Serum CD64 as a Marker for Chronic Periprosthetic Joint Infection.

Background: Serum cluster of differentiation 64 (CD64) has emerged as a diagnostic test for musculoskeletal infections. The purpose of this study was to evaluate the utility of serum CD64 in diagnosing periprosthetic joint infections (PJIs) compared to conventional markers like white blood count (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and interleukin-6 (IL-6). Methods: A prospective case-control study on patients undergoing revision hip or knee arthroplasty surgery >6 weeks after their index surgery was performed at a single institution. Whole blood samples were drawn within 24 hours prior to revision surgery for white blood count, ESR, CRP, IL-6, and CD64. Intraoperative cultures were obtained during the revision, and PJI was defined using the major criteria from the 2018 Musculoskeletal Infection Society criteria. Two-sample Wilcoxon rank-sum test and Fisher's exact test were used to determine if there were significant differences in serum laboratory values between patients with and without infection. The sensitivity, specificity, positive predictive value (PPV), negative predictive value, and accuracy of each test were calculated. Results: With an average age of 67 years, 39 patients with 15 revision THAs and 24 TKAs, were included. 19 patients (48.7%) were determined to have PJI. Patients with PJI had significantly higher CD64 (P = .036), CRP (P = .016), and ESR (P = .045). CD64 had the highest specificity (100%) and PPV (100%), moderate accuracy (69.2%), but low sensitivity (37.0%) and negative predictive value (62.5%). Conclusions: Given the high specificity, PPV, and accuracy, CD64 may be an excellent confirmatory test to help diagnose PJI.

Impact of Antibiotic-Impregnated Spacer Design in the Treatment of Periprosthetic Hip Infection.

Background: Although 2-stage exchange arthroplasty, consisting of temporary insertion of an antibiotic-impregnated cement spacer (AICS), is considered the standard of care for chronic periprosthetic joint infection (PJI) in total hip arthroplasty (THA), a consensus on the AICS design has not yet been established. Ceramic-on-polyethylene AICSs (Poly-AICS) are theorized to cause less pain and better function than cement-on-bone AICS (CemB-AICS) but use non-antibiotic-impregnated components that may harbor bacteria. This study evaluates the impact of spacer design on infection-free survivorship following THA reimplantation as well as pain and function during the interim AICS stage. Methods: A retrospective review was performed of all cases of THA PJI treated with either Poly-AICS or CemB-AICS at a single high-volume academic center. Data were collected until the final follow-up after THA reimplantation with an average follow-up duration of 2.6 years. The primary outcome was infection-free survivorship after the final reimplantation. Secondary outcomes included postoperative pain scores, opioid use, time to ambulation, length of stay, complications, and discharge disposition. Results: A total of 99 cases (67 CemB-AICS; 32 Poly-AICS) were included. There were no baseline differences between the 2 groups. There were no differences in infection-free survivorship after reimplantation in survivorship curve comparisons (P = .122) and no differences in postoperative inpatient pain scores, opioid use, length of stay, time to ambulation, complications, or discharge disposition during the AICS stage. Conclusions: Patients with THA PJI treated with Poly-AICS did not have worse infection-related outcomes despite the use of non-antibiotic-impregnated components but also did not appear to have less pain or improved function during the early AICS stage.

Fascia Iliaca Regional Anesthesia in Hip Fracture Patients Revisited: Which Fractures and Surgical Procedures Benefit Most?

