Influence of Bone Cement Augmentation on Complications in Cephalomedullary Nail Fixation of Geriatric Intertrochanteric Hip Fractures.

Introduction: The purpose of this study was to determine if augmentation of the helical blade with polymethylmethacrylate bone cement decreases the rates of varus cut-out and medial perforation in geriatric intertrochanteric hip fracture fixation. Methods: This was a retrospective comparative cohort study at two urban Level I trauma centers. Patients with an intertrochanteric hip fracture (classified as AO 31A1-3) who were treated with the TFN-Advanced Proximal Femoral Nailing System (TFNA) from 2018 to 2021 were eligible for the study. Medical records and post-operative radiographs were reviewed to determine procedure complications and reoperations. Results: Of the 179 patients studied, cement augmentation (CA) was used in 93 patients (52%) and no cement augmentation (NCA) was used in 86 (48%). There were no significant differences between group demographics and fracture reduction grades. Varus cut-out occurred three times in the CA group and five times in the NCA group (p = 0.48). Medial perforation occurred three times, all in the NCA group (p = 0.11). The most frequent complication was symptomatic blade lateralization from fracture collapse, with eight occurrences in the CA group compared with two in the NCA group (p = 0.10). There were 10 reoperations in the CA group and 9 in the NCA group (p = 0.99). The most common reason for reoperation was varus cut-out and the most common revision procedure was hip arthroplasty. Conclusions: Intertrochanteric hip fractures treated with the TFNA fixation system with and without cement augmentation have similar complication profiles and reoperation rates.

Association of sex and aspirin use with postoperative bleeding in patients with lower extremity long bone fractures.

Objective: The perioperative management of patients on antiplatelet drugs is a rising challenge in orthopedic trauma because antiplatelet drugs are frequently encountered and carry an increased risk of hemorrhagic consequences. The study objective was to examine the effect of aspirin on bleeding outcomes for patients with lower extremity fractures. Methods: This retrospective study included patients requiring surgical fixation of traumatic hip, femur, and tibia fractures from January 1, 2018, to March 1, 2020. Patients were excluded if they had a significant head injury, were on chronic anticoagulant therapy, or they did not receive venous thromboembolism chemoprophylaxis. Comparisons between aspirin users (patients on aspirin therapy preinjury) and non-aspirin users were examined using χ2 tests, Cochran-Mantel-Haenszel tests, and multivariate logistic regression. The primary outcome was an overt, actionable bleed (eg, blood transfusion for surgical site hemorrhage) within 24 hours postoperative. Results: There were 864 patients with lower extremity long bone fractures and 24% were aspirin users. The incidence of postoperative bleeding was 8.8% and significantly differed for patients taking aspirin versus not (13.6% vs 7.3%, p=0.01). However, biological sex at birth (M/F) was a significant effect modifier (interaction p=0.04). Among women, there were significantly more postoperative bleeds for aspirin users (17.8% aspirin vs 7.4% no aspirin, adjusted OR (AOR): 2.48 (1.28-4.81), p=0.01). Among men, there were similar postoperative bleeding events by aspirin use (5.6% aspirin vs 7.2% no aspirin, AOR: 0.50 (0.14-1.82), p=0.30). Postoperative hemoglobin values <8 g/dL were more frequent among female aspirin users (21.5% aspirin vs 12.5% no aspirin, p=0.01), but this association was not observed in men (p=0.43). Conclusion: Women taking aspirin who suffer lower extremity fractures have greater than twofold greater odds of a postoperative bleeding event. These findings suggest adequate perioperative planning to ensure blood availability, and increased awareness to monitor closely for hemorrhage in the 24-hour postoperative window for women taking aspirin preinjury. Level of evidence: IV.

The effect of restrictive fluid management on outcomes among geriatric hip fractures: a retrospective cohort study at five level I trauma centers.

