Tobacco Use Is Associated with More Severe Adverse Outcomes Than Morbid Obesity after Aseptic Revision TKA.

The association of morbid obesity with increased revision total knee arthroplasty (rTKA) complications is potentially confounded by concurrent risk factors. This study was performed to evaluate whether morbid obesity was more strongly associated with adverse aseptic rTKA outcomes than diabetes or tobacco use history-when present as a solitary major risk factor. Demographic characteristics, surgical indications, and adverse outcomes (reoperation, revision, infection, and amputation) were compared between 270 index aseptic rTKA performed for patients with morbid obesity (n = 73), diabetes (n = 72), or tobacco use (n = 125) and 239 "healthy" controls without these risk factors at a mean 75.7 (range: 24-111) months. There was no difference in 2-year reoperation rate (17.8 vs. 17.6%, p = 1.0) or component revision rate (8.2 vs. 8.4%) between morbidly obese and healthy patients. However, higher reoperation rates were noted in patients with diabetes (p = 0.02) and tobacco use history (p < 0.01), including higher infection (p < 0.05) and above knee amputation (p < 0.01) rates in patients with tobacco use history. Multivariate analysis retained an independent association between smoking history and amputation risk (odds ratio: 7.4, 95% confidence interval: 1.7-55.2, p < 0.01). Morbid obesity was not associated with an increased risk of reoperation or component revision compared with healthy patients undergoing aseptic revision. Tobacco use was associated with increased reoperation and above knee amputation. Additional study will be beneficial to determine whether risk reduction efforts are effective in mitigating postoperative complication risks.

Isolated Liner Revision for Total Knee Arthroplasty Instability: A Road That Should Remain Less Taken.

Isolated polyethylene liner exchange (IPLE) is infrequently selected as a treatment approach for patients with primary total knee arthroplasty (TKA) prosthetic joint instability. Potential advantages of less immediate surgical morbidity, faster recovery, and lower procedural cost need to be measured against reoperation and re-revision risk. Few published studies have directly compared IPLE with combined tibial and femoral component revision to treat patients with primary TKA instability. After obtaining institutional review board (IRB) approval, we performed a retrospective comparison of 20 patients treated with IPLE and 126 patients treated with tibial and femoral component revisions at a single institution between 2011 and 2018. Patient demographic characteristics, medical comorbidities, time to initial revision TKA, and reoperation (90 days, <2 years, and >2 years) were assessed using paired Student's t-test or Fisher's exact test with a p-value <0.01 used to determine significance. Patients undergoing IPLE were more likely to undergo reoperation (60.0 vs. 17.5%, p = 0.001), component revision surgery (45.0 vs. 8.7%, p = 0.002), and component revision within 2 years (30.0 vs. 1.6%, p < 0.0001). Differences in 90-day reoperation (p = 0.14) and revision >2 years (p = 0.19) were not significant. Reoperation for instability (30.0 vs. 4.0%, p < 0.001) and infection (20.0 vs. 1.6%, p < 0.01) were both higher in the IPLE group. IPLE does not provide consistent benefits for patients undergoing TKA revision for instability. Considerations for lower immediate postoperative morbidity and cost need to be carefully measured against long-term consequences of reoperation, delayed component revision, and increased long-term costs of multiple surgical procedures. This is a level III, case-control study.

Revision TKA for Instability: Poorer Outcomes after a Previous Aseptic Revision.