OBJECTIVES: Perioperative fascia iliaca regional anesthesia (FIRA) decreases pain in hip fracture patients. The purpose of this study is to determine which hip fracture types and surgical procedures benefit most. DESIGN: Prospective observational study compared with a retrospective historical control. PATIENTS/PARTICIPANTS: Patients older than 60 years who received perioperative FIRA were compared with a historical cohort not receiving FIRA. SETTING: This study was conducted at a Level 1 trauma center. MAIN OUTCOME MEASUREMENTS: The primary outcome was morphine milliequivalents (MME) consumed during the index hospitalization. Fracture pattern-specific preoperative and postoperative MME consumption and surgical procedure-specific postoperative MME consumption was compared between the FIRA and non-FIRA groups. RESULTS: A total of 949 patients were included in this study, with 194 (20.4%) patients in the prospective protocol group. There were no baseline differences between cohorts. Preoperatively, only femoral neck fracture patients receiving FIRA used fewer MME (P < 0.001). Postoperatively, femoral neck fracture patients receiving FIRA used fewer MME on postoperative day (POD) 1 (P = 0.027) and intertrochanteric fracture patients used fewer MME on POD1 and POD2 (P = 0.013; P = 0.002). Cephalomedullary nail patients receiving FIRA used fewer MME on POD1 and POD2 (P = 0.004; P = 0.003). Hip arthroplasty patients receiving FIRA used fewer MME on POD1 (P = 0.037). Percutaneous pinning and sliding hip screw patients had no significant MME reduction from FIRA. CONCLUSIONS: Preoperatively, patients with femoral neck fractures benefit most from FIRA. Postoperatively, both patients with femoral neck fractures and intertrochanteric fractures benefit from FIRA. Patients undergoing cephalomedullary nail fixation or hip arthroplasty benefit most from FIRA postoperatively. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

A Comparison in Outcomes of Preoperative Single-shot versus Continuous Catheter Fascia Iliaca Regional Anesthesia in Geriatric Hip Fracture Patients.

BACKGROUND: Fascia iliaca nerve blocks relieve pain in geriatric hip fracture patients and can be administered via a single-shot or continuous catheter. We compared perioperative opioid consumption and pain scores between these two blocks. METHODS: We performed a prospective, observational cohort study, including geriatric hip fracture patients who received a preoperative block. We compared morphine milligram equivalent (MME) consumption and visual analog scale (VAS) pain scores between single-shot and continuous fascia iliaca blocks at multiple time points: preoperative and on postoperative (POD) day 0, 1, and 2. We compared the change in preoperative total and hourly opioid consumption before and after block placement within and between groups. Secondary outcomes included opioid related adverse events, length of stay, and readmission rates. RESULTS: 107 patients were analyzed, 66 received a single-shot and 41 a continuous block. No significant differences were found between both blocks at any time point for median MME consumption or pain scores. MME [IQR]: preoperative 20.5 [6.0,48.8] vs. 24.0 [8.8,48.0], p=0.95; POD0 6.0 [0.0,18.6] vs. 10.0 [0.0,14.0], p=0.52; POD1 12.0 [0.0,30.0] vs. 18.0 [5.0,24.0], p=0.69; POD2 6.0 [0.0,21.2] vs. 12.0 [0.0,24.0], p=0.54. VAS [IQR]: preoperative 4.0 [2.2,5.3] vs. 4.6 [3.2,5.3], p=0.34; POD0 1.3 [0.0,3.7] vs. 2.5 [0.0,3.6], p=0.73; POD1 2.9 [1.7,4.4] vs. 3.7 [1.5,4.7], p=0.59; POD2 2.4 [1.0,4.4] vs. 3.3 [1.9,4.2], p=0.18. Preoperative MME/hr significantly decreased after the block for both groups: 1.05 [0.0,2.2] to 0.0 [0.0,0.0], p < 0.001; 1.4 [0.6,3.1] to 0.0 [0.0,0.1], p < 0.001. The reduction in MME/hr between groups was not significantly different: 0.9 [0.0,1.9] vs. 1.4 [0.6,3.1], p = 0.067. We found no significant differences in secondary outcomes between groups. CONCLUSIONS: We report no differences in opioid use and pain scores between single-shot and continuous catheter fascia iliaca nerve blocks. Both blocks similarly reduce preoperative opioid consumption.

Time to Block: Early Regional Anesthesia Improves Pain Control in Geriatric Hip Fractures.

