Anatomy of the Lumbrical Muscles: Implications for Mechanical Advantage.

BACKGROUND: The lumbrical muscles comprise 4 intrinsic muscles of the hand and are involved in flexion of the metacarpophalangeal joint (MCPJ) and extension of the proximal interphalangeal and distal interphalangeal joints. The purpose of this study was to investigate the anatomical mechanics of the lumbrical muscles of the index, middle, ring, and small fingers. METHODS: We evaluated 25 cadaver arms and measured the distance between the MCPJ and fingertip, the distance between the MCPJ and lumbrical muscle insertion, and the distance between the MCPJ and the most proximal lumbrical muscle origin. With these measurements we calculated the needed force, insertion ratio (length of the proximal, middle, and distal phalanx divided by the MCPJ to insertion distance), and lumbrical muscle length. RESULTS: We found that the force was significantly different between all fingers, except for the comparison of the index and ring finger (P = .34). In addition, we found that muscle length was significantly different between most the fingers, except for the comparison between the index and middle fingers (P = .24), and index and ring fingers (P = .20). There was no significant difference in insertion ratio. CONCLUSIONS: Our study suggests that the anatomical mechanics for the motor function of the lumbrical muscles are similar in all fingers. This could further imply that movements are equally precise in all fingers resulting in coordination with one another and, therefore, adequate hand function. LEVEL OF EVIDENCE: IV.

Predicting Contralateral Surgery for Trapeziometacarpal Arthrosis Within 5 Years.

PURPOSE: Symptomatic trapeziometacarpal (TMC) joint arthritis is a common cause of hand pain. It is unknown how many patients ultimately elect to have bilateral surgery for TMC arthritis. In this study, we assessed the frequency and predictive factors for contralateral TMC surgery in patients who underwent prior TMC surgery. METHODS: We identified 712 patients who underwent primary surgery for TMC arthritis with a follow-up period of 5 years. We collected demographic, surgical, and follow-up data. Prediction models for contralateral surgery using a training and testing data set were created with multivariable logistic regression and random forest classifier algorithms. RESULTS: At the time of initial surgery, 230 patients had bilateral thumb pain (32%), but only 153 patients ultimately had an operation for TMC arthritis on the contralateral side within 5 years (21% of 712 total patients and 67% of 230 patients with bilateral pain). Common predictive factors between both models for contralateral surgery were younger age (odds ratio [OR] = 0.95; 95% confidence interval [CI], 0.93-0.98), bilateral thumb pain (OR = 3.76; 95% CI, 2.52-5.65), and anxiety disorders (OR = 1.84; 95% CI, 1.11-3.03). CONCLUSIONS: In our study, we found that the rate of contralateral surgery was 21% in patients who underwent prior TMC surgery. Predictive factors for future contralateral surgery included younger age, bilateral thumb pain, and anxiety disorder at the time of initial surgery. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic II.

Complications and Unplanned Reoperation After Thumb Metacarpophalangeal Arthrodesis.

PURPOSE: Arthrodesis of the metacarpophalangeal (MCP) joint of the thumb is a common procedure to treat arthritis or instability. Studies reporting hardware complications and nonunion rates after thumb MCP joint arthrodesis report on small sample sizes. We aimed to describe the hardware complication rate, the nonunion rate, and the number of thumbs that achieve union among patients undergoing thumb MCP joint arthrodesis. METHODS: A database spanning 5 urban hospitals in a single metropolitan region in the United States was searched for patients who underwent thumb MCP joint arthrodesis between January 1, 2004 and January 1, 2020. After reviewing patient records, we identified 122 thumbs that underwent MCP joint arthrodesis and had a minimum follow-up of 90 days. The primary outcome was unplanned reoperation after hardware complications and nonunion. Second, the number of thumbs that achieved radiographic union was reported for the tension band and screw fixation arthrodesis group. RESULTS: Twenty-two (18%) out of 122 thumbs had hardware complications after thumb MCP joint arthrodesis, and 11 (9%) out of 122 thumbs developed a nonunion. Patients who underwent screw fixation arthrodesis had no events of hardware complications and subsequent hardware removal. The nonunion rate was 9/65 (14%) in the tension band arthrodesis group and 2 (4%) of 45 in the screw fixation arthrodesis group. Of the thumbs that had available radiographs to assess the healing of the arthrodesis, 34 (81%) of 42 were radiographically united in the tension band arthrodesis group and 29 (91%) of 32 in the screw fixation group. CONCLUSIONS: Our data suggest that screw fixation has fewer hardware complications and a lower reoperation rate than tension band arthrodesis. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognosis IV.

