve can be reduced by flexing the surgical knee and positioning the bed flat.

Thromboembolic disease can occur in up to 58% of unprotected patients and up to 20% of protected patients depending on the type of prophylaxis used, even though most thrombi are small and have little clinical consequence. The primary goal of prophylaxis is to prevent symptomatic deep venous thrombosis and fatal pulmonary emboli. Dislocation has been reported in up to 10% of primary cases, but generally acceptable rates of less than 5% are the norm. Component loosening following primary total hip arthroplasty is rare prior to a 10-year follow-up, and 90% to 95% of patients should reach the 10-year follow-up without the need for revision for any reason. Metal hypersensitivity is unusual, and nickel found in cobalt-chromium alloys is the most common offending agent. Infection of primary total hip arthroplasty is less than 1%.

The lesser tuberosity should be placed at position A, and the biceps tendon at positionB. One of the most common errors during proximal humeral arthroplasty is the use of the lateral keel of the prosthesis as the landmark, around which the tuberosities are reconstructed. If this is done, the anterior soft tissue/bone element is stretched, while the posterior soft tissue/bone element is lax, with a resultant loss of external rotation of the arm. The biceps should be used as the proper landmark for tuberosity reconstruction and in its absence, the anterior aspect of the prosthesis, where the bicipital groove would have been, should be used as the central juncture of tuberosity reconstruction. The upper border of the pectoralis is best used to gauge appropriate height but knowing that the biceps tendon runs directly underneath the tendon insertion can also aid in estimating the proper location.

This patient presents with a pseudotumor likely attributable to local tissue reaction resulting from either articular metal wear debris and/or corrosion and fretting of the trunnion. The trunnion is a more likely source of the problem for a number of reasons: good position of metal articulation, increased trunnion corrosion and fretting associated with large-head THA, and markedly increased cobalt levels compared to chromium levels. Infection is very unlikely in the setting of normal ESR and CRP findings. MR imaging findings are consistent with pseudotumor and not iliopsoas tendonitis or trochanteric bursitis.

The magnitudes of out-of-plane loads on a total hip replacement during activities of daily living can be substantial. Bergmann and associates studied these forces about two instrumented hip prostheses. They noted that the torsional moment about the hip during stair climbing is twice as high as during slow walking and that similar moments are generated during slow jogging. Higher loads were noted when the patients stumbled without falling. They also noted that the torsional moments observed in vivo were close to or even exceeded the experimentally determined limits of the torsional strength of implant fixations.

Figure 1 is the radiograph of a 73-year-old woman who had a right hip arthroplasty one year prior. Her BMI is 48. Postoperative radiographs at 6 weeks showed early stem subsidence of 4 mm compared with intraoperative radiographs. The current radiographic findings likely resulted from theA. spinal fusion.B. BMI and implant size.C. mismatch between the metaphysis and diaphysis.D. modular neck prosthesis.

DISCUSSION: This approach is criticized for the episodic limp associated with the muscle detachment and reattachment. Classically, two thirds of the gluteus medius is detached as a sleeve with the vastus lateralis. This exposes the gluteus minimus and the ligament of Bigelow. These must also be detached to allow dislocation of the hip and osteotomy of the femoral neck. The rectus femoris lies medially and anteriorly and does not need to be addressed.

DISCUSSION: Hip fusion provides successful long-term results (20 to 30 years). The usual mode of failure is symptomatic arthrosis of the lower back, contralateral hip, or the ipsilateral knee. Disabling low back pain is the best indication for conversion and responds well to the procedure. Degenerative changes in the other joints do not respond as well and frequently require replacement arthroplasty. Restoration of limb length is not predictable after conversion to hip replacement.

DISCUSSION: The MSIS definition of periprosthetic joint infection was updated in 2014 with two major and six minor criteria. The current MSIS minor criteria are 1) an elevated ESR (more than 30 mm/hr) and CRP level (more than 10 mg/L), 2) an elevated synovial WBC count (more than 3,000 cells/microliter), 3) an elevated synovial fluid polymorphonuclear count (more than 80%), 4) a positive histological analysis of periprosthetic tissue, and 5) a single positive culture.

DISCUSSION: Sternoclavicular joint sepsis is a rare condition that is most often restricted to patients who are immunocompromised, diabetic, or IV drug abusers. Examination commonly reveals a tender, painful, and possibly swollen sternoclavicular joint. If suspicion remains high following a thorough history, physical examination, radiographs, and routine blood tests, joint aspiration should be performed prior to incision and drainage or administration of antibiotics.

DISCUSSION: Instability following unconstrained elbow arthroplasty occurs in 10% of patients. Subluxation is twice as common as frank dislocation; however, only 20% of these patients undergo revision. Instability following unconstrained elbow arthroplasty can be caused by component malposition or ligament insufficiency.

DISCUSSIONThe lowest reported rates of osteolysis involving cemented TKAs are associated with monolithic tibial components. Modular components and cemented metal-backed patella components are associated with a high prevalence of backside tibial insert wear and osteolysis.

Chronic opioid consumption prior to total joint arthroplasty has been associated with increased pain after surgery, increased opioid requirements, a slower recovery and longer hospital stay, and higher 90-day postoperative complications compared with patients not on chronic opioids preoperatively. The recommendation based on the provided literature is to decrease the patient's narcotic use prior to surgery.