Effects of Leg Length, Sex, Laterality, and the Intermediate Femoral Cutaneous Nerve on Infrapatellar Innervation.

Background: An iatrogenic injury to the infrapatellar branch of the saphenous nerve (IPBSN) is a common precipitant of postoperative knee pain and hypoesthesia. Purpose: To locate potential safe zones for incision by observing the patterns and pathway of the IPBSN while examining the relationship of its location to sex, laterality, and leg length. Study Design: Descriptive laboratory study. Methods: A total of 107 extended knees from 55 formalin-embalmed cadaveric specimens were dissected. The nerve was measured from palpable landmarks: the patella at the medial (point A) and lateral (point B) borders of the patellar ligament, the medial border of the patellar ligament at the patellar apex (point C) and tibial plateau (point D), the medial epicondyle (point E), and the anterior border of the medial collateral ligament at the tibial plateau (point F). The safe zone was defined as 2 SDs from the mean. Results: Findings indicated significant correlations between leg length and height (r P = 0.832; P < .001) as well as between leg length and vertical measurements (≥45°) from points A and B to the IPBSN (r P range, 0.193-0.285; P range, .004-.049). Male specimens had a more inferior maximum distance from point A to the intersection of the IPBSN and the medial border of the patellar ligament compared with female specimens (6.17 vs 5.28 cm, respectively; P = .049). Right knees had a more posterior IPBSN from point F compared with left knees (-0.98 vs-0.02 cm, respectively; P = .048). The majority of knees (62.6%; n = 67) had a nerve emerging that penetrated the sartorius muscle. Additionally, 32.7% (n = 35) had redundant innervation, and 25.2% (n = 27) had contribution from the intermediate femoral cutaneous nerve (IFCN). Conclusion: We identified no safe zone. Significant innervation redundancy with a substantial contribution to the infrapatellar area from the IFCN was noted and contributed to the expansion of the danger zone. Clinical Relevance: The location of incision and placement of arthroscopic ports might not be as crucial in postoperative pain management as an appreciation of the variance in infrapatellar innervation. The IFCN is a common contributor. Its damage could explain pain refractory to SN blocks and therefore influence anesthetic and analgesic decisions.

Comorbid Patterns in the Homeless Population: A Theoretical Model to Enhance Patient Care.

INTRODUCTION: From the perspective of social determinants, homelessness perpetuates poor health and creates barriers to effective chronic disease management, necessitating frequent use of emergency department (ED) services. In this study we developed a screening algorithm (checklist) from common comorbidities observed in the homeless population in the United States. The result was a theoretical screening tool (checklist) to aid healthcare workers in the ED, including residents, medical students, and other trainees, to provide more efficacious treatment and referrals for discharge. METHODS: In this retrospective cohort study we used the Nationwide Emergency Department Sample (NEDS) to investigate comorbidities and ED utilization patterns relating to 23 injury-related, psychiatric, and frequent chronic medical conditions in the US adult (≥18 years of age) homeless population. Cases were identified from the NEDS database for 2014-2017 using International Classification of Diseases, 9th and 10 revisions, and Clinical Classification Software diagnosis codes. We performed a two-step cluster analysis including pathologies with ≥10% prevalence in the sample to identify shared comorbidities. We then compared the clusters by sociodemographic and ED-related characteristics, including age, gender, primary payer, and patient disposition from the ED. Chi-square analysis was used to evaluate categorical variables (ie, gender, primary payer, patient disposition from the ED), and analysis of variance for continuous variables (age). RESULTS: The study included 1,715,777 weighted cases. The two-step cluster analysis identified nine groups denominated by most prevalent disease: 1) healthy; 2) mixed psychiatric; 3) major depressive disorder (MDD); 4) psychosis; 5) addiction; 6) essential hypertension; 7) chronic obstructive pulmonary disease (COPD); 8) infectious disease; and (9) injury. The MDD, COPD, infectious disease, and Injury clusters demonstrated the highest prevalence of co-occurring disease, with the MDD cluster displaying the highest proportion of comorbidities. Although the addiction cluster existed independently, substance use was pervasive in all except the healthy cluster (prevalence 36-100%). We used the extracted screening algorithm to establish a screening tool (checklist) for ED healthcare workers, with physicians as the first point of contact for the initial use of the screening tool. CONCLUSION: Healthcare workers in the ED, including residents, medical students, and other trainees, provide services for homeless ED users. Screening tools (checklists) can help coordinate care to improve treatment, referrals, and follow-up care to reduce hospital readmissions. The screening tool may expedite targeted interventions for homeless patients with commonly occurring patterns of disease.