Restrictive fluid management (RFM) for hemodynamically unstable trauma patients has reduced mortality rates. The objective was to determine whether RFM benefits geriatric hip fracture patients, who are usually hemodynamically stable. Design: Retrospective propensity-matched study. Setting: Five Level I trauma centers (January 1, 2018-December 12, 2018). Patients: Geriatric patients (65 years or older) with hip fractures were included in this study. Patients with multiple injuries, nonoperative management, and preoperative blood products were excluded. Intervention: Patients were grouped by fluid volume (normal saline, lactated Ringer, dextrose, electrolytes, and medications) received preoperatively or ≤24 hours of arrival; patients with standard fluid management (SFM) received ≥150 mL and RFM <150 mL of fluids. Main Outcome Measurements: The primary outcomes were length of stay (LOS), delayed ambulation (>2 days postoperatively), and mortality. Paired Student t-tests, Wilcoxon paired rank sum tests, and McNemar tests were used; an α value of < 0.05 was considered statistically significant. Results: There were 523 patients (40% RFM, 60% SFM); after matching, there were 95 patients per arm. The matched patients were well-balanced, including no difference in time from arrival to surgery. RFM and SFM patients received a median of 80 mL and 1250 mL of preoperative fluids, respectively (P < 0.001). Postoperative fluid volumes were 1550 versus 2000 mL, respectively, (P = 0.73), and LOSs were similar between the two groups (5 versus 5 days, P = 0.83). Mortality and complications, including acute kidney injuries, were similar. Delayed ambulation rates were similar overall. When stratified by preinjury ambulation status, SFM was associated with delayed ambulation for patients not walking independently before injury (P = 0.01), but RFM was not (P = 0.09). Conclusions: RFM seems to be safe in terms of laboratory results, complications, and disposition. SFM may lead to delayed ambulation for patients who are not walking independently before injury.

Coronoid Fracture Reconstruction with Ipsilateral Olecranon Osteoarticular Autograft in the Acute Setting: A Case Report.

CASE: An 18-year-old male polytrauma patient sustained a high-energy posterior fracture dislocation of his left elbow associated with a comminuted and irreparable O'Driscoll type 2 subtype 3 anteromedial facet coronoid fracture. He underwent early coronoid reconstruction using ipsilateral olecranon osteoarticular autograft with incorporation of the sublime tubercle attachment of the medial collateral ligament and repair of the lateral ulnar collateral ligament. A 3-year follow-up revealed a functional, painless, congruent, and stable elbow. CONCLUSION: Early reconstruction of a highly comminuted coronoid fracture may be a useful salvage option for the polytrauma patient, thereby avoiding complications associated with late reconstruction of posttraumatic elbow instability.

Timing of venous thromboembolism chemoprophylaxis with major surgery of lower-extremity long bone fractures.

BACKGROUND: There is debate on the need to withhold chemical venous thromboembolism (VTE) prophylaxis in patients requiring major orthopedic surgery. We hypothesized that the incidence of clinically significant hemorrhage (CSH) does not differ by the timing of prophylaxis in such patients. METHODS: This was a multicenter, retrospective cohort study conducted at five US trauma centers that included trauma patients admitted between January 1, 2018, to March 1, 2020, requiring surgical fixation of the femoral shaft, hip, or tibia and received VTE chemoprophylaxis during the hospitalization. Exclusions were major and moderate head or spinal injuries, chronic anticoagulant use, or multiple long bone surgeries. Timing of VTE chemoprophylaxis was examined as four groups: (1) initiated preoperatively without interruption for surgery; (2) initiated preoperatively but held perioperatively; (3) initiated within 12 hours postoperatively; and (4) initiated >12 hours postoperatively. The primary outcome was incidence of CSH (%), defined as overt hemorrhage within 24 hours postoperative that was actionable. Multivariate logistic regression evaluated differences in CSH based on timing of VTE chemoprophylaxis. RESULTS: There were 786 patients, and 65 (8.3%) developed a CSH within 24 hours postoperatively. Nineteen percent of patients received chemoprophylaxis preoperatively without interruption for surgery, 13% had preoperative initiation but dose(s) were held for surgery, 21% initiated within 12 hours postoperatively, and 47% initiated more than 12 hours postoperatively. The incidence and adjusted odds of CSH were similar across groups (11.3%, 9.1%, 7.1%, and 7.3% respectively; overall p = 0.60). The incidence of VTE was 0.9% and similar across groups ( p = 0.47); however, six of seven VTEs occurred when chemoprophylaxis was delayed or interrupted. CONCLUSION: This study suggests that early and uninterrupted VTE chemoprophylaxis is safe and effective in patients undergoing major orthopedic surgery for long bone fractures. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level IV.

Adherence to Antibiotic Recommendations and Infection Among Patients With Open Long-Bone Fractures: An Examination of Antibiotic Prioritization in Fracture Management.

