3. Adult Reconstruction (Hip & Knee) MCQs

DISCUSSION: This complication is best addressed with either a single-stage or two-stage total knee arthroplasty. A recent report suggests that a single-stage arthroplasty can be effective, although many surgeons would perform a two-stage procedure with an articulating or static spacer. Arthroscopic debridement would be non-effective, especially given 4 weeks of symptoms. Resection arthroplasty without a spacer would leave an unstable and poorly functioning extremity. Knee fusion should be used as a salvage procedure.

Yang and Weiland, from New York studied subsidence after trapezium excision and interposition arthroplasty. They compared preoperative and postoperative x-rays at rest as well as with maximal lateral key pinch stress. Lateral keypinch stress causes a large amount of axial compressive force through the CMC joint. They also compared preoperative and postoperative functional measurements, including key pinch strength, tipto-tip pinch strength, grip strength, and thumb ROM. Their findings were that postoperatively the first metacarpal subsided 21% at rest (p=0.001). and it subsided another 10.5% during maximal lateral key pinch. Even with this degree of subsidence, the patients experienced increases in pinch strength and grip strength. Also, all patients except for one who had bony impingement reported that they were subjectively much better and more functional.Lin et. al. also studied trapezium excision and interposition arthroplasty and found no significant differences between results in patients with varying degrees of subsidence. Thus, subsidence does not affect the results of interposition arthroplasty for basal thumb arthritis.back to this question next question

DISCUSSION: Using press-fit tibial stems during a hybrid revision total knee arthroplasty is associated with a 3% to 5% incidence of intraoperative tibial shaft fracture. Diaphyseal fixation of press-fit stems has the advantage of setting component alignment, dispersing forces on the proximal tibia, and offers excellent clinical results. The disadvantages include proximal and distal tibia anatomic mismatch and tibial shaft fracture. Cipriano and associates reported a tibial shaft fracture incidence of 4.9% in a series of 420 consecutive knee revisions.

DISCUSSION: Noninvasive cardiac testing is recommended in the presence of the three or more of the following risk factors in a sedentary patient: history of coronary artery disease or myocardial infarction, history of heart failure, prior cerebrovascular accident, and diabetes mellitus or chronic renal disease. Preoperative stress testing is not recommended if patients can perform moderate activities such as climbing a flight of stairs.REFERENCES: Bushnell BD, Horton JK, McDonald MF, et al: Perioperative medical comorbidities in the orthopaedic patient. J Am Acad Orthop Surg 2008;16:216-227.Auerback A, Goldman L: Assessing and reducing the cardiac risk of noncardiac surgery. Circulation 2006;113:1361-1376.Fischgrund JS (ed): Orthopaedic Knowledge Update 9. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2008, pp 105-113.

DISCUSSIONStiffness following TKA is a disabling complication. One option involves MUA, a valuable technique with which to increase range of motion after TKA for patients with stiff knees. A systematic review of the literature was performed to identify studies that reported the clinical outcomes and measured range of motion for patients undergoing MUA. Fourteen studies (913 patients) reported range of motion results following MUA at up to 10-year followup. The review demonstrated that MUA for a stiff primary TKA is an efficacious procedure to restore range of motion, and it carries a low complication rate. Early gains in motion werereported to be maintained in the long term. A second review systematically evaluated the outcomes of 4 treatments for arthrofibrosis that develops subsequent to TKA (MUA, arthroscopic debridement, open surgical release, and revision TKA). This study showed that there were no significant differences in the Knee Society Score of the 4 treatment modalities. Although open surgical release resulted in the greatest increase in range of motion, there were methodological study limitations because the majority of the papers were case series, which decreased the quality of the evidence. Response 1 is correct because the TKA appears appropriately sized and is well aligned. Responses 2 and 3 are incorrect, considering the early time frame (8 weeks) from initial surgery. Although the patella is unresurfaced in the radiographs, there is no indication for revision TKA (even secondary patellar resurfacing) at this early juncture.