BACKGROUND: Fascia iliaca nerve blocks (FIBs) anesthetize the thigh and provide opioid-sparing analgesia for geriatric patients with hip fracture awaiting a surgical procedure. FIBs are recommended for preoperative pain management; yet, block administration is often delayed for hours after admission, and delays in pain management lead to worse outcomes. Our objective was to determine whether opioid consumption and pain following a hip fracture are affected by the time to block (TTB). We also examined length of stay and opioid-related adverse events. METHODS: This prospective cohort study included patients who were ≥60 years of age, presented with a hip fracture, and received a preoperative FIB from March 2017 to December 2017. Individualized care timelines, including the date and time of admission, block placement, and surgical procedure, were created to evaluate the effect that TTB and time to surgery (TTS) had on outcomes. Patterns among TTB, TTS, and morphine milligram equivalents (MME) were investigated using the Spearman rho correlation. For descriptive purposes, we divided patients into 2 groups based on the median TTB. Multivariable regression for preoperative MME and length of stay was performed to assess the effect of TTB. RESULTS: There were 107 patients, with a mean age of 83.3 years, who received a preoperative FIB. The median TTB was 8.5 hours. Seventy-two percent of preoperative MME consumption occurred before block placement (pre-block MME). A longer TTB was most strongly correlated with pre-block MME (rho = 0.54; p < 0.001), and TTS was not correlated. Patients with a faster TTB consumed fewer opioids preoperatively (12.0 compared with 33.1 MME; p = 0.015), had lower visual analog scale scores for pain on postoperative day 1 (2.8 compared with 3.5 points; p = 0.046), and were discharged earlier (4.0 compared with 5.5 days; p = 0.039). There were no differences in preoperative pain scores, postoperative opioid consumption, delirium, or opioid-related adverse events. Multivariate regression showed that every hour of delay in TTB was associated with a 2.8% increase in preoperative MME and a 1.0% increase in the length of stay. CONCLUSIONS: Faster TTB in geriatric patients with hip fracture may reduce opioid use, pain, and length of stay. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The Effect of Hamstring Tendon Autograft Harvest on the Restoration of Knee Stability in the Setting of Concurrent Anterior Cruciate Ligament and Medial Collateral Ligament Injuries.

BACKGROUND: A hamstring autograft is commonly used in anterior cruciate ligament (ACL) reconstruction (ACLR); however, there is evidence to suggest that the tendons harvested may contribute to medial knee instability. HYPOTHESIS: We tested the hypothesis that the gracilis (G) and semitendinosus (ST) tendons significantly contribute to sagittal, coronal, and/or rotational knee stability in the setting of ACLR with a concurrent partial medial collateral ligament (MCL) injury. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve human cadaveric knees were subject to static forces applied to the tibia including an anterior-directed force as well as varus, valgus, and internal and external rotation moments to quantify laxity at 0°, 30°, 60°, and 90° of flexion. The following ligament conditions were tested on each specimen: (1) ACL intact/MCL intact, (2) ACL deficient/MCL intact, (3) ACL deficient/partial MCL injury, and (4) ACLR/partial MCL injury. To quantify the effect of muscle loads, the quadriceps, semimembranosus, biceps femoris, sartorius (SR), ST, and G muscles were subjected to static loads. The loads on the G, ST, and SR could be added or removed during various test conditions. For each ligament condition, the responses to loading and unloading the G/ST and SR were determined. Three-dimensional positional data of the tibia relative to the femur were recorded to determine tibiofemoral rotations and translations. RESULTS: ACLR restored anterior stability regardless of whether static muscle loads were applied. There was no significant increase in valgus motion after ACL transection. However, when a partial MCL tear was added to the ACL injury, there was a 30% increase in valgus rotation ( P < .05). ACLR restored valgus stability toward that of the intact state when the G/ST muscles were loaded. A load on the SR muscle without a load on the G/ST muscles restored 19% of valgus rotation; however, it was still significantly less stable than the intact state. CONCLUSION: After ACLR in knees with a concurrent partial MCL injury, the absence of loading on the G/ST did not significantly alter anterior stability. Simulated G/ST harvest did lead to increased valgus motion. These results may have important clinical implications and warrant further investigation to better outline the role of the medial hamstrings, particularly among patients with a concomitant ACL and MCL injury. CLINICAL RELEVANCE: A concurrent ACL and MCL injury is a commonly encountered clinical problem. Knowledge regarding the implications of hamstring autograft harvest techniques on joint kinematics may help guide management decisions.