Open fractures are at high risk of infection because of exposure of bone and tissue to the environment. Initiation of intravenous antibiotics is recommended within 1 hour of hospital arrival, although the presence of other severe injuries may lead to delays in fracture management. This retrospective study of adult patients with open long-bone fractures admitted to six level 1 trauma centers between January 1, 2018, and December 31, 2019, aimed to examine adherence to antibiotic recommendations. Associations between receiving recommendation-adherent antibiotics and patient and injury characteristics were investigated univariately and in adjusted regression analyses. The most common fracture locations among the 404 patients included were the tibia (43%) and fibula (26%). Fifty-eight percent of patients received recommendation-adherent antibiotics. After adjustment, patient demographics, comorbidities, cause of injury, and overall injury severity did not show significant associations with adherence to recommendations. Concomitant serious abdominal (adjusted odds ratio [AOR]=0.44) and spinal injuries (AOR=0.23) were associated with lower odds of receiving recommendation-adherent antibiotics. Additionally, fractures of certain locations were associated with increased odds of adherence (humerus: AOR=2.78; fibula: AOR=1.64), as were type 3 fractures (AOR=1.55). The overall infection rate was 4%, and adherence to antibiotic recommendations was not associated with infection (3% vs 5% for nonadherent, P=.34). Results suggest that although full recommendation adherence was somewhat low among this patient population, certain injury characteristics were predictive of adherence rates. Current antibiotic recommendations may benefit from consideration of how antibiotic initiation may fit into the prioritization of injury management, especially in patients with polytrauma with other severe injuries. [Orthopedics. 2023;46(1):54-58.].

Cut Cortical Screw Purchase in Diaphyseal Bone: A Biomedical Study.

Introduction: During fracture osteosynthesis, traumatologists may remove screws which are too long, cut the excess length from the screw tip, then reinsert the cut screw (CS) to minimize implant waste. The purpose of this study was to determine if this practice influences screw purchase. Methods: Using an axial-torsion load device, the maximal insertion torque (MIT) required to insert 3.5 mm stainless steel cortical screws into normal and osteoporotic bone models was measured. MIT was determined in three different test conditions: (1) long screw (LS) insertion; (2) LS insertion, removal, and insertion of a normal-length screw (NS); and, (3) LS insertion, removal, cutting excess length from the screw tip, and reinserting the CS. Results: In the normal bone model, mean (± SD) MIT of LS insertion was 546 ± 6 Newton-centimeters (N-cm) compared to 496 ± 61 N-cm for NS reinsertion and 465 ± 69 N-cm for CS reinsertion. In the osteoporotic bone model, MIT of LS insertion was 110 ± 11 N-cm, whereas the values for NS and CS reinsertions were 98 ± 9 N-cm and 101 ± 12 N-cm, respectively. There was no significant difference in MIT between CS and NS reinsertions in the osteoporotic bone analog. Conclusions: Cutting excess length from a 3.5 mm stainless steel cortical screw did not decrease its purchase regardless of bone density. During osteosynthesis, orthopaedists may remove screws which are too long, cut the screw tip, and reinsert the shortened screw as a cost-saving measure without compromising fracture fixation.

Significant variations in preoperative fluid resuscitation volumes delivered to elderly hip fracture patients at six level 1 trauma centers: an observational descriptive study.

OBJECTIVE: To describe the variations in administration of preoperative (preop) fluids and in the volumes of fluid administered among geriatric hip fracture patients requiring surgical repair. DESIGN: Observational descriptive. SETTING: Six Level 1 trauma centers. PATIENTS: A total of 595 patients aged ≥65 with ICD-10 codes indicating hip fracture and surgical repair were identified. Of these, 87.9% (n = 525) received preop fluid. The median volume of preop fluid delivered was 1500 mL (IQR: 1000-2250 mL). INTERVENTION: None. MAIN OUTCOME MEASURES: Receipt of preop fluids; median volume of fluid received. RESULTS: Receipt of preop fluid was significantly different by inter-hospital transfer, facility, BMI, hospital length of stay, and postop fluid volume. Age, sex, time to surgery, time to ambulation, and hospital disposition were not associated with preop fluid. There were significant differences in median preop fluid volumes by facility and postop fluid volume. CONCLUSION: This descriptive study of current practices among geriatric trauma patients with isolated hip fractures revealed significant differences in the use of preop fluid resuscitation and the resuscitation volumes administered. Treating facility may be the most substantial source of variation highlighting the need for a guideline on fluid resuscitation. These observed variations may be a result of patient characteristics or provider discretion and should be evaluated further.

