Kaissar Yammine

Evidence-Based Anatomy

Anatomy is a descriptive basic medical science that is no longer considered a research‐led discipline. Many publications in clinical anatomy are prevalence studies treating clinically relevant anatomical variations and reporting their frequencies and/or associations with variables such as age, sex, side, laterality, and ancestry. This article discusses the need to make sense of the available literature. A new concept, evidence‐based anatomy (EBA), is proposed to find, appraise, and synthetize the results reported in such publications. It consists in applying evidence‐based principles to the field of epidemiological anatomy research through evidence synthesis using systematic reviews and meta‐analyses to generate weighted pooled results. Pooled frequencies and associations based on large pooled sample size are likely to be more accurate and to reflect true population statistics and associations more closely. A checklist of a typical systematic review in anatomy is suggested and the implications of EBA for practice and future research, along with its scope, are discussed. The EBA approach would have positive implications for the future preservation of anatomy as a keystone basic science, for sound knowledge of anatomical variants, and for the safety of medical practice. Clin. Anat. 27:847–852, 2014.

Clinical prevalence of palmaris longus agenesis: A systematic review and meta-analysis

We report a systematic review and a proportion meta‐analysis of prevalence studies evaluating the prevalence of palmaris longus agenesis (PLA) in the literature. The overall PLA rate was defined to be the primary outcome. Secondary outcomes were rates of PLA in relation to ethnicity, laterality, side, gender, age, and hand dominance. We identified 26 articles which met the inclusion criteria. Meta‐analyses showed an overall PLA pooled rate of 20.25%, higher than the commonly reported overall rate of 15%. Our results also showed significantly lower pooled rates in Africans (11.3%) and East Asians (4.5%) when compared to Arab Middle Eastern population (41.7%). A subgroup analysis of the African group showed a pooled rate of 2.71%, the lowest, in the East and South East African population. The pooled rate was 26.3% among Caucasians, 26.16% among South and Southeast Asians and 34.13% among Turkish. In discordance with the literature, PLA was statistically more predominant on the right side. No significant differences in PLA rates were found for laterality, gender, the combination of gender and side or the combination of gender and laterality. The lowest rate of PLA found in East and South East African populations might be indicative of the subsequent phylogenetic degeneration of the palmaris longus muscle in modern humans after the “Out of Africa” migration. Clin. Anat. 26:709–718, 2013.

The prevalence of os acromiale: A systematic review and meta‐analysis

Os acromiale (OA) results from a failure of consolidation between the ossification centers of the acromial epiphysis. Its prevalence and its interactions with ancestry, gender, laterality, and side have been variously reported in the literature. The aims of this review are to provide an accurate estimate of OA prevalence and to investigate its association with other variables in an attempt to comprehend its etiology. Twenty‐three studies met the inclusion criteria. The results of meta‐analyses of large‐sample studies revealed: (a) a crude overall prevalence of 7.0%, (b) a crude cadaveric prevalence of 7.6%, (c) a crude archeological (skeletal) prevalence of 5.6%, (d) a crude radiological prevalence of 4.2%, (e) a true anatomical prevalence of 9.6%, (f) a significantly higher frequency in persons of black ancestry than in persons of white, Native American and Middle Eastern ancestries (OR ≈ 3), (g) significantly higher unilateral and bilateral frequencies in black ancestry (OR of 2 and 4, respectively), (h) nonsignificant interactions of OA frequency with gender and side. The commonest type of OA was the meso‐acromion type (76.6%). Degenerative changes were present in 66.6% of OAs. The results of this evidence‐based anatomical review support a genetic basis for OA rather than the mechanical trauma‐induction hypothesis. Clin. Anat. 610–621, 2014.

The prevalence of the sesamoid bones of the hand: A systematic review and meta-analysis

