PSAT159 Does Untreated Hypercalcemia Affect Postoperative Joint Pain Following Hip and Knee Arthroplasty for Osteoarthritis? A Retrospective Case Cohort Study

BACKGROUND/OBJECTIVE: Primary hyperparathyroidism (pHPT) is characterized by the excess secretion of parathyroid hormone (PTH), leading to hypercalcemia. pHPT is a known cause of joint pain, which is the key element in the decision regarding possible arthroplasty in patients with osteoarthritis (OA). The effect of hypercalcemia on arthroplasty outcomes has not been studied. This study investigates the association between preoperative hypercalcemia and postoperative outcomes following total knee (TKA) and total hip arthroplasty (THA). METHODS: A retrospective chart review was conducted on patients who underwent initial elective THA and/or TKA at an academic medical center between 2015-2019. Patient characteristics and outcomes were obtained. Hypercalcemia was used as a proxy for pHPT as PTH is not routinely obtained in the orthopedic setting. Patients with a preoperative serum calcium >10.2 mg/dL were matched (1: 2-1: 4) with nearest neighbor matching to patients with normal serum calcium based on age, sex, BMI, Charlson Comorbidity Index, American Society of Anesthesiologists class, type of surgery (hip or knee), and date of surgery. THA and TKA functional outcomes were measured at baseline and one-year postoperatively using patient-reported Hip Disability and Osteoarthritis Outcome Scores (HOOS JR) and Knee Injury and Osteoarthritis Outcome Scores (KOOS JR) surveys, respectively. A score of '0' represents total joint disability; '100' represents perfect joint health. Patients with incomplete HOOS JR or KOOS JR scores were excluded. Postoperative complications, readmissions, length of stay, and functional outcome scores were compared. RESULTS: Of 5215 patients identified, 269 (5%) were hypercalcemic. The final cohort included 495 patients (106 [21%] hypercalcemic cases, 389 matched controls). Of these, 223 patients underwent THA (46 [21%] cases; 177 controls) and 272 patients underwent TKA (61 [22%] cases; 211 controls). There were no differences in HOOS JR and KOOS JR scores between cases and controls at baseline (HOOS JR: 49.6±12.9 vs 52.8±13.3; KOOS JR: 52.5±12.1 vs 53.5±11.4) or at one-year postoperatively (HOOS JR: 83.6±16.2 vs 84.7±15.5; KOOS JR: 78.0±13.1 vs 75.5±15.3). There also were no differences in rates of postoperative complications, readmissions, or length of stay. Only 19/106 (18%) hypercalcemic patients had a PTH drawn, and of these, 9 (47%) had possible pHPT (PTH>40). Sub-analysis of these 9 patients demonstrated similar HOOS JR and KOOS JR scores to controls at both timepoints. CONCLUSION: Patients with hypercalcemia undergoing arthroplasty have similar functional and postoperative outcomes as normocalcemic patients. Analysis of patients with possible pHPT was limited, as a PTH was obtained in <20% of patients with hypercalcemia. However, nearly 50% of these patients had possible pHPT. Therefore, we recommend that all patients being evaluated for arthroplasty have a calcium level checked, and if high, be evaluated for possible pHPT. Additional investigation is needed to determine the effect of pHPT on arthroplasty outcomes. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.