From formalin to Thiel embalming: What changes? One anatomy department's experiences.

In 2009, the Centre for Anatomy and Human Identification started Thiel embalming on a small scale to assess (i) the suitability for our current teaching in which long-lasting dissection courses are key, (ii) the potential for new collaborations and activities, and (iii) the practical implications of changing our embalming method from formalin to Thiel. Twenty six Thiel-embalmed cadavers have been used for dissection by staff and students on a taught MSc course, as a model for clinical and surgical training, and increasingly as a model for evaluation of new medical devices and procedures. Our experiences with dissection were mostly positive especially for teaching the musculoskeletal system. Internal organs handle differently from formalin-fixed organs and dissection manuals need to be adjusted to reflect this. Durability of the cadavers was not an issue, though changes are seen over time due to gradual fluid loss. We have started new collaborations related to postgraduate anatomy teaching and advanced training in surgical and clinical skills. In general, feedback is very positive and demand for cadavers outstrips our current limited supply. Thiel-embalmed cadavers were found to provide a unique opportunity for evaluation of medical products especially in areas where no suitable alternative model is available, and without the complications associated with clinical testing. This has resulted in new collaborations and research projects. As a result Thiel-embalmed cadavers are used for longer and for more activities than formalin cadavers: this requires changes in our procedures and staff roles.

Translation of sonoelastography from Thiel cadaver to patients for peripheral nerve blocks.

Ultrasound guidance is now common in regional anaesthesia practice, but remains limited by poor visibility of the needle tip and poor quantification of local anaesthetic spread. Sonoelastography based on tissue compression is a technique depicting tissue strain. Hitherto used largely for tumour diagnosis, we used it in both Thiel embalmed cadavers and two patients receiving interscalene and femoral blocks to observe changes in tissue strain during local anaesthetic injection. The primary aim of our study was to measure the area under the curve (weighted for time) of the strain pattern in Thiel perineural tissue when using a range of volumes of embalming fluid (0.25, 0.5, 1, 2.5, 5 and 7.5 ml) for interscalene and femoral blocks using sonoelastography. Our secondary aims were to evaluate static images of anatomy and videos of needle insertion and perineural injection using combined B-Mode ultrasound and sonoelastography. Independent raters assessed the anatomy and spread using a 7-point Likert scale, ranked from extremely poor to extremely good. We performed 83 blocks in cadavers. Concordance between both raters was good, with weighted Kappa (95% CI) 0.66 (0.61-0.71). The characteristics of spread were similar with both interscalene and femoral block; spread increased with injectate volume up to 1 ml. Analysis of variance showed differences in spread between injection volumes (p = 0.009), but not between regional blocks (p = 0.05). Post-hoc analysis showed greater spread with 1 and 2.5 ml volumes compared with 0.25 ml. In patients, visibility of strain during injection was better with sonoelastography than with B-Mode ultrasound and showed a dose response from 1 to 5 ml volumes of local anaesthetic. Colour strain recognition using sonoelastography offers the ability to differentiate between nerve and surrounding tissue during local anaesthetic injection by improving visibility of spread (p = 0.04).

A comparison of Thiel and formalin embalmed cadavers for thyroid surgery training.

BACKGROUND: The European Working Time Directive has increased the need for surgical skills training which does not involve patients. Recent changes in the anatomy legislation now make it possible to perform surgical procedures on human cadavers. Standard formalin embalming, however does not provide a very realistic model and alternative approaches, such as Thiel soft-fix embalmed cadavers, should be explored and evaluated. METHODS: Two formalin and 3 Thiel embalmed cadavers were used at a senior trainee and consultant course in thyroid surgery. The 12 participants (8 trainees and 4 consultants) were asked to score 15 aspects, such as quality of different tissues, for each type of cadaver. Some of these aspects were specific to thyroid surgery, however many are equally applicable to other specialties. RESULTS: All participants rated the Thiel embalmed cadavers better or equal for all aspects. Of the 180 pairs of scores 33 were excluded, 10 were equal for formalin and Thiel, while in the remaining 137 Thiel scored better. The preference was particularly pronounced in aspects that require flexibility of tissues such as flap raising. CONCLUSIONS: Thiel embalmed cadavers provide a more realistic model for training of thyroid surgical skills; this is expected to be similar for many other types of surgery.

An anatomical study of the superficial palmar communicating branch between the median and ulnar nerves.

