Scoping review of the palmaris profundus muscle: anatomy of a rare variant and its role in carpal tunnel syndrome.

The palmaris profundus muscle is a rare anatomical variation of the forearm muscles. It has been described in both cadaveric and clinical studies as a possible cause of carpal tunnel syndrome. We observed three cases of this variant in recent years and decided to perform a scoping review of this uncommon anatomical entity. Major databases were searched to identify all relevant clinical and anatomical studies containing anatomical descriptions of the muscle, including its origin, insertion, and concomitant presence of the proper palmaris longus muscle or the bifid median nerve. In clinical cases, we studied the surgical approach. Sixty-four articles met our inclusion criteria and contained 88 cases of palmaris profundus muscle. The most common origin was the ventral aspect of the radius in the area of insertion of the pronator teres muscle observed in 11 cases (12.5 %). We found 65 cases (73.3%) in which the tendon was inserted into the palmar aponeurosis or palmar fascia after entering the carpal canal. The concomitant presence of the proper palmaris longus muscle was described in 47 cases (53.4%). We identified 10 cases (10.8%) of the bifid median nerve. In 49 of 69 clinical cases (71%), the surgical approach was to resect the variant muscle. The importance of this variant should not be underestimated due to its potential to compress the median nerve. We found a significant disparity in the muscle origin sites, but uniformity of muscle insertion. In cases where the muscle is found during carpal canal surgery, it should be partially resected to ensure complete nerve decompression.

Prevalence of the anterosuperior capsulolabral anatomical variations and their association with pathologies of the glenoid labrum: a systematic review and meta-analysis.

PURPOSE: Differentiating the anatomical variations of the anterosuperior portion of the glenoid labrum from pathologies is important to avoid unnecessary iatrogenic complications resulting from inaccurate diagnosis. Additionally, the presence of several variations was reported to be conductive to lesions involving the glenoid labrum. Thus, the aim of this study was to state the prevalence rates of the sublabral recess, sublabral foramen, and the Buford complex, and to verify their association with labral lesions. METHODS: Systematic search of electronic databases was conducted to gain potentially eligible literature. Suitable studies were selected in a two-round screening, and relevant data were subsequently extracted. Calculation of the pooled prevalence estimates, including sub-analyses on cohort size, study type, and geographical variance, was conducted. Pooled analysis of risk ratios (RR) was used to assess the conductive nature of the discussed variants to superior labrum anterior to posterior (SLAP) lesions. RESULTS: The screening resulted in selection of 20 studies investigating the morphological features of the glenoid labrum, consisting of 7601 upper limbs. On the bases of random-effects meta-analysis the sublabral recess, sublabral foramen and Buford complex occur with a pooled prevalence of 57.2% (95% CI 30.0-84.4%), 13.5% (95% CI 8.2-18.9%), and 3.0% (95% CI 1.5-4.5), respectively. Moreover, individuals with Buford complex have RR 2.4 (95% CI 1.3-4.7) of developing SLAP lesions, especially type II (95.5%; 95% CI 86.1-100%), whereas such risk for sublabral recess and sublabral foramen was not statistically significant. CONCLUSION: Morphological variants of the glenoid labrum posing diagnostic confusion are frequently observed. Gradually, the Buford complex may be a predisposing factor for sustaining a SLAP lesion.

Anatomical variants complicating the posterior approaches towards the elbow joint.

INTRODUCTION: Anatomical variants observed during the posterior approach to the elbow joint require special attention due to their clinical relevance. We aim to present a compendious review of described variants potentially encountered during the posterior approach towards the elbow joint to the experts in the elbow surgery. METHODS: A narrative review of surgical and anatomical textbooks, as well as search of scientific databases was carried out. RESULTS: Variability of the subcutaneous nerves is important during incision planning. Accessory muscles such as dorsoepitrochlearis, chondroepitrochlearis, epitrochleoanconeus, subanconeus or supernumerary flexor carpi ulnaris may confuse even the senior surgeon during the dissection and possibly complicate the fracture reduction. Some bony variants such as supratrochlear foramen may lead to fracture or possibly interfere with the osteosynthesis placement. Accessory bones are also present in the region of the elbow joint. Those situated intra-articular may present with symptoms. CONCLUSION: Many variants can be encountered in the area of the elbow joint and their knowledge is essential to truly understand its anatomy. The presented review enables easier orientation in the current literature with the aim on the posterior approach towards the elbow joint.

Variations of the lumbrical muscles of the hand: Systematic review and meta-analysis.

PURPOSE: Lumbrical muscles of the upper limb belong to the middle group of intrinsic hand muscles. Their anatomical variability has been extensively studied with heterogeneous findings. Therefore, the aim of this study is to provide a systematic review and a meta-analysis of the lumbrical muscles variations in the human hand. METHODS: For this purpose, four major electronic databases were searched to identify eligible studies. Then, all relevant data were extracted, and statistical analysis performed. A new classification of lumbrical muscles variations is proposed to summarize and clearly define all described findings. We included 26 studies, making a total sample of 1340 dissected hands. FINDINGS: The most common variations for each muscle were an accessory belly for the first lumbrical muscle, a variable origin for the second lumbrical muscle, a variable innervation for the third lumbrical muscle and a variable insertion for the fourth lumbrical muscle with the prevalence 3.8%; 7.7%; 12% and 5.8%, respectively. CONCLUSIONS: We believe that results of our statistical analysis are suitable for both hand surgeons and other medical professionals dealing with hand injuries or functional problems in their daily routine.

