Ignore the Patella in Revision Total Knee Surgery: A Minimum 5-Year Follow-Up With Patella Component Retention.

BACKGROUND: In the setting of aseptic revision, a common question is: what should be done with the previously resurfaced patella? We report on a series of aseptic revision total knee arthroplasties (RTKA) where one or both components were revised and the patella was not. METHODS: The study group was 147 consecutive RTKA in 137 patients with a mean age of 70.1 ± 9.3 years where the patella was not revised. The average body mass index was 31.0 ± 5.4 kg/m2. Follow-up was a minimum of 5 years (range, 5 to 12 years). At final follow-up, 13 patients died and 2 patients were lost to follow-up leaving 122 patients and 130 knees available for review. Mean time from primary surgery to RTKA was 9.2 ± 5.5 years. Both components were revised in 50 knees, the femur only in 11 knees, the tibia only in 12 knees, and 57 had an isolated polyethylene revision. We found 5 patients with a mismatch between the patella and femoral components and 30 cases with patella component wear identified intraoperatively. RESULTS: At final follow-up, there were no reoperations on any patella and none were at risk of failure. There were 6 knees with a lateral patella tilt beyond 10°, but none were subluxed. Knee Society Scores averaged 85 ± 17.2 points at final follow-up. CONCLUSION: At midterm follow-up in this group of RTKA where the patella was not revised, we identified no subsequent failures of the patella. This is despite the presence of mild patella polyethylene wear and mismatched shapes in several knees. LEVEL OF EVIDENCE: III.

Gout-causing Q141K mutation in ABCG2 leads to instability of the nucleotide-binding domain and can be corrected with small molecules.

The multidrug ATP-binding cassette, subfamily G, 2 (ABCG2) transporter was recently identified as an important human urate transporter, and a common mutation, a Gln to Lys substitution at position 141 (Q141K), was shown to cause hyperuricemia and gout. The nature of the Q141K defect, however, remains undefined. Here we explore the Q141K ABCG2 mutation using a comparative approach, contrasting it with another disease-causing mutation in an ABC transporter, the deletion of Phe-508 (ΔF508) in the cystic fibrosis transmembrane conductance regulator (CFTR). We found, much like in ΔF508 CFTR, that the Q141K mutation leads to instability in the nucleotide-binding domain (NBD), a defect that translates to significantly decreased protein expression. However, unlike the CFTR mutant, the Q141K mutation does not interfere with the nucleotide-binding domain/intracellular loop interactions. This investigation has also led to the identification of critical residues involved in the protein-protein interactions necessary for the dimerization of ABCG2: Lys-473 (K473) and Phe-142 (F142). Finally, we have demonstrated the utility of using small molecules to correct the Q141K defect in expression and function as a possible therapeutic approach for hyperuricemia and gout.

Energy expenditure of femoral broaching in direct anterior total hip replacements-Comparison between manual and automated techniques.

INTRODUCTION: Little information is known regarding the energy expenditure of the surgeon during total hip arthroplasty (THA). We sought to compare the energy expenditure associated with femoral broaching using two techniques: manual and automated. METHODS: We recorded energy expenditure, minute ventilation, heart rate, and total broaching time of a single surgeon while broaching the femoral canal during direct anterior THA using two different techniques: Manual broaching (n = 26) and automated broaching (n = 20). RESULTS: Manual broaching required a longer time than automated broaching (6.1 ± 1.1 vs. 3.7 ± 0.9 min; p < 0.001) with an increase in energy expenditure (32.6 ± 7.0 vs. 16.0 ± 7.1 Calories; p < 0.001). Heart rate was higher with manual broaching (99.4 ± 9.8 vs. 90.1 ± 9.8 beats per min; p = 0.003), along with minute ventilation (36.5 ± 7.0 vs. 30.3 ± 5.8 L/min; p = 0.003). There were no intraoperative complications. CONCLUSIONS: Automated femoral broaching during THA can decrease the energy expenditure of broaching by 50% and time of broaching by 40%, when compared to manual technique. CLINICAL TRIAL REGISTRATION: This research was not a clinical trial.

Poor Patient Follow-up After Metal-on-Metal Total Hip Arthroplasty.