The literature contains various estimates of the prevalence and distribution of the sesamoid bones in the hands. The aims of this systematic review are to provide a better estimate of the frequency of hand sesamoids and its association with variables such as ancestry, gender, and side. Nineteen studies met the inclusion criteria. The pooled rates of the sensitive meta‐analyses from large‐sample studies in adults showed: (a) true overall rates of 99.9% for the metacarpophalangeal (MCP) joint of the thumb (MCP‐I), 53% for the interphalangeal joint (IP‐I), 43.4% for the MCP of the index (MCP‐II), 1.47% for the MCP of the medius finger (MCP‐III), 0.6% for the MCP of the ring finger (MCP‐IV), and 67.7% for the MCP of the auricular finger (MCP‐V); (b) true radiological rates of 99.9% for the radial thumb sesamoid, 99.6% for the ulnar thumb sesamoid, 47.8% for IP‐I, 40% for MCP‐II, 1.3% for MCP‐III, 0.8% for MCP‐VI, and 62.8% for MCP‐V. Black, Middle Eastern, and European ancestries conferred significantly higher sesamoid frequencies at IP‐I, MCP‐II, and MCP‐V, respectively. There was a significant association with female gender at MCP‐II, MCP‐IV, and MCP‐V, with ORs of 1.53, 4, and 1.3, respectively, and a nonsignificant “female” trend for the other locations. There was no significant association with hand side. The pooled rates of hand sesamoids in children aged 10–17 years were 92.7, 42.2, 33.8, 0.5, 0.3, and 36.5% for MCP‐I, IP‐I, MCP‐II, MCP‐III, MCP‐IV, and MCP‐V, respectively. The findings of this evidence‐based anatomical review provide quantitative evidence that the incidence of sesamoid bones in human hands depends on genetic rather than functional factors. Clin. Anat. 27:1291–1303, 2014.

Formaldehyde exposure and its effects during pregnancy: Recommendations for laboratory attendance based on available data.

Formalin is commonly used in fixation of cadaveric specimens. Exposure to formaldehyde, a component of formalin and a known carcinogen, during gross anatomy laboratory dissection is a continuing concern for pregnant students and instructors. Since there is little literature on this specific topic, the current review was compiled in the hope of offering recommendations to pregnant students and instructors who are engaged in human anatomical dissection where formalin is used. Relevant articles were obtained through searches of PubMed and Google Scholar for the terms “formaldehyde,” “pregnant,” “formalin,” and “exposure.” A literature search was conducted for chemical information and articles about exposure as issued by government regulatory agencies and chemical companies that produce formaldehyde. This led to the compilation of 29 articles each of which included references to previous, relevant, human research. The reviewed literature contains data strongly suggesting that pregnancy can be affected by formaldehyde exposure. Therefore, on the basis our analysis, female students who might be pregnant should avoid formaldehyde exposure, including that in a gross anatomy laboratory. Instructors should find other means of ensuring anatomical competence for these students. Clin. Anat. 28:972–979, 2015.

Efficacy of repair techniques of the Achilles tendon: A meta-analysis of human cadaveric biomechanical studies

PURPOSE Achilles injuries are very common, mainly among young athletes. When indicated, the surgical treatment aims for strong repairs that can resist distraction and consequently ruptures. The majority of the published clinical meta-analyses reported comparisons between broad treatment modalities such as conservative treatment, open, and minimally invasive surgery. METHODS A meta-analysis has been conducted to assess further clinical and biomechanical variables on human cadavers related to the efficacy of Achilles repair. A total of 26 studies with 596 legs met the inclusion criteria. The maximal load to failure was set as the primary outcome. Eleven studies were amenable to meta-analysis. RESULTS In the reinsertion group, the analysis of the single row vs. double row subgroup showed a significantly higher strength for the latter (1.27, 95% CI=0.748-1.806, I2=81%, P<0.0001). In the mid-tendon repair group, the Achillon vs. Krackow sutures and the Bunnell vs. Krackow sutures subgroups showed no difference while the Bunnell and Krakow sutures were significantly stronger than the Kessler sutures (0.96, 95% CI=0.510-1.405, I2=63.3%, P<0.0001 and 1.37, 95% CI=2.286-0.468, I2=83.4%, P=0.003; respectively). CONCLUSIONS The assessment of heterogeneity located variables such as age, suture/material type, number of strands, type of testing machine and software, preloading, ankle position and loading type as potential confounders. The results of this meta-analysis are likely to have a significant impact in clinical practice.

Patterns of the superficial veins of the cubital fossa: A meta-analysis.

Background The aim of this systematic review is to quantitatively synthesize evidence on the prevalence of superficial vein patterns in the cubital region. Method A systematic literature search was conducted through a number of electronic databases. We identified 27 studies, including 9924 arms, which met the inclusion criteria. Results Meta-analysis showed that “N” shaped arrangement type was the commonest pattern (≈44–60%) followed by “M” shaped arrangement (≈20–25%). The prevalence of “M” type and “M”-like type was significantly higher in males, whereas females showed a significant predominance of “I” or “O” type. No significant differences in various pattern types were found for laterality. The frequency of “M” type is significantly lesser in Indian and Japanese populations, but they have significantly higher frequency of “N” type. In Malay population, “I” or “O” type was significantly higher, while the brachial CV was poorly developed or missing significantly in Indian population. Conclusion This evidence-based clinical anatomy review contributes to our anatomical knowledge regarding the true prevalence of pattern types of the superficial veins in cubital region in humans and, subsequently, might help in performing safer venous access and more direct approaches to these veins, especially under emergency conditions.

