Viscoelastic properties of the human A2 finger pulley.

INTRODUCTION: Biomechanical evaluation of the viscoelastic properties tissue deformation, stiffness, and maximum breaking load of the human A2 pulley. We hypothesized that the A2 pulleys of index, middle, and ring fingers exhibit no difference regarding the aforementioned biomechanical parameters. METHODS: Forty-one A2 pulleys of 14 upper extremities (8 body donors) were assessed. Cyclic and load-to-failure testing were performed. The biomechanical parameters tissue deformation during cyclic and load-to-failure testing, stiffness, and maximum breaking load were determined. RESULTS: No significant differences between the fingers could be detected regarding the biomechanical parameters. A significant negative correlation could be detected between stiffness and deformation of the pulley. Significant positive correlations could be identified between stiffness and maximum breaking load and between maximum breaking load and deformation of the pulleys. CONCLUSIONS: Assessment of the viscoelastic properties of the A2 finger pulley promotes precise diagnosis of pulley lesions and will help to optimize treatment.

[Revision surgery for carpal and cubital tunnel syndrome]. / Revisionseingriffe beim Karpal- und Kubitaltunnelsyndrom.

BACKGROUND: Carpal tunnel syndrome, a compressive neuropathy of the median nerve at the wrist and cubital tunnel syndrome, a compressive neuropathy of the ulnar nerve at the elbow, are the two most common peripheral nerve compression syndromes. Chronic compressive neuropathy of peripheral nerves causes pain, paraesthesia and paresis. Treatment strategies include conservative options, but only surgical decompression can resolve the mechanical entrapment of the nerve with proven good clinical results. However, revision rates for persistent or recurrent carpal tunnel syndrome is estimated at around 5% and for refractory cubital tunnel syndrome at around 19%. Common causes for failure include incomplete release of the entrapment and postoperative perineural scarring. THERAPY: Precise diagnostic work-up is obligatory before revision surgery. The strategy of revision surgery is first complete decompression of the affected nerve and then providing a healthy, vascularized perineural environment to allow nerve gliding and nerve healing and to avoid recurrent scarring. Various surgical options may be considered in revision surgery, including neurolysis, nerve wrapping and nerve repair. In addition, flaps may provide a well vascularized nerve coverage in the case of recurrent carpal tunnel syndrome. In the case of recurrent cubital tunnel syndrome, anterior transposition of the ulnar nerve is mostly performed for this purpose. RESULTS: In general, revision surgery leads to improvement of symptoms, although the outcome of revision surgery is less favourable than after primary surgery and complete resolution of symptoms is unlikely.

[Revision surgery after failed (partial-) arthrodesis of the wrist]. / Revisionen nach fehlgeschlagenen (Teil­)Versteifungen am Handgelenk.

(Partial) arthrodeses of the wrist have been proven cornerstones to treat many lesions for decades, especially in the case of revision surgery. Four-corner, scapho-trapezo-trapezoidal (STT), radio-scapho-lunate (RSL) and total wrist fusions are very common techniques in hand surgery. However, even these proven surgical procedures have significant non-fusion rates. Prior to revising a failed arthrodesis, it is essential to analyse the latter failure precisely. A technically adequate revision is only feasible when based on a correct and meticulous analysis. The understanding of the biological processes and technical aspects of the implants are the basis for solving this issue.

[Anatomy of the trapeziometacarpal joint in the context of arthroplasty]. / Anatomie des Daumensattelgelenks unter Berücksichtigung der Endoprothetik.

The thumb has a crucial role in the hand due to its position with regard to the fingers. The CMC-1 joint enables an extraordinary range of motion, since its geometry allows for opposition. The former joint may often succumb to osteoarthritis because a great range of motion in combination with large forces, small contact areas, and thorough usage are always present. Joint replacement is challenged by the great range of motion based on the necessary joint stability and the demand for sufficient pain reduction. This review highlights the anatomy of the CMC-1 joint with regard to joint preplacement solutions.

[Metacarpophalangeal joint replacement]. / Der Gelenkersatz der Fingergrundgelenke.

