3. Adult Reconstruction (Hip & Knee) MCQs

DISCUSSION: The radiograph reveals developmental dysplasia of both hips. The patient has classic anterolateral undercoverage of the femoral head on the right side as demonstrated by a high acetabular index (measured at 27 degrees). Anterior undercoverage can be determined by drawing the marking for the anterior wall that fails to overlap the femoral head in this patient. Currently in North America, the most accepted surgical management for symptomatic dysplasia of the hip with good joint space is a Bernese (Ganz) periacetabular osteotomy. Surgical dislocation of the hip and femoroacetabular osteoplasty may be considered for patients with symptomatic femoroacetabular impingement of the hip.

This topic is listed in Appendix D of the Code of Ethics for Orthopaedic Surgeons/American Academy of Orthopaedic Surgeons under sections III B and C. III. Conflicts of Interest B. Where there are financial interests involved in the ownership of a pharmacy, rehabilitation center, imaging equipment, surgery center, or health care facility where the orthopaedic surgeon’s financial interest is not immediately obvious, the orthopaedic surgeon must disclose that financial interest to the patient and to colleagues. C. When an orthopaedic surgeon receives anything of value, including royalties, from a manufacturer, the orthopaedic surgeon must disclose this fact to the patient and to colleagues. It is unethical for an orthopaedic surgeon to receive compensation (excluding royalties) from a manufacturer for using a particular device or medication. Reimbursement for administrative costs in conducting or participating in a scientifically sound research trial is acceptable.

DISCUSSION: Type I fractures are trochanteric fractures usually secondary to osteolysis. Type II fractures are located around the stem. Type III fractures are distal to the stem. If the fracture and prosthesis are stable, the fracture can be treated nonsurgically. If the fracture is unstable, the stability of the prosthesis should be assessed. If the prosthesis is unstable (type IIB), treatment should consist of revision to a long stem prosthesis that bypasses the fracture by two cortical diameters. If, as in this patient, the prosthesis is not loose (type IIA), open reduction and internal fixation is the appropriate option. Proximal femoral allograft is appropriate for type IIIC fractures in which the proximal bone is significantly compromised and the femoral component is loose.

DISCUSSION: This patient's history and physical findings are concerning for deep infection. Inflammatory markers, including ESR and CRP, should be obtained first. If the levels are elevated, knee aspiration should be performed for the synovial cell count and culture. A bone scan is not indicated in an initial investigation for deep infection; it is rarely helpful and is not cost-effective. CT to assess implant rotation is an appropriate investigation for knee pain when the clinical scenario is not suspicious for a deep infection and when infection has been excluded.

DISCUSSIONIn 2014, the MSIS published its revised PJI definition for clinical and research use. If 1 of 2 major criterions is met (phenotypically identical organisms obtained from 2 separate cultures or a draining sinus tract), then PJI is diagnosed. Alternatively, if 3 of 5 minor criterions are met, PJI is diagnosed.

DISCUSSION: THA has proven durable and reliable for pain relief and improving function for patients with end-stage arthritis. Appropriate bearing selection is critical to minimize wear and hip complications. A metal-on-metal articulation is associated with excellent wear rates in vitro. However, local soft-tissue reactions, pseudotumors, and potential systemic reactions including renal failure, cardiomyopathy, carcinogenesis, and potential teratogenesis with potential transfer of metal ions across the placental barrier make metal-on-metal bearings less desirable and relatively contraindicated for younger women of child-bearing age.

DISCUSSION: A variety of methodologies have been used to decrease the need for homologous blood transfusions following THA. Some of the effective strategies include preoperative donation of autologous units, intraoperative salvage and recycling, preoperative injection of erythropoietin, and regional anesthesia. Cementless fixation and use of wound drains have been shown to increase the blood loss with THA. REFERENCES: Huo MH, Paly WL, Keggi KJ: Effect of preoperative autologous blood donation and intraoperative and postoperative blood recovery on homologous blood transfusion requirement in cementless total hip replacement operation. J Am Coll Surg 1995;180:561-567. Bierbaum BE, Callaghan JJ, Galante JO, Rubash HE, Tooms RE, Welch RB: An analysis of blood management in patients having a total hip or knee arthroplasty. J Bone Joint Surg Am 1999;81:2-10. Ritter MA, Keating EM, Faris PM: Closed wound drainage in total hip or total knee replacement: A prospective, randomized study. J Bone Joint Surg Am 1994;76:35-38.