Delayed hospital admission for traumatic hip fractures during the COVID-19 pandemic.

BACKGROUND: Concerns of contracting the highly contagious disease COVID-19 have led to a reluctance in seeking medical attention, which may contribute to delayed hospital arrival among traumatic patients. The study objective was to describe differences in time from injury to arrival for patients with traumatic hip fractures admitted during the pandemic to pre-pandemic patients. MATERIALS AND METHODS: This retrospective cohort study at six level I trauma centers included patients with traumatic hip fractures. Patients with a non-fall mechanism and those who were transferred in were excluded. Patients admitted 16 March 2019-30 June 2019 were in the "pre-pandemic" group, patients were admitted 16 March 2020-30 June 2020 were in the "pandemic" group. The primary outcome was time from injury to arrival. Secondary outcomes were time from arrival to surgical intervention, hospital length of stay (HLOS), and mortality. RESULTS: There were 703 patients, 352 (50.1%) pre-pandemic and 351 (49.9%) during the pandemic. Overall, 66.5% were female and the median age was 82 years old. Patients were similar in age, race, gender, and injury severity score. The median time from injury to hospital arrival was statistically shorter for pre-pandemic patients when compared to pandemic patients, 79.5 (56, 194.5) min vs. 91 (59, 420), p = 0.04. The time from arrival to surgical intervention (p = 0.64) was statistically similar between groups. For both groups, the median HLOS was 5 days, p = 0.45. In-hospital mortality was significantly higher during the pandemic, 1.1% vs 3.4%, p = 0.04. CONCLUSIONS: While time from injury to hospital arrival was statistically longer during the pandemic, the difference may not be clinically important. Time from arrival to surgical intervention remained similar, despite changes made to prevent COVID-19 transmission.

Clinical Outcomes of Intermediate-Length Cephalomedullary Nails for Intertrochanteric Femur Fracture Repair in Older Adults.

INTRODUCTION: Hip fracture is a major cause of morbidity and mortality in older adults. Intertrochanteric hip fractures often are treated surgically using cephalomedullary nails (CMN), in either a short or long length. Their outcomes are documented in the literature; however, outcomes of the intermediate-length CMN have not been well described. METHODS: A retrospective review was conducted of older adults with intertrochanteric hip fractures that were treated with cephalomedullary nail fixation using an intermediate-length (235 mm Synthes Trochanteric Fixation® nail or 240 mm Stryker Gamma 3®) nail. Outcome data were collected during the inpatient stay and 16 months post-operatively. RESULTS: Seventy-seven patients met inclusion criteria and were reviewed during inpatient stay; however, only 42 had documented post-operative outcomes. Of those, two patients died post-discharge and were not included in the 16-month follow-up. Comparison of results to published literature suggested that intermediate-length nails are comparable to short-length nails with regard to time in the operating room and estimated blood loss. The rate of blood transfusion was lower and length of hospital stay was shorter than in comparable studies of both short- and long-length nails. There were no post-operative peri-prosthetic fractures in the 16-month follow-up. This rate was lower than published rates for short and long nails. The hardware failure rate (3/42, 7.1%) of intermediate-length nails was higher than comparison studies of both short- and long-length nails. CONCLUSION: Patient outcomes for intermediate-length nails were similar to outcomes of shorter length nails. Utilization of the intermediate-length nail appears to be an effective treatment option for repair of intertrochanteric femur fractures. However, direct comparison is difficult since peri-prosthetic fracture rate may increase over time and nail length and hardware failure are not defined consistently in the literature. Further study is needed with a larger sample size followed over a longer period of time to confirm our findings.

Utilization of pre-hospital pelvic circumferential compression devices for pelvic fractures: survey of U.S. level I trauma centers.