BACKGROUND: Arthroplasty of metacarpophalangeal (MCP) joints is crucial for patients with rheumatoid arthritis. Motion preserving therapies are mandatory for this joint, since loss of function of the MCP joint is detrimental. Many protheses or spacers have been introduced over the last 80 years, but most of them have been dismissed due to major complications. CURRENT PROCEDURES: Since the 1960s the Swanson spacer has been established as the reference standard for motion preserving procedures of the finger MCP joints. High fracture rates of the spacer do not seem to limit function and patient satisfaction after all. Current long-term studies show at least promising results for pyrolytic carbon protheses with respect to range of motion, survival, and revision rates in comparison to the Swanson spacer.

[Anatomy and pathobiomechanics of the scaphoid]. / Anatomie und Pathobiomechanik des Skaphoids.

Among the carpal bones the scaphoid (Os scaphoideum) is the most important. The most frequent fracture of the carpus is a fracture of the scaphoid bone. The frequently occurring absence of healing of these fractures as well as unhealed ruptures of the ligament complex between the scaphoid and lunate, lead to the most severe biomechanical and thus the most severe clinical changes of the wrist. The detailed anatomy of the scaphoid, blood flow, ligament attachments, injury mechanisms and pathobiomechanics are described and illustrated.

[Defect coverage of fingers and thumb : Indications and treatment]. / Defektdeckung an den Fingern und am Daumen : Indikation und Therapie.

Due to the exposure of the hands in the daily routine, defect wounds of the hand are common. The injury severity varies and ranges from small fingertip defects to large soft tissue lesions with exposed tendons, nerves and vessels. The complete extent of the soft tissue defect is often only recognizable after meticulous debridement. A considerable variety of techniques for defect coverage are available to the surgeon but the actual challenge is to select the most appropriate procedure which will result in the smallest possible residual defect. This review article presents the diagnostic approaches to soft tissue defects of the hand and current treatment options.

[The fibrous skeleton of the hand : Changes with Dupuytren's contracture]. / Das fibröse Skelett der Hand : Veränderungen bei der Dupuytren-Kontraktur.

The exact knowledge of the anatomy of the fibrous skeleton of the hand is an absolute prerequisite for any treatment of Dupuytren's disease. The fibrous skeleton does not only include the palmar aponeurosis, but also numerous retinacula cutis, which are not found in current anatomy books. Here, eponyms facilitate the otherwise difficult and over-pronounced names of the fiber systems. Skoog, Legueu and Juvara, Gosset, Grapow, Grayson, Cleland, Thomine, and Barton are the most important. This systematic review of the fibers and strands is designed to help reduce iatrogenic complications.

[Cubital tunnel syndrome : Diagnostics and therapy]. / Kubitaltunnelsyndrom : Diagnostik und Therapie.

Cubital tunnel syndrome is the second most common nerve compression syndrome observed in the upper extremity. Mechanical irritation of the ulnar nerve is also found in the upper and the lower arm even though cubital tunnel syndrome is documented most of the time. Apart from clinical examination electrophysiological testing is the most important contributor to the therapy decision. Depending on the clinical manifestation conservative treatment with elbow splinting may be appropriate. In the event of persistent or advanced nerve irritation surgical decompression may be the sensible intervention. Open or endoscopically assisted in situ decompression is currently recommended as the primary intervention while anterior transposition of the ulnar nerve is recommended for revision surgery.

[Distal radius fracture of the adult : Diagnostics and therapy]. / Distale Radiusfraktur : Diagnostik und Therapie beim Erwachsenen.

Fractures of the distal radius are very common. The majority of patients are elderly females. High impact trauma are often responsible for fractures in young men. Clinical and radiological diagnostics, including computer-assisted tomography (CAT) scan, are generally sufficient. The indication for conservative treatment is still recommended for specific fracture patterns. Application of palmar locking plates after open reduction proved to be efficacious for the majority of fracture patterns. Furthermore, precise detection and treatment of concomitant lesions are mandatory in order to prevent complications.

[(Partial) fusion of the wrist : Indications and surgical procedures]. / (Teil­)Arthrodesen am Handgelenk : Indikationen und chirurgische Therapien.

