Development of an In Vitro Swan Neck Deformity Biomechanical Model.

BACKGROUND: Injury to the finger's extensor mechanism is a common cause of swan neck deformity (SND). Progression of extensor and flexor tendon imbalance negatively affects laxity of the volar plate, resulting in the inhibition of proper finger motion. The complexity of finger anatomy, however, makes understanding the pathomechanics of these deformities challenging. Therefore, development of an SND model is imperative to understand its influence on finger biomechanics and to provide an in vitro model to evaluate the various treatment options. METHODS: The index, middle, and ring fingers from 8 cadaveric specimens were used in an in vitro active motion simulator to replicate finger flexion/extension. An SND model was developed through sectioning of the terminal extensor tendon at the distal insertion (creating a mallet finger) and transverse retinacular ligament (TRL). A strain gauge inserted under the volar plate measured laxity of the plate, and electromagnetic trackers recorded proximal interphalangeal joint (PIPJ) angles. RESULTS: Strain in the volar plate increased progressively with creation of the mallet and SND conditions (P = .015). Although not statistically significant, the mallet finger condition accounted for 26% of the increase, whereas sectioning of the TRL accounted for 74% (P = .031). As predicted, PIPJ hyperextension was not detectable by joint angle measurement; however, the PIPJ angle had a strong positive correlation with volar plate strain (R2 = 1.0, P < .001). CONCLUSION: Volar plate strain measurement, in an in vitro model, can detect an induced SND. Moreover, as a surrogate for PIPJ hyperextension, volar plate strain may be useful to evaluate the time-zero effectiveness of various surgical interventions.

The Use of Dynamic Assist Orthosis for Muscle Reeducation following Brachial Plexus Injury and Reconstruction.

Therapeutic management of brachial plexus injuries remains complex. The impact of brachial plexus injuries on everyday human functioning should not be underestimated. Early active-assisted range of motion following such injuries may prevent myostatic contractures, minimize muscle atrophy, facilitate muscle fiber recruitment, and enable a faster return to baseline strength levels. The dynamic assist elbow flexion orthosis proposed is designed to provide patients with a graded system for muscle reeducation and function. No clinical data are currently available on the use of this orthosis design; however, this article presents a treatment option based on sound clinical reasoning to facilitate rehabilitation following this devastating injury.

The Effect of Simulated Total Distal Interphalangeal Joint Stiffness on Grip Strength.

PURPOSE: Production of a functional grip pattern requires the concerted action of numerous structures within the hand. This study quantifies the effect of total distal interphalangeal joint (DIPJ) stiffness to grip strength. METHODS: Fifty (25 men, 25 women, 100 hands) individuals with a mean age of 38 years (range: 17-69 years) were recruited. Exclusion criteria included history of previous upper limb injury, neuropathies, or systemic disease. Custom thermoplastic orthoses were used to splint participants' DIPJ in full extension simulating stiffness. Grip strength before and after splinting was measured using a calibrated Jamar dynamometer. Data were analyzed using paired and independent sample t tests and 2 × 2 repeated-measures analysis of variance with hand dominance and configuration (splinted or unsplinted) as within-subject factors. RESULTS: Restriction of DIPJ flexion led to a 20% decrease in grip strength (P < .001). There was no significant difference in this decrease between dominant and non-dominant hands. Univariate analysis did not demonstrate any interaction between hand dominance and testing configuration. Post hoc analysis revealed no statistical difference in baseline grip strength between the dominant and non-dominant hands. Furthermore, men had significantly stronger grip strength than women in all configurations (P < .001). CONCLUSIONS: Flexion at the DIPJ contributes significantly to grip strength, and stiffness at this joint greatly limits functional capabilities of the hand. This necessitates the need for targeted rehabilitation in DIPJ injuries to minimize adverse effects on grip strength.