The patient has symptoms of synovitis that are most likely the result of the release of particles from the tibial polyethylene. While observation may be warranted in a completely asymptomatic knee, some intervention is indicated for this patient as there is clear radiographic evidence of lysis in both the tibia and femur. The decision about the extent of the revision should be made at the time of surgery. Surgical exploration with revision or exchange based on the findings is the most appropriate approach.

Controversy persists over what exactly is the best approach to managing patients with metal-on-metal (MOM) hip arthroplasties. All patients with painful MOM hip arthroplasties should be examined for fixation loosening, wear/osteolysis, and infection. It is recommended to obtain serum trace element levels. If the levels are high, cross-sectional imaging should be obtained to determine whether any pseudotumor or tissue necrosis is present around the hip arthroplasty. Adverse tissue reaction has been identified to occur around MOM hip arthroplasties. The predominant histologic feature is tissue necrosis with infiltration of lymphocytes and plasma cells.

DISCUSSION: In a relatively young patient who is an avid tennis player, the treatment of choice is a joint preserving procedure. The radiographs reveal varus alignment with loading of the medial compartment. After all nonsurgical management options have been used, the best treatment option is a medial opening wedge osteotomy. A lateral closing wedge osteotomy of the proximal tibia is also a reasonable option, but it is not one of the choices. A unicompartmental arthroplasty or a total knee arthroplasty would place significant restrictions in this patient. A unispacer may be a temporizing procedure but is controversial and without substantial data in the literature. The knee arthroscopy will not address the medial compartment osteoarthritis.

Mechanical loosening of the hip is best revealed by serial radiographs of the prosthetic joint. None of the other methods of evaluation is considered reliable in diagnosing mechanical loosening.

Survivorship is similar in the two groups. In a recent study, mobile-bearing TKAs showed a slightly higher maximum flexion than the total condylar fixed-bearing-type designs (112 degrees versus 108 degrees with no difference in recovery rate). Using a fixed-bearing or a mobile-bearing design did not seem to influence the recovery rate in early results after knee arthroplasty. Mobile-bearing arthroplasties are suggested, in theory, to offer a reduction in polyethylene wear; however, clinical studies have not yet proven this. Recovery rates have yet to be statistically seen as improved with either method. Differences in strength have not been shown.

The arrows in the radiograph point to circumferential radiolucencies that strongly support the diagnosis of septic loosening. Radiolucent lines that occur in such a short time are also typical of an infection.

The radiograph reveals destruction of the femoral head with loss of the articular cartilage. These findings are consistent with an infected hip, and aspiration will confirm the diagnosis. Although the patient could have advanced osteonecrosis, typically the cartilage interval is maintained and such destruction is rarely associated with osteonecrosis.

The radiograph and intraoperative photograph show osteonecrosis with near complete head loss/collapse. A stemmed implant is more appropriate in this patient because there is very little bone to support a resurfacing implant. In a younger patient, a glenoid implant should be delayed as long as possible because of the eventual need for revision secondary to glenoid loosening and wear, especially in a young active male. The hemiarthroplasty may be converted to a total shoulder arthroplasty in the future.

DISCUSSION: Billote and associates compared patients with normal baseline hemoglobin levels who did and did not donate autologous blood prior to total hip arthroplasty. No patients received allogeneic blood perioperatively, and the autologous donors had significantly lower hemoglobin levels at the time of surgery and in the recovery room. Of the autologous donors, 69% received an autologous transfusion. The authors concluded that autologous donation was unnecessary in patients undergoing primary total hip arthroplasty who had a normal hemoglobin.