Carpal bone fusions for secondary reconstruction are still indispensable despite state of the art diagnostic tools and modern treatment techniques for wrist lesions. The former fusions stabilize the wrist and enable sufficient residual carpal mobility. Pain can be reduced significantly by arthrodesis of destroyed joints and the progress of osteoarthritis may be stopped or delayed. This review presents commonly used fusions with their inherent indications, contraindications and complications.

Evaluation of biomechanical properties: are porcine flexor tendons and bovine extensor tendons eligible surrogates for human tendons in in vitro studies?

INTRODUCTION: Porcine flexor tendons, bovine extensor tendons, and human (semitendinosus) tendons are frequently used as substitutes for human ACL grafts in biomechanical in vitro studies. This study compares the biomechanical properties and structural differences of these tendons. MATERIALS AND METHODS: In this biomechanical study, fresh-frozen porcine flexor tendons, bovine extensor tendons, and human semitendinosus tendons were used (n = 36). The tendons were mounted in a uniaxial testing machine (Zwick/Roell) with cryo-clamps, leaving a 60 mm tendon part free between the two clamps. Specimens have been loaded to failure to evaluate the biomechanical parameters stiffness, yield load, and maximum load. A Total Collagen Assay Kit was used to detect differences in the total collagen type I concentration (n = 30). A one-way ANOVA was performed to detect differences in the means. The significance level was set at p < 0.05. RESULTS: There were no significant differences in the stiffness between the groups (bovine 194 ± 43 N/mm, porcine 211 ± 63 N/mm, and human cadaveric 208 ± 58 N/mm). The yield and maximum loads were high (>1000 N) in all groups, but they were significantly increased in both animal specimens (means of 1681-1795 N) compared with human cadaveric specimen (means of 1289-1406 N; p < 0.01). No difference in the collagen type I concentration was detected (N.S.). CONCLUSION: Porcine flexor and bovine extensor tendons are eligible substitutes with similar stiffness and high failure loads compared with human cadaveric semitendinosus tendons in in vitro studies.

[Anatomy and biomechanics of the scaphoid]. / Anatomie und Biomechanik des Kahnbeins.

The scaphoid is biomechanically and clinically of great importance for function of the wrist. In the literature, its anatomy and biomechanics are clearly underrepresented as well as underestimated. In the following review the scaphoid will be presented in more detail, according to recent information and findings. Not only will the origin of the name and the history of previous names, such as cotyloid or navicular, be introduced, but also for the first time in medical literature the significant phylogeny and ontogeny of the scaphoid will be shown. Moreover, the clinically very important blood supply, the ligaments of the scaphoid and relevant biomechanical details will be described.

[Malformations of hand and forearm : Conspicuous postpartum]. / Fehlbildungen an Hand und Unterarm : Postpartal auffallend.

Many congenital malformations of the hand and forearm, e. g. polydactyly, thumb duplication, syndactyly and radial aplasia, are already evident at birth and newborns are promptly referred to specialized departments. In contrast, orthopedic surgeons are often confronted with malformations of the hand and forearm, which gradually become clinically conspicuous during growth. This review article focuses on these specific malformations, which regularly upset the patients in practice and in most cases the parents even more so. In addition to the diagnostics and differential diagnostics, the conservative and surgical treatment options are presented.

[Treatment of instability of the metacarpophalangeal and trapeziometacarpal joints of the thumb]. / Behandlung der Instabilität des Daumengrund- und des Daumensattelgelenks.

Restoration of stability of the thumb represents an enormous gain of function for the patient and can be achieved by arthrodesis or ligament reconstruction. Ligament reconstruction should only be performed if good stability and mobility and a pain-free grip can also be achieved. In every case surgery must protect the delicate soft tissues and should be based on a profound knowledge of the anatomical and biomechanical circumstances. Instability of the trapeziometacarpal joint is rare but metacarpophalangeal joint instability (ulnar, palmar and radial) is relatively frequent. For both conditions arthrodesis is the most frequently used and easier surgical procedure. Ligament reconstruction is more difficult to perform but can maintain the mobility of these joints.