From Data to Decisions: How AI Is Revolutionizing Clinical Prediction Models in Plastic Surgery.

SUMMARY: The impact of clinical prediction models within Artificial Intelligence (AI) and machine learning (ML) is significant. With its ability to analyze vast amounts of data and identify complex patterns, machine learning has the potential to improve and implement evidence-based plastic, reconstructive, and hand surgery. Among others, it is capable of predicting the diagnosis, prognosis, and outcomes of individual patients. This modeling aids daily clinical decision making, most commonly at the moment, as decision-support.Therefore, the purpose of this paper is to provide a practice guideline to plastic surgeons implementing AI in clinical decision-making or setting up AI research to develop clinical prediction models using the 7-step approach and the ABCD validation steps of Steyerberg et al. Secondly, we describe two important protocols which are in the development stage for AI research: 1) the Transparent Reporting of a multivariable prediction model for Individual Prognosis or Diagnosis (TRIPOD) checklist, and 2) The PROBAST checklist to access potential biases.

DRUJ Capsular Release for Forearm Rotational Limitation: Surgical Technique and Case Series.

BACKGROUND: Forearm stiffness can be caused by distal radioulnar joint (DRUJ) capsular contractures, which can occur after trauma such as a distal radius fracture. In this setting, a DRUJ capsular release may help improve forearm rotation, but the long-term functional outcomes remain unknown. The purpose of this case series is to investigate the short-term improvement in total pronosupination arc range of motion and long-term patient-reported outcomes (PROs) after DRUJ capsular release. METHODS: We performed a retrospective review of consecutive patients who underwent DRUJ capsular release. Range of motion prior to surgery and at final short-term follow-up was collected and analyzed with a Wilcoxon signed-rank test. Patient-reported outcomes including QuickDASH and Patient-Reported Outcomes Measurement Information System (PROMIS) Upper Extremity (UE) scores were obtained as medians with interquartile range (IQR), while patient satisfaction was measured on a 4-point Likert scale. RESULTS: Five patients met the inclusion criteria with a median short-term follow-up of 5.5 (IQR: 4.3-10.3) months. The median preoperative supination was 25° (IQR: 0°-35°), and the median postoperative supination was 50° (IQR: 40°-60°; P = .03). The median preoperative pronation was 45° (IQR: 10°-60°), and the median postoperative pronation was 70° (IQR: 60°-80°; P = .04). After the long-term median follow-up of 10.9 (IQR 9.7-11.2) years, all the patients were satisfied or very satisfied with the results of the surgery. The median QuickDASH score was 13.6 (IQR: 9.1-20.5), and the median PROMIS UE score was 46.5 (IQR: 43.8-47.7). CONCLUSIONS: Distal radioulnar joint capsular release can improve pronation and supination in patients with posttraumatic forearm stiffness and is associated with high long-term patient satisfaction.

Effect of Foliar Trimming and Fungicides on Apothecial Number of Sclerotinia sclerotiorum, Leaf Blight Severity, Yield, and Canopy Microclimate in Carrot.

Foliar trimming of the carrot canopy has potential for reducing the severity of Sclerotinia (Sclerotinia sclerotiorum) rot of carrot (Daucus carota subsp. sativus). The effect of trimming the carrot foliage once or twice, with and without fungicide application, was examined on carrot plants grown on organic soil for 3 years at the University of Guelph-Muck Crops Research Station in Ontario, Canada. The number of S. sclerotiorum apothecia, carrot leaf blight (CLB; Alternaria dauci and Cercospora carotae) severity, canopy microclimate, and total and marketable yield were assessed. The number of apothecia of S. sclerotiorum and relative humidity in the canopy were reduced by trimming done at either the first observation of apothecia or at 100 days after seeding (DAS). In both cases, the effects of trimming on canopy microclimate lasted between 2 and 4 weeks. Trimming the canopy twice during the season did not reduce the number of apothecia compared with trimming the canopy once at 100 DAS. Foliar trimming had little effect on CLB severity. This was attributed mainly to the lower requirement of the CLB pathogens for prolonged periods of high relative humidity and leaf wetness compared with S. sclerotiorum. Foliar trimming did not improve the efficacy of fungicide applications for CLB control. Trimming the canopy once or twice had no effect on total or marketable yield. Thus, trimming has potential to improve the management of Sclerotinia rot of carrot, and trimming both at first observation of apothecia and at 100 DAS could reduce apothecia production and relative humidity within the canopy.