OBJECTIF: Pour produire un schéma de préhension fonctionnel, il faut l'action concertée de multiples structures de la main. La présente étude quantifie l'effet de la raideur de toute l'articulation interphalangienne distale (AIPD) sur la force de préhension. MÉTHODOLOGIE: Les chercheurs ont recruté 50 personnes (25 hommes, 25 femmes, 100 mains) d'un âge moyen de 38,28 ans (plage de 17 à 69 ans). Les critères d'exclusion incluaient des antécédents de blessure d'un membre supérieur, de neuropathie ou de maladie systémique. Les chercheurs ont utilisé des orthèses thermoplastiques sur mesure pour mettre une attelle sur l'AIPD en pleine extension des participants, afin de simuler la raideur. Ils ont mesuré la force de préhension avant et après la pose de l'attelle à l'aide d'un dynanomètre Jamar calibré. Ils ont évalué les données à l'aide de tests de Student appariés et indépendants et de l'analyse de variance à mesures répétées 2×2 et se sont servis de la dominance de la main et de la configuration (avec ou sans attelle) comme facteurs individuels. RÉSULTATS: La restriction de la flexion de l'AIPD suscitait une diminution de la force de préhension de 20 % (P < 0,001). Il n'y avait pas de différence significative entre les mains dominantes et non dominantes. L'analyse univariée n'a pas démontré d'interaction entre la dominance de la main et la configuration des tests. L'analyse a posteriori n'a révélé aucune différence statistique de la force de préhension entre les mains dominantes et non dominantes en début d'étude. De plus, les hommes avaient une beaucoup plus grande force de préhension que les femmes dans toutes les configurations (P < 0,001). CONCLUSIONS: La flexion de l'AIPD contribue de manière significative à la force de préhension, et la raideur de l'articulation limite considérablement la capacité fonctionnelle de la main. Ainsi, il faut prévoir une réadaptation ciblée des lésions de l'AIPD pour en réduire le plus possible les effets indésirables sur la force de préhension.

The Effect of Isolated Finger Stiffness on Adjacent Digit Function.

BACKGROUND: Isolated stiffness in a single finger can affect the function of adjacent digits and decrease overall hand function due to the quadriga phenomenon. This study objectively quantifies the dysfunctional impact of each individual stiff finger upon the remaining digits. METHODS: Twenty-five individuals (10 men and 15 women) with a mean age of 31 years (range, 18-58 years) without any upper limb pathology, neuropathy, or systemic illness were recruited. Volar-based finger splints were used to hold individual digits of the dominant hand (24 right and 1 left) sequentially in full extension at the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints. Motion of the remaining 3 nonsplinted digits was assessed using a finger goniometer and linear scale to measure the total active range of motion (TAM) and fingertip-to-distal palmar crease (DPC) distance. TAM before and after splinting for each digit was compared using 1-way analysis of variance (ANOVA). RESULTS: Splinting of any individual finger resulted in a significant reduction in the TAM of all adjacent fingers, regardless of which finger was splinted ( P < .001). Digits immediately adjacent to the splinted finger were more heavily impacted compared with nonadjacent digits. Splinting of the ring finger produced the greatest detriment, with a 26% to 47% reduction in the TAM and a DPC distance greater than 40 mm in a third of participants. The index finger caused the least disturbance to remaining digital motion. CONCLUSIONS: Isolated finger stiffness causes a variable degree of dysfunction on adjacent normal digits. This emphasizes the need for a focused and proactive approach to restore full active motion following isolated finger injuries to prevent persistent functional sequelae of the hand.

Pathomechanics and Management of Secondary Complications Associated with Tendon Adhesions Following Flexor Tendon Repair in Zone II.

Despite the number of rehabilitation strategies and guidelines developed to maximize the gliding amplitude of repaired tendons, secondary complications, such as decreased range of motion and stiffness associated with tendon adhesions, commonly arise. If left untreated, these early complications may lead to secondary pathomechanical changes resulting in fixed deformities and decreased function. Therefore, an appropriate treatment regimen must not only include strategies to maintain the integrity of the repaired tendon, but must also avoid secondary complications due to reduced gliding amplitude. This review presents a biomechanical analysis of the dynamics of tendon gliding following repair in zone II and rehabilitation strategies to minimize secondary complications related with tendon adhesions.

Zone III flexor tendon injuries - A proposed modification to rehabilitation.

In this manuscript, these authors have utilized years of clinical experience to suggest rehabilitation modifications for Zone III flexor tendon injuries. - VictoriaPriganc, PhD, OTR, CHT, CLT, Practice Forum Editor.

Relationship Between Juncturae Tendinum and Sagittal Bands.

The juncturae tendinum and sagittal bands transmit precise forces through the dorsum of the hand. Both structures are integral in the mechanics of normal digital extension and in stabilization of the metacarpophalangeal (MCP) joints. Extensor tendon injury, or rupture/attenuation of sagittal bands and/or juncturae tendinum, may disrupt the kinematic chain and lead to a number of abnormal hand postures and motions. Early treatment of extensor tendon and/or sagittal band injury is dependent upon proper recognition of primary pathology. Proper evaluation and the use of special clinical tests should be implemented to rule out other pathologies. Once diagnosed, treatment may consist of relative motion splinting and standard pain/edema control measures to increase joint motion, tendon excursion, and functional use of the hand.