[Fractures of the proximal interphalangeal joint: Diagnostic and operative therapy options]. / Fingermittelgelenkfrakturen : Diagnostik und operative Therapiemöglichkeiten.

Joint fractures of the fingers often entail operative interventions in contrast to extra-articular fractures. These types of fracture are inclined to dislocate in addition to the actual fracture. The proximal interphalangeal (PIP) joint in particular often shows comminuted fractures due to the long leverage of the finger and a relatively small diameter of the joint. The clinical examination, X-ray diagnostics and if necessary computed tomography allow the classification into stable and unstable fractures. Unstable fractures must be treated by surgical reduction and fixation. A multitude of operative techniques are available for these mostly complicated fractures. The foremost goal is a stable osteosynthesis of the fracture with repositioning of the dislocation, which enables early physiotherapy in order to prevent tendon adhesion and contracture. This article presents the different types of PIP joint fractures, their specific surgical treatment and postoperative treatment regimens.

[Carpus and distal radioulnar joint : Clinical and radiological examination]. / Carpus und distales Radioulnargelenk : Klinische und röntgenologische Untersuchung.

A precise medical history and specific symptom-oriented clinical tests of the wrist joint should always precede any radiological, computed tomography (CT) or magnetic resonance imaging (MRI) diagnostics. In many cases, specific clinical tests of the wrist joint allow at least a preliminary diagnosis, which can be supported by standard radiography using correct projections. A systematic approach is recommended covering the radiocarpal, midcarpal, ulnocarpal and distal radioulnar joints. Exact identification of the palpable anatomic landmarks is mandatory for correct application and interpretation of the various clinical tests. The results of the clinical tests in combination with radiological imaging can often detect precisely ruptures of distinct wrist joint ligaments and localized arthritis.

[Joint infections of the hand]. / Gelenkinfektionen der Hand.

Joint infections of the hand may lead to irreversible lesions and impairment of hand function due to early cartilage damage. Furthermore, persistent infections which are not treated immediately can cause osteitis and/or spread systemically. Finger joints are prone to infection due to bite wounds or crush and sharp injuries. Whereas the wrist is often affected in patients with immunosuppression or chronic diseases, such as diabetes mellitus. If diagnosis and therapy are delayed, joint damage may be inevitable. Therefore, urgent treatment of the infected joint is imperative to preserve the function of the hand. This article reviews the current diagnostics and treatment of joint infections of the hand.

[Flexor tendon transplantation]. / Beugesehnentransplantation.

BACKGROUND: Insufficiency of both flexor tendons of a finger considerably disrupts the function of the whole hand. Flexor tendon transplantation represents the best way to reconstruct or improv function in many cases. OBJECTIVES: Based on the literature and our own results, not only the current state of the surgical technique, but also the opportunities and dangers of this sophisticated operation, are represented. Knowledge of alternative methods is important. METHODS: With a follow-up of between 2 to 12 years, a total of 272 patients who underwent flexor tendon transplantation in the hand during several periods from 1974 to 2000 were investigated. RESULTS: Similar to the international literature, our long-term results did not specify the exact surgical technique (pedicled or free). According to the Buck-Gramcko score, 32 % had very good results, 26.4 % good, 15.1 % satisfactory, and 26.5 % poor. CONCLUSIONS: Numerous details need to be considered before, during, and after surgery. For the patient, the procedure has tremendous significance in many ways; thus, this operation should only be performed by an experienced hand surgeon.

[Suture techniques for flexor tendons of the hand]. / Nahttechniken für Beugesehnen der Hand.

BACKGROUND: The success of the flexor tendon suture depends on many factors. An important factor is that the tendon suture technique that must be carried out for flexor tendons is considerably more complex and more precise than for all other tendons of the body. OBJECTIVES: To discover important technical points that need to be considered during flexor tendon suturing. METHOD: We compiled the most important technical details in flexor tendon suturing from the literature and from personal experience. RESULTS: Details on core suture, peripheral suture, the tensile strength, gapping, the circulation of sutured tendons, gliding resistance and excisions are discussed. CONCLUSIONS: Flexor tendon suturing must be performed taking great care to conserve tissue.