Differences and similarities in muscle architecture of fibularis longus and brevis-An observational descriptive cross-sectional and feasibility study.

BACKGROUND: The fibularis longus (FL) muscle is larger in volume than fibularis brevis (FB) and is therefore claimed to be the stronger evertor of the two. Clinical observation of FL and FB tendon rupture show that injury to the FB has a serious negative effect on hindfoot eversion. This implies that the FB is the stronger and more important evertor. The strength of a muscle is not purely based on its volume, and the observed discrepancy between the FB and FL may be due to differences in muscle architecture. This study compares the muscle architecture of FL with FB. METHODS: Sixteen legs from eight formaldehyde-fixed human specimens, mean age 83 (range 72-89) years, were dissected. The volume, fibre lengths and fibre pennation angles for both muscles were measured and the physiological cross-sectional area (PCSA) was calculated. RESULTS: The FL was always larger than the FB, with an individual difference in volume that varied from 1.4 to 4.6 times larger with a mean difference of 17 ml (95% CI 14-20; p < 0.001). Mean fibre lengths were 9 mm (95% CI 2-16; p = 0.015) longer in FL than in FB. The mean pennation angle was 9.6 degrees in FL and 8.8 degrees in FB, this difference was not significant (p = 0.32). The mean PCSA for FL was 3 cm2 (95% CI 2-4) larger than for FB (p < 0.001). CONCLUSIONS: With our sample set, the hypothesis that the muscle architecture can explain the clinical discrepancy between the FL and FB, was not supported. The difference in hindfoot eversion might instead depend on the different moment arms of FL and FB and the effect forefoot abduction has on hindfoot eversion.

Surgical applied anatomy: alive and kicking.

BACKGROUND: Contention exists amongst anatomists, clinicians and surgeons about how much anatomical knowledge medical students need, although what is taught should be aligned with current surgical practice. The aim of this study was to explore the scope of recent advances in applied anatomy as highlighted in the ANZ Journal of Surgery in each of the surgical specialties. METHODS: The 2018 volume of the ANZ Journal of Surgery was narrowed to 254 articles by applying the search term 'anatomy'. The main topic was extracted from each paper. The content of the paper was assessed for 'novel description' or 'novel application' of anatomical knowledge and classified accordingly. RESULTS: Most papers with an anatomical focus were from general surgery, which focused on surgical techniques, outcomes and management. Vascular surgery had the highest percentage of papers with a novel description and application of anatomy. Although cardiothoracic and paediatric surgery had no papers with a novel description of anatomy, novel applications of anatomy were a focus in each speciality. CONCLUSION: The trend towards novel applications of anatomical knowledge in all surgical specialties should encourage medical schools to shape their anatomy curricula in tandem with such advances as they evolve. The high proportion of novel applications and descriptions of anatomy in general surgery indicates continued growth as a benchmark of anatomical understanding. Vascular surgery's proportion of novel application and description of anatomy may change the way students will learn vascular anatomy to incorporate endovascular, radiologically based approaches.

Lengthening of the gastrocnemius-soleus complex: an anatomical and biomechanical study in human cadavers.