DISCUSSION: This patient has severe, uncorrectable varus deformity and pain from end-stage osteoarthritis secondary to prior adolescent tibia vara. Although he is young to consider arthroplasty, this option is likely to give him the most functional limb, compared with arthrodesis with a long antegrade nail. During arthroplasty surgery, his knee will likely require extensive medial release to achieve anatomic limb alignment. Standard components in total knee arthroplasty likely would result in lateral instability, so this option is not the best answer. The best choice is total knee arthroplasty with a constrained device, which adds constraint to the knee to provide balance.

DISCUSSION: The radiograph reveals complete loss of joint space with particulate metal debris consistent with total polyethylene failure and metal-on-metal articulation. The components appear to be well fixed and minimal osteolysis is evident.

DISCUSSION: Hyaluronate is a naturally occurring compound that is the backbone of the central core of the proteoglycan aggregate. Hyaluronate forms the base or central core of the aggregate on which a link protein binds a protein core.

The patient is an African American male prisoner with symptomatic right hip osteoarthritis. When formulating a treatment plan, it is important to understand the role of physician implicit bias in delivery of care and in creating disparities inhealthcare delivery.Physician bias, prejudice, discrimination, and clinical uncertainty are all factors that contribute to health care disparities in the United States. Implicit and explicit attitudes are cognitive traits that influence physician delivery of care, and sometimes these attitudes do not perfectly correspond. It is important for a physician to understand that his implicit attitudes about a patient may unintentionally influence care despite his explicit attitudes. Physicians should be aware of their implicit biases in order to provide more effective decision-making and quality of care.Stone et al. write about the issue of culturally competent delivery of care and the avoidance of unconscious bias in medical decision making. They argue that because unconscious stereotypes and prejudices can trigger biased medical decisions against specific groups, leading to the creation of differential diagnoses, disparities in treatment, and causing minorities to feel uncomfortable with seeking or complying with treatment plans. The authors suggest the integration of cultural competency training into medical education in order to help understand the perspective of the minority group patient.Sabin et. al. compared the implicit and explicit biases of physicians with respect to race, gender, and age. They found that medical doctors showed an implicit bias of preferentially caring for White Americans relative to Black Americans, independent of the doctors’ self-report (explicit biases). Doctors'implicit biases exceeded their explicit biases in all race groups studied, except for African American physicians, who did not show an implicit bias toward patients.Figure A demonstrates an AP pelvis x-ray with severe arthrosis of the right hip. The left hip demonstrates moderate disease.Incorrect Answers:

EXPLANATION: Various options exist to treat thumb CMC arthritis: trapezial resection alone, trapezial resection with ligament suspensionplasty or tendon interposition, trapezial resection with both ligament suspensionplasty and tendon interposition, CMC fusion, and CMC replacement. MCP hyperextension can develop in long-standing CMC arthritis, contributing to CMC instability as well as thumb pain and weakness. In patients with concomitant MCP hyperextension that exceeds 30°, correction of the deformity of the MCP joint must also be addressed and can be done with MCP capsulodesis, extensor pollicis brevis tendon transfer, or MCP fusion. Fusion of both the thumb CMC and MP joints is not recommended as this would result in marked stiffness and dysfunction.

DISCUSSION: Maloney and associates reported a 35% increased risk of pelvic osteolysis after total hip arthroplasty with a porous-coated acetabular component without cement. All components were stable at the time of revision. Only liners were exchanged and debridement of the granuloma with or without bone graft was performed. No defects progressed and one third of the lesions were no longer visible on radiographs, regardless of bone grafting. Unfortunately, despite the technical ease of many of these types of revisions, the dislocation rate for these cases is significant. Precautions should be taken postoperatively, and patients should be educated about this risk preoperatively.