INTRODUCTION: There is a lack of data on the use and effectiveness of pre-hospital pelvic circumferential compression devices (PCCD) as a temporary intervention for pelvic fracture management; they are thought to decrease pelvic volume and hemorrhage but are not without risks. The purpose of this study is to examine pre-hospital PCCD practices at US Level I trauma centers. METHODS: This was a prospective cross-sectional survey of trauma medical directors at US Level I trauma centers. The aim of this study was to describe patterns of pre-hospital PCCD utilization for pelvic fractures. Responses were compared by region, length in time the center was designated Level I, trauma patient volume, pelvic management guideline followed and blood product guidelines. Data were compared using Fisher's exact and chi-squared tests. RESULTS: Of the 158 Level I trauma centers invited, 25% responded. All Level I trauma centers use in-hospital PCCDs, whereas 71% of participant's paramedic agencies trained on pre-hospital PCCD application. Of those, 44% trained to apply pre-hospital PCCDs to all suspected pelvic fractures. A higher proportion of high-volume centers (77%) than low-volume centers (25%) trained on pre-hospital PCCD placement, p = 0.06. PCCD practices were not dependent on the trauma center's region, trauma volume, length in time as a Level I trauma center, or pelvic fracture guideline followed. CONCLUSIONS: There is widespread application of in-hospital and pre-hospital PCCD at US Level I trauma centers, however pre-hospital PCCDs are not applied to all suspected pelvic fractures. Future studies should focus on efficacy, safety, and contraindications for pre-hospital PCCDs.

A three-year retrospective multi-center study on time to surgery and mortality for isolated geriatric hip fractures.

BACKGROUND: There are multiple reports on the effect of time to surgery for geriatric hip fractures; it remains unclear if earlier intervention is associated with improved mortality, hospital length of stay (HLOS), or cost. METHODS: This was a multi-center retrospective cohort study. Patients (≥65y.) admitted (1/14-1/16) to six level 1 trauma centers for isolated hip fractures were included. Patients were dichotomized into early (≤24 h of admission) or delayed surgery (>24 h). The primary outcome was mortality using the CDC National Death Index. Secondary outcomes included HLOS, complications, and hospital cost. RESULTS: There were 1346 patients, 467 (35%) delayed and 879 (65%) early. The early group had more females (70% vs. 61%, p < 0.001) than the delayed group. The delayed group had a median of 2 comorbidities, whereas the early group had 1, p < 0.001. Mortality and complications were not significantly different between groups. After adjustment, the delayed group had no statistically significant increased risk of dying within one year, OR: 1.1 (95% CI:0.8, 1.5), compared to the early group. The average difference in HLOS was 1.1 days longer for the delayed group, when compared to the early group, p-diff<0.001, after adjustment. The average difference in cost for the delayed group was $2450 ($1550, $3400) more expensive per patient, than the early group, p < 0.001. CONCLUSIONS: The results of this study provide further evidence that surgery within 24 h of admission is not associated with lower odds of death when compared to surgery after 24 h of admission, even after adjustment. However, a significant decrease in cost and HLOS was observed for early surgery. If causally linked, our data are 95% confident that earlier treatment could have saved a maximum of $1,587,800. Early surgery should not be pursued purely for the motivation of reducing hospital costs. LEVEL OF EVIDENCE: Level III.

A descriptive survey on the use of resuscitative endovascular balloon occlusion of the aorta (REBOA) for pelvic fractures at US level I trauma centers.

BACKGROUND: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is not widely adopted for pelvic fracture management. Western Trauma Association recommends REBOA for hemodynamically unstable pelvic fractures, whereas Eastern Association for the Surgery of Trauma and Advanced Trauma Life Support do not. METHOD: Utilizing a prospective cross-sectional survey, all 158 trauma medical directors at American College of Surgeons-verified Level I trauma centers were emailed survey invitations. The study aimed to determine the rate of REBOA use, REBOA indicators, and the treatment sequence of REBOA for hemodynamically unstable pelvic fractures. RESULTS: Of those invited, 25% (40/158) participated and 90% (36/40) completed the survey. Nearly half of trauma centers [42% (15/36)] use REBOA for pelvic fracture management. All participants included hemodynamic instability as an indicator for REBOA placement in pelvic fractures. In addition to hemodynamic instability, 29% (4/14) stated REBOA is used for patients who are ineligible for angioembolization, 14% (2/14) use REBOA when interventional radiology is unavailable, 7% (1/14) use REBOA for patients with a negative FAST. Fifty percent (7/14) responded that hemodynamically unstable pelvic fractures exclusively indicates REBOA placement. Hemodynamic instability for pelvic fractures was most commonly defined as systolic blood pressure of < 90 [56% (20/36)]. At centers using REBOA, REBOA was the first line of treatment for hemodynamically unstable pelvic fractures 40% (6/15) of the time. CONCLUSIONS: There is little consensus on REBOA use for pelvic fractures at US Level I Trauma Centers, except that hemodynamically unstable pelvic fractures consistently indicated REBOA use.