BACKGROUND: Lengthening of the gastrocnemius-soleus complex is frequently performed for equinus deformity. Many techniques have been described, but there is uncertainty regarding the precise details of some surgical procedures. METHODS: The surgical anatomy of the gastrocnemius-soleus complex was investigated, and standardized approaches were developed for the procedures described by Baumann, Strayer, Vulpius, Baker, Hoke, and White. The biomechanical characteristics of these six procedures were then compared in three randomized trials involving formaldehyde-preserved human cadaveric lower limbs. After one of the lengthening procedures was performed, a measured dorsiflexion force was applied across the metatarsal heads with use of a torque dynamometer. Lengthening of the gastrocnemius-soleus complex was measured directly, by measuring the gap between the ends of the fascia or tendon. RESULTS: The gastrocnemius-soleus musculotendinous unit was subdivided into three zones. In Zone 1, it was possible to lengthen the gastrocnemius-soleus complex in either a selective or a differential manner-i.e., to lengthen the gastrocnemius alone or to lengthen the gastrocnemius and soleus by different amounts. The procedures performed in this zone (Baumann and Strayer procedures) were very stable but were limited with regard to the amount of lengthening achieved. Zone-2 lengthenings of the conjoined gastrocnemius aponeurosis and soleus fascia (Vulpius and Baker procedures) were not selective but were stable and resulted in significantly greater lengthening than Zone-1 procedures (p < 0.001). In Zone 3 (Hoke and White procedures), lengthenings of the Achilles tendon were neither selective nor stable but resulted in significantly greater lengthening than Zone-1 or 2 procedures (p < 0.001). CONCLUSIONS: Surgical procedures for the correction of equinus deformity by lengthening of the gastrocnemius-soleus complex vary in terms of selectivity, stability, and range of correction. Procedures for the correction of equinus deformity have different anatomical and biomechanical characteristics. Clinical trials are needed to determine whether these differences are of clinical importance. It may be appropriate for surgeons to select a procedure involving the zone best suited to the clinical needs of a specific patient.

Anatomy and pathophysiology of the pleura and pleural space.

Pleural effusions are most often secondary to an underlying condition and may be the first sign of the underlying pathologic condition. The balance between the hydrostatic and oncotic forces dictates pleural fluid homeostasis. The parietal pleura has a more significant role in pleural fluid homeostasis. Its vessels are closer to the pleural space compared with its visceral counterpart; it contains lymphatic stomata, absent on visceral pleura, which are responsible for a bulk clearance of fluid. The diagnosis and successful treatment of pleural effusions requires a mixture of imaging techniques and pleural fluid analysis.

Biomechanics of medial hamstring lengthening.

BACKGROUND: Medial hamstring lengthening is frequently used to correct contractures in neuromuscular conditions such as cerebral palsy. Surgical techniques vary considerably and little is known about the lengthening characteristics of muscle-tendon-units after surgical intervention. METHODS: A randomized trial was performed on paired cadaver medial hamstring muscle-tendon-units comparing 'High' (proximal) versus 'Low' (distal) lengthening procedures. The paired muscle-tendon-units were subjected to tensile testing utilizing an Instron® (Instron Corporation, Canton, MA, USA) machine under controlled conditions. Prior to tensile testing, the paired semitendinosus and paired gracilis received either high or low intramuscular tenotomy. Load (N) versus displacement (mm) was recorded continuously for each test. The difference in lengthening and load at failure for intact and surgical simulation muscle-tendon-units was recorded and compared with paired t-tests. RESULTS: Both low and high lengthenings increased the amount of lengthening achieved compared with intact controls and the lengthening was achieved at lower applied load. Low intramuscular tenotomy of the semitendinosus resulted in a 30% greater lengthening when compared with high intramuscular tenotomy. For the gracilis muscle, the low intramuscular tenotomy achieved 39% greater lengthening than the high intramuscular tenotomy and these differences were significant. CONCLUSION: Biomechanical testing of formalin-preserved human cadaveric medial hamstring muscle-tendon-units confirms that it is possible to achieve lengthening in continuity following an intramuscular tenotomy or fascial striping procedure. The site of the surgical procedure (high versus low) results in a different effect on the lengthening characteristics, dictated by the anatomy of the particular muscle-tendon-unit.

The effects of intramuscular tenotomy on the lengthening characteristics of tibialis posterior: high versus low intramuscular tenotomy.