DISCUSSION: Stems are available for cemented and press-fit implantation. To be effective, press-fit stems should engage the diaphysis. They also assist in obtaining correct limb alignment. Short metaphyseal-engaging stems are associated with failure rates that range between 16% and 29%. Cemented stems may be shorter than press-fit stems, because they do not have to engage the diaphysis. Short, fully cemented stems offer the advantage of metaphyseal fixation. Hybrid stem fixation makes use of the metaphysis for cement fixation with metaphyseal cones or sleeves and diaphyseal-engaging press-fit stems.

Any patient who is severely symptomatic this quickly after surgery must be evaluated for infection. Loosening is also a possible cause, but infection must be ruled out. Bone scans are not helpful at this early postoperative stage. Normal laboratory values argue strongly against infection, but when abnormal, need to be supplemented with a hip aspiration. Aspiration remains the most selective and sensitive measure, especially when linked to a WBC count of the synovial tissues in the joint. There is no indication for an antibiotic trial because it may make future culture sensitivity more difficult.

DISCUSSION: Astion and associates analyzed 23 acetabular components, out of a total of 173 implanted, that had failed because of either migration or severe osteolysis. The radiographic appearance of osteolysis was positively associated with the duration that the implant had been in situ. The prevalence of osteolysis was also significantly greater in acetabular components with an outer diameter of 55 mm or less (a polyethylene thickness of 8.5 mm or less). Thirteen of the 23 components were revised at a mean of 70 months after the index operation. Examination of the retrieved acetabular components revealed extensive polyethylene damage on the articular and back surfaces of the liners. Cracks in the polyethylene rim of the liner and deformation of the antirotation notch in the polyethylene rim were common findings. The density of the polyethylene was greater than expected, and more particles than anticipated had not fused with the surrounding polyethylene. Factors related to both the design and the material contributed to the failure of these porous-coated anatomic acetabular components.

DISCUSSION: The patient has hypertrophic arthritis, which is a strong risk factor for heterotopic bone formation. The remaining complications are possible but do not have the same significant risks. REFERENCES: Goel A, Sharp DJ: Heterotopic bone formation after hip replacement: The influence of the type of osteoarthritis. J Bone Joint Surg Br 1991;73:255-257. Nollen JG, van Douveren FQ: Ectopic ossification in hip arthroplasty: A retrospective study of predisposing factors in 637 cases. Acta Orthop Scand 1993;64:185-187.

Tannenbaum and associates found that patients who had a joint replacement after an organ transplantation had a rate of infection of 19%. They retrospectively reviewed the results of 35 joint (hip or knee) replacements in 19 patients who had an organ transplant. An infection developed around the implant in five patients who had undergone the joint replacement after a transplantation.

DISCUSSIONThigh swelling, bloody drainage, and the persistent need for postsurgical transfusion of PRBCs to maintain adequate hemoglobin and hematocrit levels indicates the presence of a substantial hematoma. Factors contributing to hematoma formation include the large dead space associated with a large soft-tissue pseudotumor, use of postsurgical pharmacologic DVT prophylaxis, higher American Society of Anesthesiologists (ASA) index, and substantial intrasurgical blood loss. Urgent surgical treatment of a postsurgical hematoma with persistent wound drainage is indicated to minimize risk for infection of the prosthetic components. Postsurgical hematoma may also be culture positive or represent early postsurgical infection. Irrigation and debridement should include exchange of the head and liner to provide access for debridement of the modular implant interfaces.This patient has an infected revision THA with an open wound nearly 3 weeks after surgery. Irrigation and debridement with wound closure is appropriate for treatment of acute postsurgical infections. However, a high failure rate has been associated with this procedure and retention of the components, particularly in the setting of Staphylococcus aureus infection. A large, relatively poorly vascularized wound also increases risk for recurrent infection with retention of components. Treatment at this point to control infection necessitates removal of the prosthetic components. Because of the massive segmental proximal femoral bone loss, excision arthroplasty would result in a markedly shortened flail limb and considerable functional impairment. Removal of the components and insertion of an antibiotic cement spacer would allow wound closure and control of infection with the option of later second-stage reconstruction.