Routine follow-up approximately every 2 to 5 years after total hip arthroplasty (THA) is a common practice. However, although patients are informed of the importance of follow-up, our mean follow-up rate for patients after standard non-metal-on-metal (MOM) THA is only 19%. The US Food and Drug Administration has released several statements on the importance of follow-up every 2 years after MOM THA. With the potential risks of MOM THA apparently widely known, we report on our ability to obtain timely follow-up at 2 separate centers. Two separate centers performed 570 MOM THA procedures between 2002 and 2010. An attempt was made to reach every patient by either telephone or letter to obtain ion levels, radiographs, and examinations. Repeat telephone calls and/or letters to those not reached were made annually. Patients were told of the unique importance of follow-up at each contact. Of the patients, 43% had not been seen within the past 5 years, and only 26% had been seen within the past 2 years. Only 61% had their first measurement of ion levels, and only 30% of patients had a second set of measurement of ion levels. A total of 48 revisions occurred in this group, and 36 patients died. Despite the apparent widespread dissemination of information regarding the potential risks of MOM THA and concerted efforts to contact patients for follow-up, we have been able to achieve a follow-up rate of only 26%. This rate is only marginally better than the mean follow-up for non-MOM THA in our practices. The implications of this poor follow-up are unknown. [Orthopedics. 2022;45(4):e196-e200.].

Average narcotic usage in a group of TKA patients following a modern TKA protocol.

INTRODUCTION: The optimal dosing of post-operative total knee arthroplasty (TKA) narcotics is unclear. We report on the average narcotic usage in a group of patients treated with an identical multimodal pain protocol following TKA. MATERIALS AND METHODS: 49 patients undergoing TKA participated in the survey. Patients with pre-op narcotic use, recent prior total joint arthroplasty or study refusal were excluded. All patients received a spinal anesthetic. No pre-surgery narcotics were given. All received an identical local infiltrative anesthetic combination along with a multimodal pain protocol. Patients were placed into an identical rapid rehab program. Narcotic usage during hospitalization was recorded in morphine equivalent doses (MED). Patients were given a journal to record their daily narcotic utilization. RESULTS: Pre-operative pain scores of the excluded groups had slightly higher but clinically insignificant differences compared to the study group. In the hospital, POD1 study group daily MED averaged 28 (range 0-110). POD2 had an average of 33.6 and POD 3 daily usages averaged 28.6 (range 0-100). By the end of week two, the average daily use was 19.2 and 24% patients were off all narcotics. By the end of week four, the average daily usage was 7.5 and 63% of patients were off all narcotics. By 8 weeks, there were no patients still taking narcotics. KSS averaged 76.9 (range 51-97) at the 6 week visit, and 94.2 at the 3-month visit (range 72-100). SUMMARY: This study documents the average needs of an average TKA patient treated with modern pain protocols. The majority of these patients were off narcotics by week four.

Current surgical practice for septic arthritis of the knee in the United States.

For septic arthritis of the knee, we attempted to determine: the preferred surgical technique in the United-States (US), the believed "gold-standard" treatment among others. This was performed by an electronic-survey distributed to all academic orthopaedic faculty throughout the US. The preferred method was arthroscopy (69.8%). Arthroscopy is believed to be the gold-standard in 27.0%, arthrotomy in 29.4%, while 43.5% believe no gold-standard exists. In conclusion the majority of surgeons prefer arthroscopy when managing a native, septic knee in an adult patient. However, there is no national consensus on a gold-standard treatment or the role of synovectomy.

Intraoperative Tobramycin Powder Prevents Enterobacter cloacae Surgical Site Infections in a Rabbit Model of Internal Fixation.

OBJECTIVES: To evaluate the efficacy of intraoperative tobramycin powder in preventing surgical site infection (SSI) and implant colonization with Enterobacter cloacae in a rabbit fixation model. Gram-negative rods, particularly Enterobacter species, comprise an increasing percentage of SSI at our institution. METHODS: Eighteen New Zealand White rabbits underwent surgical fixation of the left tibia with implantation of a plate and screws. The surgical site and implant were inoculated with 1 × 107 CFUs E. cloacae. The selected E. cloacae isolate was resistant to tobramycin and capable of forming biofilms. Nine rabbits received 125 mg tobramycin powder directly into the surgical site, overlying the implant. The control group was untreated. Fourteen days postinfection, the tibiae and implants were explanted. Radiographs were taken with and without the implants in place. One tibia from each group was examined after hematoxylin and eosin staining. The remaining tibiae and implants were morselized or sonicated, respectively, and plated on agar to determine infection burden. Data were analyzed with Fisher exact tests and Mann-Whitney U tests. RESULTS: No bone infection or implant colonization occurred in the tobramycin-treated group. In the control group, 7 of 8 rabbits developed bone infections (P = 0.001), and 4 of 8 implants were colonized (P = 0.07). No gross disruption of the normal bone architecture was observed in either group. CONCLUSIONS: Intraoperative tobramycin powder applied at the time of contamination prevented bone infection with E. cloacae in this rabbit fixation model. The results are encouraging because the E. cloacae isolate was tobramycin-resistant, demonstrating the utility of intraoperative powdered antibiotics.

Methicillin-Resistant Staphylococcus aureus Infection Is a Risk Factor for Unplanned Return to the Operating Room in the Surgical Treatment of a Septic Knee.