The arcade of Frohse: a systematic review and meta-analysis.

PURPOSE: The structure of the proximal margin of the superficial layer of the supinator muscle is of high interest to many researches. Its tendinous appearance, called the arcade of Frohse, may be clinically important because of its close relationship to the deep branch of the radial nerve passing beneath it and is considered to be the cause of several syndromes. Given the importance of this structure, we aimed to provide a comprehensive and evidence-based review with meta-analytic techniques. MATERIALS AND METHODS: The meta-analysis was performed in adherence to the PRISMA guidelines. Three medical databases were searched in order to identify all potentially eligible articles. Included studies were assessed for quality and the extracted morphological and morphometric data from the relevant articles was analyzed with the use of random effects meta-analysis. RESULTS: A total of 20 studies were included into this meta-analysis. The pooled prevalence of the arcade of Frohse was calculated to be 66% within the adult population and 0% in the fetuses. Other variations regarding the arcade of Frohse were identified as very rare. Analysis of the morphometric parameters revealed the average proportions to be 23.22 mm for the length, 11.05 mm for the width and the mean thickness is 0.67 mm. CONCLUSIONS: The arcade of Frohse is a commonly found structure in adults and thoughtful knowledge of its texture and morphology is especially useful in neurology, neurosurgery, orthopedics, trauma surgery and hand surgery, because it is considered to be the most common source of compression for the deep branch of the radial nerve.

The superficial anatomical landmarks are not reliable for predicting the recurrent branch of the median nerve.

PURPOSE: The variability of the recurrent branch (RB) of the median nerve lends itself to an increased risk of injury when performing the minimally invasive approach for carpal tunnel release without its direct visualization. This risk is less so when it is released via the more invasive open approach as the RB can be easily identified, but the drawback is that of longer postoperative patient recovery time. Therefore, performing these releases via the less invasive approach should be more favorable for patients providing it could be done safely. Hence with there being a positive link between the hypertrophy of the thenar musculature and the course of RB according to previous studies. METHODS: We dissected 28 hands of 14 donated bodies fixed using Thiel's method to try to demonstrate these findings of the associations among the RB, palmar creases and other superficial anatomical landmarks. Fisher's exact test was conducted to verify the relationship between those structures statistically. RESULTS: Statistically significant links were found between the type of the RB and the type of the palmar creases (p value = 0.0094) and between the RB type and the palmaris longus muscle presence (p value = 0.028). CONCLUSION: It was inferred that palmar creases and other superficial anatomical landmarks listed in the text could not be used to predict the variability of the RB and the choice of mini-invasive approach should not be based on their course.

Absence of flexor digitorum profundus muscle and variation of flexor digitorum superficialis muscle in a little finger: two case reports.

PURPOSE: Knowledge of rare variants of the FDP is of high clinical importance for physicians examining patients for tendon lacerations and especially for hand surgeons operating tendon injuries. METHODS: During routine dissection at our Department of Anatomy both cases were observed. RESULTS: Variations of flexor digitorum superficialis and flexor digitorum profundus muscles of the little finger were observed in two cadavers. In both cases, the flexor digitorum profundus muscle for the little finger was absent. Moreover, in the first case, the flexor digitorum superficialis muscle for the little finger was hypoplastic and in the second case it featured variable insertion. CONCLUSION: There were found only four cases in previous literature describing absent flexor digitorum profundus tendon without any muscle attachment to the base of the distal phalanx. Furthermore, all previously described cases were observed in living patients. To our best knowledge, a case report in cadaver has yet not been reported and is of high importance for hand surgeons examining the hand for tendon injuries.

Accessory flexor carpi ulnaris muscle with associated anterior interosseous artery variation: case report with the definition of a new type and review of concomitant variants.

PURPOSE: Knowledge of accessory flexor carpi ulnaris (AFCU) is not only important for proper orientation in the surgical field but it can be used for tendon transfer as well. AFCU commonly occurs with concomitant variants, and its presence should rise caution in order to prevent iatrogenic injury. METHODS: During a routine dissection for research data collection at the Institute of Anatomy, a AFCU with concomitant variants was observed in a European cadaver fixed with Thiel's method. A thorough review of the literature concerning all the encountered variants was performed. RESULTS: AFCU was found in the right upper limb with its insertion on the flexor retinaculum. Palmaris longus muscle was absent in this limb, and an accessory branch of the anterior interosseous artery coursed over the pronator quadratus muscle to anastomose with the ulnar artery 5 cm proximally to the pisiform. On the left hand, a variable lumbrical of the second finger originating from the flexor retinaculum was found, which was not described in the literature before. CONCLUSIONS: AFCU commonly occurs together with concomitant variants, and special attention is needed when performing surgery on such forearm.