BACKGROUND: Lengthening of soft-tissue contractures is frequently required in children with a wide variety of congenital and acquired deformities. However, little is known about the biomechanics of surgical procedures which are commonly used in contracture surgery, or if variations in technique may have a bearing on surgical outcomes. We investigated the hypothesis that the site of intramuscular tenotomy (IMT) within the muscle-tendon-unit (MTU) of the tibialis posterior (TP) would affect the lengthening characteristics. METHODS: We performed a randomized trial on paired cadaver tibialis posterior muscle-tendon-units (TP-MTUs). By random allocation, one of each pair of formalin-preserved TP-MTUs received a high IMT, and the other a low IMT. These were individually tensile-tested with an Instron(®) machine under controlled conditions. A graph of load (Newtons) versus displacement (millimetres) was generated for each pair of tests. The differences in lengthening and load at failure for each pair of TP-MTUs were noted and compared using paired t tests. RESULTS: We found 48% greater lengthening for low IMT compared to high IMT for a given load (P = 0.004, two tailed t test). Load at failure was also significantly lower for the low IMT. These findings confirm our hypothesis that the site of the tenotomy affects the amount of lengthening achieved. This may contribute to the reported variability in clinical outcome. CONCLUSIONS: Understanding the relationship between tenotomy site and lengthening may allow surgeons to vary the site of the tenotomy in order to achieve pre-determined surgical goals. It may be possible to control the surgical "dose" by altering the position of the intramuscular tenotomy within the muscle-tendon-unit.

Anomalies of the flexor carpi ulnaris: clinical case report and cadaveric study.

Flexor carpi ulnaris (FCU) is an ever-present muscle of the anterior flexor compartment of the forearm. Variations of FCU are uncommon, with additional slips or heads of muscles described, and only one reported case of an accessory muscle. We describe a unique clinical case report in which an accessory FCU was identified and describe the findings of 5,000 cadaveric dissections of the forearm, performed as part of an ongoing institutional study of anatomical variations. An aberrant accessory forearm flexor muscle was identified incidentally at the wrist during surgery for an anterior interosseous to ulnar nerve transfer for management of ulnar nerve palsy. This muscle was seen running superficial to the ulnar nerve and radial to the FCU proper, arising from the common flexor origin and inserting at the triquetral carpal bone. This was therefore suitably acknowledged as an "accessory FCU". The anomaly was identified as bilateral using ultrasound imaging, and was found to be anomalously innervated by the median nerve with nerve conduction studies. A subsequent review of 5,000 cadaveric dissections of the forearm did not identify any such variations related to FCU, despite identifying a range of variations of the other forearm flexor musculature. While the scarcity of this anomaly is thus highlighted, consideration of an accessory FCU, and its aberrant innervation is important in a range of surgical approaches.

The subpectoral pacemaker implant: it isn't what it seems!

The traditional pulse generator implantation site lies subcutaneous on the fascia of the pectoralis major muscle. This article describes a subpectoral pocket approach, which on anatomic investigation is actually "intrapectoral" and offers a much improved cosmetic result with the potential advantage of less erosion. In the authors' experience with over 1000 initial pacemaker implants and pulse generator replacements, the potential concerns of neurovascular and muscular damage have not been realized. There has been no pulse generator damage from the ribs, serious loculated hematomas, or unusual postoperative or chronic pain. From experience with pulse generator recalls, the replacement procedure has not been significantly more difficult than with the subcutaneous approach. The intrapectoral approach has now become the authors' routine in patients without significant adipose tissue overlying the pectoralis major muscle.

Anatomy of the pudendal nerve and its terminal branches: a cadaver study.

BACKGROUND: This study documents the anatomy of the pudendal nerve, which has a major role in maintaining faecal continence. Unexpected faecal incontinence can develop following perineal surgery even when the anal sphincters are not damaged. In addition, injury to the pudendal nerve might be encountered during pelvic procedures such as a sacrospinous colpopexy. METHODS: An anatomical study on 28 cadavers was conducted to examine the course of the pudendal nerve and its branches in the perineum. RESULTS: In five of the 28 cadavers dissected (four male, one female), a nerve plexus was found within the ischiorectal fossa in close proximity to the anal sphincters. The plexus received contributions from interconnecting branches of the inferior rectal and perineal nerves to innervate the external anal sphincter. In 11 of the 28 cadavers (five female, six male) an additional nerve arose from the medial aspect of the pudendal nerve at the level of the sacrotuberous and sacrospinous ligaments. This nerve continued distally and gave several branches to the perineum and the levator ani muscle. CONCLUSION: A sound knowledge of the anatomical variations of the pudendal nerve and its branches is essential for all surgeons operating in the perineal region.