Surgical irrigation and debridement is the mainstay of treatment after the diagnosis of a septic knee. Arthroscopic treatment has been validated as a treatment option, but there is limited literature comparing it to an open arthrotomy regarding risk factors for failing single-stage surgical treatment. A retrospective review of surgically treated native adult septic knees at one urban tertiary care center was conducted to evaluate rates of unplanned return to the operating room (OR) following both arthroscopic and open treatment of an adult septic knee. The primary outcome studied was unplanned return to the OR for persistent infection within 4 months of the initial surgery. Demographics, laboratory, and microbiology data were collected to identify factors associated with unplanned return visits to the OR. Fisher's exact tests and two-tailed paired Student's t-tests were used for categorical and continuous data comparisons, respectively. A multivariate analysis was performed to identify independent risk factors of initial washout failure. Thirty-three patients underwent arthroscopy and 47 had open arthrotomy. Eight failed arthroscopy and nine failed open treatment (75.8 and 80.9% success rates, p = 0.59). Unplanned repeat washouts in arthroscopically treated knees was associated with methicillin-resistant Staphylococcus aureus (MRSA) (62.5 vs. 12%, p = 0.01) and increased synovial white blood cell (WBC) count (160,000 vs. 52,000, p = 0.004). Unplanned return for repeat washout after open treatment was associated with lower American Society of Anesthesiologists scores (2.3 vs. 2.9, p = 0.019). MRSA was the only independent predictor of failure of single washout in a multivariable logistic regression analysis (p = 0.017). This study did not detect a difference in success of single washout between arthroscopic and open treatment of septic arthritis. However, MRSA was identified as a risk factor for an unplanned return to the OR after arthroscopic treatment. Consideration should be made for open surgical treatment in the setting of MRSA infections of a native knee.

Radiographic Predictors of Compartment Syndrome Occurring After Tibial Fracture.

OBJECTIVES: Compartment syndrome (CS) is a potentially devastating injury associated with tibial fractures. Few data exist regarding radiographic indicators of CS. We hypothesized that radiographic signs are associated with development of CS. DESIGN: Retrospective review. SETTING: Level I trauma center. PATIENTS: Consecutive series of adult patients with tibial fractures with (n = 56) and without (n = 922) CS. INTERVENTION: None. OUTCOMES: AO/OTA fracture classification, Schatzker type, fracture length, fibular fracture, CS diagnosis. RESULTS: The odds of CS increased by 1.67 per 10% increase in the ratio of fracture length to tibial length when considering all fractures. CS was most likely to occur with plateau fractures at 12% (shaft fractures, 3%; pilon fractures, 2%). Schatzker VI fractures were more likely to develop CS than any other Schatzker type. Fibular fracture was predictive of CS with plateau fractures only. Segmental fractures (AO/OTA type 42-C2) were not more likely to develop CS than other shaft fractures. CONCLUSIONS: Several objective and easily reproducible radiographic indicators should raise suspicion for CS. CS was more likely in plateau fractures, especially when fracture length was >20% of the tibial length, in the presence of fibular fracture, and classified as Schatzker VI. Conversely, segmental tibial shaft fractures were not more likely than other shaft fractures to develop CS. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Identification of a polycystin-1 cleavage product, P100, that regulates store operated Ca entry through interactions with STIM1.

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a genetic disorder resulting in large kidney cysts and eventual kidney failure. Mutations in either the PKD1 or PKD2/TRPP2 genes and their respective protein products, polycystin-1 (PC1) and polycystin-2 (PC2) result in ADPKD. PC2 is known to function as a non-selective cation channel, but PC1's function and the function of PC1 cleavage products are not well understood. Here we identify an endogenous PC1 cleavage product, P100, a 100 kDa fragment found in both wild type and epitope tagged PKD1 knock-in mice. Expression of full length human PC1 (FL PC1) and the resulting P100 and C-Terminal Fragment (CTF) cleavage products in both MDCK and CHO cells significantly reduces the store operated Ca(2+) entry (SOCE) resulting from thapsigargin induced store depletion. Exploration into the roles of P100 and CTF in SOCE inhibition reveal that P100, when expressed in Xenopus laevis oocytes, directly inhibits the SOCE currents but CTF does not, nor does P100 when containing the disease causing R4227X mutation. Interestingly, we also found that in PC1 expressing MDCK cells, translocation of the ER Ca(2+) sensor protein STIM1 to the cell periphery was significantly altered. In addition, P100 Co-immunoprecipitates with STIM1 but CTF does not. The expression of P100 in CHO cells recapitulates the STIM1 translocation inhibition seen with FL PC1. These data describe a novel polycystin-1 cleavage product, P100, which functions to reduce SOCE via direct inhibition of STIM1 translocation; a function with consequences for ADPKD.