The palmar communicating branch between the median and ulnar nerves was investigated in 98 hands with the aim of outlining its most common branching patterns and describing its relationship to well-defined anatomical landmarks, including the bistyloid line, wrist crease and flexor retinaculum. Five branching patterns were identified and classified based on their proximal and distal attachments. The palmar communicating branch was found to lie between 26%-79% of the total distance between the metacarpophalangeal joint of the long finger and the wrist crease, and 35%-75% of the total distance between the metacarpophalangeal joint of the long finger and the middle of the bistyloid line. With the aid of the morphometric indices obtained from this study, a risk area where the palmar communicating branch is most likely to be found is outlined. Knowledge of the branching patterns and location of the palmar communicating branch can help clinicians to better assess variations in the patterns of sensation, preserve the nerve during surgical interventions to the palm and better assess post-operative complications involving the branch.

Surgical simulation flexor tendon repair using Thiel cadavers: a comparison with formalin embalmed cadavers and porcine models.

UNLABELLED: The aim of this study was to compare Thiel-embalmed cadavers with formalin-embalmed cadavers and porcine models in the surgical simulation repair of a Zone II flexor tendon division. Nine participants were recruited to the study. The models were assessed using a five-point scale. Assessment was divided into tissue quality, surgical approach and identification of structures. Thiel cadavers rated consistently higher compared with the formalin and porcine models (mean 37 SD 2, 22 SD 6 and 23 SD 5, respectively). Thiel cadavers recorded an average tendon glide of 21 mm SD 5, formalin cadavers 2 mm SD 2 and the porcine model 6 mm SD 2. We have demonstrated the benefit of Thiel embalming, with flexibility of tissues allowing testing of the repair of a flexor tendon in a realistic anatomical model. LEVEL OF EVIDENCE: Level V.

Blood supply of the Achilles tendon.

The Achilles tendon is one of the most common sites of injury and rupture as a result of overuse. Evidence suggests that the pathogenesis of rupture could involve the pattern of its blood supply. With use of angiographic and histological techniques, the blood supply of the Achilles tendon was investigated in 12 human cadaveric specimens. Angiography confirmed Mayer's 1916 finding that the blood supply to the tendon is from three areas: the musculotendinous and osseotendinous junctions and the paratenon, with the posterior tibial artery providing the major contribution. However, qualitative and quantitative histological analyses in this study showed that the Achilles tendon has a poor blood supply throughout its length, as determined by the small number of blood vessels per cross-sectional area, which do not in general vary significantly along its length. In light of these findings, it is suggested that poor vascularity may prevent adequate tissue repair following trauma, leading to further weakening of the tendon.

Gait following lateral collateral ligament repair.

Kinetic parameters of gait were examined in two groups of individuals who had sustained trauma of the lateral collateral ligament of the ankle. One group were diagnosed as having second-degree sprains and were immobilized in a plaster cast for 2 weeks (conservative treatment), while the other group had third-degree sprains and underwent surgical repair prior to being immobilized for 6 weeks in a plaster cast. Following removal of the cast subjects received similar programmes of physical therapy which were designed to mobilize the joint, strengthen the muscles, and improve proprioception. Six months after the initial ankle trauma gait patterns were recorded and analyzed. Few differences were observed between the two groups of subjects in either the pattern or the magnitude of the three orthogonal ground reaction forces. Furthermore, within each group no differences were observed between the sound and injured legs; however, there were differences between the corresponding legs of the two treatment groups.

Morphology of the plantar calcaneocuboid ligaments.

The plantar calcaneocuboid ligaments have various configurations and are referred to in the literature by different names. The aims of this study were to classify the form and attachments of the plantar calcaneocuboid ligaments and to determine their dimensions to describe their morphology. The plantar aspects of 59 cadaver feet were dissected to expose the associated ligaments. The long and short plantar ligaments showed several structural variations of shape, band number, and attachments. The variations that were seen have led to confusion in the literature, which needs to be resolved. A new nomenclature is suggested based on the observed morphology. These findings agree with previous reports, and data are also presented that describe the shapes of the ligaments.

Anatomy of the collateral ligaments of the human ankle joint.

Damage to the collateral ligaments of the ankle is relatively common, particularly the lateral ligaments; therefore, it is important to be aware of the detailed anatomy and frequency of variation of the individual ligaments. Only two reports of collateral ligaments dimensions were found in the literature, neither of which considers all of the individual components of the collateral ligament complex. Osteoligamentous preparations of the collateral ligaments of 40 ankles from 20 cadavers of European Caucasian origin were studied, from which mean values for the length and width of the individual components were determined, together with their frequency of occurrence. For the collateral ligaments of the ankle as a whole, the ligamentous dimensions determined in this study are similar to those reported previously. The data presented in this study are, therefore, a valuable addition to the small pool of data that exists concerning the dimensions of the collateral ligaments of the human ankle joint. These data may be of value when considering surgical repair or reconstruction of traumatized collateral ligaments, especially because any undue foreshortening of the ligaments may reduce the range of motion possible at either the ankle or subtalar joints, or both. It is possible that in extreme cases, such a reduction in the range of motion may modify gait patterns and the transmission of stresses across the joints of the foot and lower limb.