Instability is a common indication for early revision total knee arthroplasty (rTKA). The comparative performance of instability rTKA performed after primary TKA and instability rerevision TKA (rrTKA) performed after a previous rTKA performed for any aseptic indication have not been defined. This study was performed to determine the rate of adverse outcomes for patients undergoing aseptic instability TKA revision following a primary TKA or a previous aseptic any-cause rTKA. After obtaining Institutional Review Board approval, we retrospectively identified 126 rTKA and 28 rrTKA component revision procedures performed for an exclusive instability diagnosis between January 1, 2011 and April 30, 2018. We excluded patients undergoing isolated liner exchange, single component revision for mid-flexion instability, and patients treated with a constrained hinge. Patient demographic characteristics, medical comorbidities, time to initial revision TKA, and adverse postrevision outcomes (reoperation, component revision, infection, amputation) were assessed using paired Student's t-test or Fisher's exact test with a p-value < 0.05 used to determine significance. Patients in the rrTKA cohort were more commonly female (57.1 vs. 27.8%, p < 0.01), with no other demographic differences. The rrTKA cohort had higher reoperation (39.3 vs. 18.4%, p = 0.02) and component revision rates (25.0 vs. 8.7%, p = 0.03), with a trend towards early reoperation < 2 years after surgery (25.0 vs. 11.1%, p = 0.07). The rrTKA cohort also had higher adverse outcomes related to infection (14.3 vs. 1.6%, p = 0.01), extensor mechanism failure (14.3 vs. 3.2%, p = 0.04) and above-knee amputation (14.3 vs. 2.4%, p = 0.02). Component revision is beneficial for patients with TKA instability; however, higher adverse outcome rates occur after instability rrTKA performed after a previous aseptic any-cause rTKA. Infection prevention and extensor mechanism protection are important to minimize the most common adverse outcomes identified among patients undergoing aseptic rrTKA for instability.

Does Irrigating While Drilling Decrease Bone Damage?

Background: Heat generated during bone drilling may be associated with thermal necrosis and direct damage, leading to complications after surgery. This preclinical study evaluates the in vivo effects of saline irrigation, drilling device type, and device sharpness on heat generation and bone damage in viable cortical bone. Methods: Bicortical drilling of each tibial diaphysis from anesthetized research dogs was performed to evaluate temperature and bone damage using five different devices with or without saline irrigation. Results: Saline irrigation and sharp drill bits were associated with smaller temperature increases and less acute osteonecrosis. Conventional trocar tip Kirschner wires were associated with the largest temperature increase and the most acute osteonecrosis changes. Conclusion: The use of saline irrigation during bone drilling reduces temperature change and osteonecrosis. Furthermore, we recommend that the use of dull drill bits or standard tip Kirschner wires be avoided. Lastly, drill bit design can directly contribute to bone damage during drilling. Clinical Relevance: This study provides in vivo data from a preclinical model to validate the benefits of saline irrigation and sharp drill bits during bone drilling to regulate increases in temperature and decrease associated osteonecrosis. Risk for early implant loosening and poor surgical outcome is influenced by thermal osteonecrosis of bone such that consistent use of saline irrigation, sharp drill bits, and optimized designs may have important clinical advantages. Level of Evidence: II.

Revision Total Knee Arthroplasty in Young Patients: Higher Early Reoperation and Rerevision.

BACKGROUND: Revision total knee arthroplasty (rTKA) rates are increasing in younger patients. Few studies have assessed outcomes of initial aseptic rTKA performed for younger patients compared with traditional-aged patients. METHODS: A detailed medical record review was performed to identify patient demographics, medical comorbidities, surgical rTKA indications, timing from index TKA to rTKA, subsequent reoperation rates, component rerevision rates, and salvage procedures for 147 young patients (158 knees) aged 55 years and younger and for a traditional older cohort of 276 patients (300 knees) between 60 and 75 years. Univariate analysis was performed to assess differences in these primary variables, and a log-rank test was used to estimate 5-year implant survival based on either reoperation or component revision and salvage procedures. RESULTS: Younger TKA patients were more likely to undergo initial aseptic rTKA within 2 years of their primary TKA (52.5% vs 29.0%, P < .001) and were more likely to undergo early reoperation (17.7% vs 9.7%, P = .02) or component rerevision (11.4% vs 6.0%, P < .05) after rTKA. Infection and extensor mechanism complications were more commonly noted in younger patients. Estimated 5-year survival was also lower for both reoperation (59.4% vs 65.7%, P = .02) and component rerevision or salvage (65.8% vs 80.1%, P = .02). CONCLUSION: Early reoperation and component re-rTKA were performed nearly twice as often in younger rTKA than traditional-aged TKA patients. Care should be given to reduce perioperative infection and extensor mechanism failures after rTKA in younger patients.