The prevalence of the extensor digitorum communis tendon and its insertion variants: a systematic review and meta-analysis.

The tendons of the Extensor Digitorum Communis (EDC) are frequently injured in hand trauma. Dislocation and spontaneous rupture can also occur during the course of wrist osteoarthritis and rheumatoid arthritis. The EDC exhibits many variations including splitting of its individual slips to the medial four fingers or their absence. The aim of this systematic review is to assemble evidence about the prevalence of the EDC and its variants on the dorsum of the hand. Twenty‐four cadaveric studies met the inclusion criteria, providing data from a total of 2,005 hands. Meta‐analysis yielded the following results: (a) for EDC‐II (Index), the pooled prevalence estimates (PPEs) were 99.8, 98, 1.8, and 0.2% for the total, single, double, and triple slips, respectively; (b) for EDC‐III (Middle), the PPEs were 100, 67.7, 24.2, 6, and 0.42% for the total, single, double, triple, and quadruple slips, respectively; (c) for EDC‐IV (Ring), the PPEs were 100, 58.6, 29.1, 7.1, and 1.3% for the total, single, double, triple, and quadruple slips, respectively; (d) for EDC‐V (Little), the PPEs were 63.2, 58.5, 10.4, 0.94, and 25% for the total, single, double, triple, and common 4th–5th slips, respectively. There were no significant differences in relation to hand side. Many EDC slip variants demonstrated some interaction with ancestry. A sound knowledge of EDC variants and their prevalences is paramount for assessing and treating hand injuries and disorders. Clin. Anat. 27:1284–1290, 2014.

Tendon and neurovascular injuries of the distal radius after pinning with Kirschner wires: A meta-analysis of cadaveric studies.

Tendon and nerve structures are at risk when displaced fractures of the distal radius are pinned using K‐wires. The aim of this meta‐analysis (MA) is to examine the published evidence of such complications in cadavers. Eight studies met our inclusion criteria. The meta‐analytical results were as follows: (a) 2.87% and 30.5% tendon involvement at the radial styloid process (RSP) and the dorso‐radial area of the distal radius, respectively; (b) 3.5% and 1.1% tendon involvement when the percutaneous pinning (PP) and the limited open pinning (LOP) techniques were used, respectively; (c) 16.1% and 3.4% nerve involvement at the RSP and the dorso‐radial area of the distal radius, respectively; (d) in 35.7% the nerve was speared and in 64.3% it touched the K‐wire at the styloid area; (e) 61.3% cephalic vein involvement in the styloid area; (f) the second branch of the sensitive branch of the radial nerve (SBRN) was the closest to a wire inserted into the RSP; (g) the mean (±SD) distance between a branch of the SBRN and a styloid wire was 2.17 ± 0.82 mm. Our results for nerve and tendon injury frequencies in the RSP were close to those in clinical meta‐analytical studies, offering an excellent statistical model of evidence synthesis based on cadaveric studies to assess the frequency of such injuries in clinical practice. However, this cadaveric MA yielded more accurate data than the previously reported clinical MA in assessing the real risk of injury of such structures in the distal radius in terms of their proximity to the inserted K‐wires. Clin. Anat. 28:545–550, 2015.

Linburg–Comstock variation and syndrome. A meta-analysis

IntroductionLinburg–Comstock variation often connecting the flexor pollicis longus and flexor digitorum profundus of the index finger at a different level with significant discrepancy between clinical and cadaveric frequencies reported in the literature. Although this variation is quite prevalent, it is yet frequently unrecognized. The aim of this meta-analysis is to generate more accurate weighted frequency values of the Linburg–Comstock variation and to look for possible association with ethnicity, laterality, gender and side.MethodsA systematic literature search identified 14 studies, including 4132 forearms/hands, which met the inclusion criteria.ResultsWhile no significant difference was found for laterality, we found significantly higher Linburg–Comstock variation rate in females compared to males. Turkish population demonstrated a significantly higher crude frequency when compared to Europeans (22.2 vs. 15.2%). Hispanic population showed the highest crude frequency (34.5%), whereas the African ancestry showed the least one (8.8%).ConclusionsLinburg–Comstock variation could cause career-threatening disabilities and could complicate some hand injuries as well. This review invites future researchers to use a single nomenclature; the term “Linburg–Comstock variation” is to be used when no symptoms are present, and the term “Linburg–Comstock syndrome” in cases where the variation is symptomatic.