The medial collateral ligaments of the human ankle joint: anatomical variations.

This study aimed to investigate anatomical variations within the medial collateral ligament complex of the human ankle joint. Osteoligamentous preparations of 40 ankles from 20 cadavers were studied. Six different component bands of the medial collateral ligament complex were observed: four superficial bands (tibiospring, tibionavicular, superficial posterior tibiotalar, and tibiocalcaneal ligaments), of which only the tibiospring and tibionavicular ligaments were constant, and two deep bands (deep posterior tibiotalar and deep anterior tibiotalar ligaments), of which only the deep posterior tibiotalar ligament was constant. No pattern was observed in the distribution of additional bands. A consistent and universally accepted system for naming the various bands of the medial collateral ligament is necessary to enable easy and accurate comparisons between studies. We suggest that this system should be based on the attachments of the ligaments.

A new clinical test for radial tunnel syndrome--the Rule-of-Nine test: a cadaveric study.

PURPOSE: Radial tunnel syndrome refers to pain on the lateral aspect of the forearm as a result of compression of the posterior interosseous nerve within a tunnel with specific anatomical boundaries. Diagnosis of the condition is difficult because of its close association with lateral epicondylitis, which warrants different methods of treatment. Based on a cadaveric study, a new clinical test, the Rule-of-Nine test, is proposed to improve the diagnostic accuracy in radial tunnel syndrome. The test involves constructing 9 equal squares on the anterior aspect of the forearm and noting those squares where tenderness can be elicited. METHODS: 19 upper limbs were dissected to delineate the path of the posterior interosseous nerve through the radial tunnel, and the relationship of the path of the nerve with the 9 squares. RESULTS: A consistent mapping of the posterior interosseous nerve to the lateral column of 3 squares was observed. CONCLUSION: The Rule-of-Nine test is proposed as a reliable method of diagnosing radial tunnel syndrome.

Assessing the variability of injectate distribution following carpal tunnel injection--a cadaveric study.

This anatomical study was designed to assess the distribution of a solution (injectate) made up using local anesthetic, steroid and dye into the carpal tunnel using a commonly used injection technique. Dissections were undertaken in 29 embalmed cadaveric wrists. The cadaveric specimens were dissected 24 hours after injection to observe the effect of time on diffusion patterns in both superficial and deep planes. Eighteen of the 29 specimens showed the presence of the injectate in the superficial plane and three preferential patterns of distribution were noted in the deep plane: free in the carpal tunnel, exclusively in the tendon sheath and mixed. This is the first study investigating the delayed diffusion pattern of injectate in the carpal tunnel and illustrates its variability. The findings of variable degree of superficial diffusion and different patterns of intracarpal spread help to offer some explanation regarding the variability of the response following carpal tunnel injection.

The relationship between the saphenopopliteal junction and the common peroneal nerve: a cada-veric study.

OBJECTIVES: The variable anatomy of the short saphenous vein (SSV) and the potential failure to identify the saphenopopliteal junction (SPJ) contribute to an increased risk of damage to the common peroneal nerve (CPN) during surgical exploration. The aim of the present study was to determine the variation of the SPJ, its relationship to the CPN, and the relationship of both SPJ and CPN to defined anatomical landmarks. METHODS: Measurements of the distance between the SPJ and CPN, and the defined anatomical landmarks (fibula head, lateral joint space, lateral femoral epicondyle), were undertaken on 30 cadaveric limbs following careful dissection of the popliteal fossa. RESULTS: The level of SPJ termination was classified as low (below), normal (within 100 mm above) and high (more than 100 mm above), the lateral femoral epicondyle. Of the 30 limbs dissected, 70% of SPJs were normal, 23% low and 7% high. Direct measurement from the SPJ to anatomical landmarks showed a higher interquartile range (IQR) in low compared with normal terminations; however, the vertical distance from the SPJ to the fibula head showed an increase in IQR from low to normal terminations (7.1-14.2). The mean distances between the SPJ and CPN in low and normal terminations were 23.3 and 16.7 mm, respectively. Comparison of the IQR showed values very similar to low terminations having a slightly higher IQR compared with normal terminations (7.15-6.0). CONCLUSION: Significant anatomic variation was observed in the termination of the SSV, with 67% located within 66 mm above the lateral femoral epicondyle. The risk of damaging the CPN during saphenopopliteal ligation may be higher for SPJs located above the lateral femoral epicondyle because of the proximity of the two structures and variability of SPJ.