Heterotopic ossification after hemiarthroplasty of the hip - A comparison of three common approaches.

OBJECTIVE: Heterotopic ossification (HO) about the hip after total hip arthroplasty and internal fixation of the hip, pelvis, and acetabulum has been linked to surgical approach. However, no study has investigated surgical approach and HO in patients undergoing hemiarthroplasty. We therefore aimed to explore the influence of operative approach in patients undergoing hemiarthroplasty. METHODS: Through a retrospective case series at an Urban level I trauma center, we found 80 patients over the age of 60 undergoing hemiarthroplasty for femoral neck fractures from 2000 to 2009. Patient charts, operative notes, and radiographs were reviewed for demographics, operative approach (anterior: A, anterior-lateral: AL, posterior: P), and any development of HO. Fisher's exact test compared rates of HO among the three approaches. Student's t-tests compared Brooker Classification levels of HO among the approaches. RESULTS: 82 hemiarthroplasties (26 A, 32 AL, 24 P) were included for analysis. 22 patients (27%) had HO. There was no significant difference in the development of HO based upon surgical approach: A: 19% (n = 5); AL: 34% (n = 11); P: 25% (n = 6). There was a significant difference in the grade of HO based on Brooker Classification (BC) with the posterior approach resulting in significantly lower grade of HO: A (BC: 2.60); AL (BC: 2.64); P (BC: 1.50) (p = 0.012). CONCLUSIONS: Our data is the first to evaluate surgical approach and HO in patients with hemiarthroplasty. Patients have a significant risk of developing higher grade HO based on surgical approach (A or AL). Orthopedists should be mindful of these risks when considering A or AL approaches.

Oocyte signals derived from polyunsaturated fatty acids control sperm recruitment in vivo.

A fundamental question in animal development is how motile cells find their correct target destinations. During mating in the nematode Caenorhabditis elegans, males inject sperm through the hermaphrodite vulva into the uterus. Amoeboid sperm crawl around fertilized eggs to the spermatheca--a convoluted tube where fertilization occurs. Here, we show that polyunsaturated fatty acids (PUFAs), the precursors of eicosanoid signalling molecules, function in oocytes to control directional sperm motility within the uterus. PUFAs are transported from the intestine, the site of fat metabolism, to the oocytes yolk, which is a lipoprotein complex. Loss of the RME-2 low-density lipoprotein (LDL) receptor, which mediates yolk endocytosis and fatty acid transport into oocytes, causes severe defects in sperm targeting. We used an RNAi screen to identify lipid regulators required for directional sperm motility. Our results support the hypothesis that PUFAs function in oocytes as precursors of signals that control sperm recruitment to the spermatheca. A common property of PUFAs in mammals and C. elegans is that these fats control local recruitment of motile cells to their target tissues.

Eph and NMDA receptors control Ca2+/calmodulin-dependent protein kinase II activation during C. elegans oocyte meiotic maturation.

Fertilization in the female reproductive tract depends on intercellular signaling mechanisms that coordinate sperm presence with oocyte meiotic progression. To achieve this coordination in Caenorhabditis elegans, sperm release an extracellular signal, the major sperm protein (MSP), to induce oocyte meiotic maturation and ovulation. MSP binds to multiple receptors, including the VAB-1 Eph receptor protein-tyrosine kinase on oocyte and ovarian sheath cell surfaces. Canonical VAB-1 ligands called ephrins negatively regulate oocyte maturation and MPK-1 mitogen-activated protein kinase (MAPK) activation. Here, we show that MSP and VAB-1 regulate the signaling properties of two Ca2+ channels that are encoded by the NMR-1 N-methyl D-aspartate type glutamate receptor subunit and ITR-1 inositol 1,4,5-triphosphate receptor. Ephrin/VAB-1 signaling acts upstream of ITR-1 to inhibit meiotic resumption, while NMR-1 prevents signaling by the UNC-43 Ca2+/calmodulin-dependent protein kinase II (CaMKII). MSP binding to VAB-1 stimulates NMR-1-dependent UNC-43 activation, and UNC-43 acts redundantly in oocytes to promote oocyte maturation and MAPK activation. Our results support a model in which VAB-1 switches from a negative regulator into a redundant positive regulator of oocyte maturation upon binding to MSP. NMR-1 mediates this switch by controlling UNC-43 CaMKII activation at the oocyte cortex.