DISCUSSION: Pagnano and associates revised 25 painful primary posterior cruciate-retaining total knee arthroplasties for flexion instability. The patients shared typical clinical presentations that included a sense of instability without frank giving way, recurrent knee joint effusion, soft-tissue tenderness involving the pes anserine tendons and the retinacular tissue, posterior instability of 2+ or 3+ with a posterior drawer or a posterior sag sign at 90° of flexion, and above-average motion of the total knee arthroplasty. Twenty-two of the knee replacements were revised to posterior stabilized implants, and three underwent tibial polyethylene liner exchange only. Nineteen of the 22 knee replacements revised to a posterior stabilized implant showed marked improvement after the revision surgery. Only one of the three knee replacements that underwent tibial polyethylene exchange was improved. Flexion instability can be a cause of persistent pain and functional impairment after posterior cruciate-retaining total knee arthroplasty. Revision surgery that focuses on balancing the flexion and extension spaces, in conjunction with a posterior stabilized knee implant, seems to be a reliable treatment for symptomatic flexion instability after posterior cruciate-retaining total knee arthroplasty. REFERENCE: Pagnano MW, Hanssen AD, Lewallen DG, Stuart MJ: Flexion instability after primary posterior cruciate-retaining total knee arthroplasty. Clin Orthop 1998;356:39-46.

DISCUSSION: The modified Hardinger approach includes a partial anterior trochanteric osteotomy creating a trochanteric wafer (as seen on the radiograph) that is displaced anterior and medial in continuity with the gluteus medius and vastus lateralis. Failure of abductor reattachment, migration of the trochanter, nonunion of the osteotomy site, and excessive splitting of the gluteus medius muscle causing injury to the inferior branch of the superior gluteal nerve can result in weakness of the abductor mechanism. Abductor strength should be evaluated with the patient lying on the opposite side and elevating the affected limb. Although slight weakness may manifest itself as a limp only after prolonged muscular activity, significant weakness results in a constant limp without associated discomfort. REFERENCES: Morrey BF (ed): Joint Replacement Arthroplasty. New York, NY, Churchill Livingstone, 1991, pp 512-526. Kasser JR (ed): Orthopedic Knowledge Update 5. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1996, pp 389-426.

THA has a higher perioperative complication rate than HA.There are a few differences between THA and HA performed in the setting of displaced FNF. THA has a higher dislocation rate, greater blood loss, requires a larger exposure than HA, and the operation is longer. HA often requires reoperation because of progressive acetabular erosion. Patient outcomes and function are greater following THA than HA.Florschultz et al. reviewed current management of FNF. They concluded that CRIF / ORIF is indicated for displaced femoral neck fractures in younger individuals, select active elderly, and medically unfit patients. HA is indicated for lower demand ambulatory older patients. THA is indicated for the active elderly and those with preexisting acetabular disease.Avery et al. reviewed 7-10 year results of an RCT comparing THA with HA. More HA patients had died during follow-up. All surviving patients had polyethylene wear (THA) and acetabular erosion (HA). They concluded that there was lower mortality and a trend towards superior function in patients with a THA in the medium term.Hedbeck et al. performed a RCT comparing HA and THA. At 4 years, there was improved function and quality of life with THA. They recommend THA in elderly, lucid patients with a displaced FNF.Incorrect Answers:

DISCUSSION: Dislocation following total hip arthroplasty is twice as common in women than in men. It is more likely to occur in older patients. There is no clear association between dislocation and the method of fixation or the type of bearing, so long as the bearing diameter is the same. REFERENCE: Berry DJ: Dislocation, in Steinberg ME (ed): Revision Total Hip Arthroplasty. Philadelphia, PA, 1999, pp 463-482.

The stiffness is most influenced by the geometry, in particular the diameter of the stem. The bending rigidity increases to the fourth power of the radius. The elastic modulus of the material increases as a direct linear relationship. The surface coating does not affect the bending rigidity greatly unless it increases the diameter significantly.

Elevated cobalt out of proportion to chromium in a patient with a metal-on-polyethylene bearing indicates mechanically assisted crevice corrosion (trunnionosis) at the modular head-neck junction. Metal-on-metal bearing wear typically produces elevated levels of both cobalt and chromium. Large diameter metal heads increase the torsional forces at the trunnion, predisposing to this complication, known as adverse local tissue reaction (ALTR) or ALVAL.

Squeaking in ceramic-on-ceramic THA is heavily associated with edge loading, which typically occurs due to component malposition (e.g., increased acetabular anteversion/inclination or loss of femoral offset). Edge loading leads to stripe wear on the ceramic head, altering fluid film lubrication and generating the audible squeak. It is generally not caused by galvanic corrosion or cement debris.