Foot pressure patterns during gait.

Peak pressure and temporal parameters of foot function were determined in 21 men and 11 women; few differences between men and women in any of the parameters were observed, either when walking barefoot or when wearing shoes. However, significant differences were observed when barefoot and shod walking were compared. The main influence of shoes appears to be in modifying the behaviour of the forefoot, by changing the pressure distribution across the metatarsal heads and increasing the contact times for the toes. The implications of such changes are discussed. Intersubject variability in the pattern and magnitude of the peak pressure distributions under the foot, which appear to be consistent in both the short and long term, may prove to be of importance in the clinical environment, by providing an individual baseline from which change can be measured. A new measure, the pressure-time integral, could be a more valuable single measure than either the peak pressure or the temporal parameters.

Proximal femoral fracture. Range of hip motion as a predictor of fracture type.

A cadaveric study has shown that the femoral neck impinges on the posterior part of the acetabulum at an average of 54.5 degrees external rotation and that an intracapsular fracture can be reproduced by an impact load onto the greater trochanter with the hip in external rotation. A clinical study of hip rotation of the contralateral uninjured hip in 100 patients after proximal femoral fracture was done to compare the degree of external rotation between extracapsular and intracapsular fracture. The mean value for intracapsular fracture was 62.1 degrees and for extracapsular fracture was 48.9 degrees. A retrieval study of the femoral head and neck from patients undergoing hip hemiarthroplasty for intracapsular fracture showed a consistent pattern of fracture with posterior comminution suggesting neck impingement. Previous work has suggested that an intracapsular fracture occurs during a fall when external hip rotation thrusts the femoral neck against the posterior margin of the acetabulum. The current investigation would support this hypothesis and suggests that the natural degree of external hip rotation is a predictor of fracture type.

Human intervertebral disc: structure and function.

This review begins with a brief introduction in which the development, blood supply and innervation of the intervertebral disc is considered, particularly as these may influence the following sections on structure and function. The three regions within the disc--that is, the nucleus pulposus, annulus fibrosus, and cartilage end plates--are considered in some detail. There appears to be no distinct border between the central nucleus pulposus and the outer annulus fibrosus, the main difference being in their fibrous structure. The fluid space is important in the nutrition of the disc, showing plastic deformation and recovery characteristics. The structural elements, both macroscopically and microscopically, together with the biochemical elements, are intimately related to function. The intervertebral disc should not be though of as a homogeneous and static structure; it has a heterogeneous composition and responds dynamically to applied loads. Neither should it be considered as an isolated structure because it interacts with the vertebral bodies, together constituting the vertebral unit. Furthermore, changes within the disc can, and do, have dramatic effects on vertebral column kinematics. The intervertebral disc is not inactive; it is capable of self-maintenance; in injury it can repair itself and has considerable regenerative properties.

The influence of moving auditory fields on postural sway behaviour in man.

Postural sway behaviour was assessed, using a standard biomechanical measuring platform, in 30 young subjects (15 men, 15 women) during 60 s of erect standing in various combinations of visual input and moving auditory fields. The sway parameters investigated were mean lateral, antero-posterior, radius and velocity of sway, the area within the sway profile and the length of the sway path. The findings support the view that moving auditory fields have a destabilising influence on postural sway behaviour, and suggest that under the appropriate conditions postural sway can be "driven" by the auditory environment.

Auditory and visual interactions in postural stabilization.

The interaction and subsequent interpretation of sensory feedback from different modalities are important determinants in the regulation of balance. The importance of sound in this respect is not, as yet, fully understood. The aim of the present study was to determine the interaction of specific auditory frequencies and vision on postural sway behaviour. The frequencies employed represent the geometrical mean of 23 of the 25 critical bandwidths of sound, each presented at two loudness levels (70 and 90 phones). Postural sway was recorded using a biomechanical measuring platform. As expected vision had a highly significant stabilizing effect on most sway parameters. The frequency of the sound, however, appeared to influence the regulation of anteroposterior sway, while increasing loudness tended to increase mediolateral sway. At some frequencies the sound appeared to compensate for the lack of visual feedback. The interaction of sound and vision, particularly in combinations that lead to increased sway behaviour, may have implications in the occurrence, and possible prevention, of industrial accidents.