Static progressive orthosis for patients with limited radial and/or ulnar deviation: an innovative orthotic design.

After injury to the wrist and forearm, therapists and patients frequently work to regain the motions of wrist flexion/extension and forearm pronation/supination. Although these motions play a vital role in everyday functioning, for some, limitations in wrist radial/ulnar deviation can also present functional challenges. These authors describe the creation and utilization of a static progressive orthosis to assist a patient in regaining wrist radioulnar deviation

Rehabilitation considerations in the management of terrible triad injury to the elbow.

An elbow dislocation associated with a radial head and coronoid fractures is termed a terrible triad. This injury almost always renders the elbow unstable requiring surgical intervention. The primary goal of surgery is to stabilize the elbow to permit early motion to prevent stiffness. Recent literature has improved our understanding of elbow anatomy and biomechanics as well as the pathoanatomy of this injury. This article reviews key concepts that will allow the surgeon and therapist to apply an systematic rehabilitation approach when managing such injuries.

Controlled active mobilization after dorsal capsulodesis to correct capitolunate dissociation.

STUDY DESIGN: Case Report. Capitolunate instability is a form of midcarpal instability. If conservative management is unsuccessful, surgical reconstruction is often indicated. However, the literature is limited regarding postoperative management after reconstruction. Often patients are immobilized for a 6- to 12-week period, which can produce secondary complications, including wrist stiffness, tendon adherence, and muscle atrophy. The purpose of the case report was to demonstrate that controlled early mobilization may be implemented postoperatively after dorsal capsulodesis procedures to correct capitolunate instability. This early mobilization may prevent secondary complications, which can be associated with lengthy immobilization periods. A 27-year-old female underwent a dorsal capsulodesis procedure to correct capitolunate instability. The intraoperative findings of the reconstruction and tension on the capsulodesis procedure were communicated to the therapist by the surgeon. This close communication allowed the therapist to institute early controlled mobilization immediately postoperatively using a hinged wrist splint. The patient was followed by our unit for 13 years. Early controlled mobilization using a hinged wrist splint may have maximized the subject's recovery, with no secondary complications. At 13-year follow-up, fluoroscopic and radiographic examination was normal, and no symptoms of pain or instability had reoccurred. In conclusion, early controlled mobilization using a hinged wrist splint may optimize the recovery period while retaining the desired arc of motion that is set intraoperatively. LEVEL OF EVIDENCE: 4.

Swan neck deformity after distal interphalangeal joint flexion contractures: a biomechanical analysis.

The relationship between the flexor and extensor systems of the digits is both intricate and balanced, such that disruption of one system can affect the entire dynamics of the finger. The imbalance may be obvious, whereas the precipitating factor may be less obvious. These authors describe a case and provide a detailed biomechanical analysis of how a flexion contracture of the distal interphalangeal joint led to a swan neck deformity in one of their patients.

Postoperative management of extensor pollicis longus repairs within close vicinity to or within the extensor retinaculum.

Therapists are continually modifying tendon protocols as part of the quest to create the perfect balance between tendon protection and tendon glide. Although much literature exists on the rehabilitation of the long flexor and extensor tendons to the digits, little literature exists on the rehabilitation of the extensor pollicis longus (EPL) tendon. This author used concepts related to tendon glide, tendon tethering, and early active mobilization to create a new splint and subsequent protocol for patients after an EPL laceration near the extensor retinaculum.

Postoperative management of carpometacarpal joint fracture dislocation of the hand: A case report.

Injury to the carpometacarpal joints is rare. The strong ligamentous attachments and carpal bone alignment readily resist displacement. To the authors' knowledge, there are no studies evaluating postoperative recovery regimens of carpometacarpal fracture dislocations. The present study describes a postoperative hand therapy regimen that used a novel carpometacarpal brace permitting early mobilization.

Contribution of the ulnar digits to grip strength.

PURPOSE: To determine the contribution of ulnar digits to overall grip strength. SUBJECTS: Fifty individuals (25 men and 25 women; 100 hands) with a mean age of 35.6 years (range 19 to 62 years) were tested. Exclusion criteria included previous history of hand injuries, entrapment neuropathies and systemic diseases. METHODS: Ethics approval was granted before testing. A calibrated Jamar dynamometer (Lafayette Instrument Company, USA) was used to test subjects in three configurations: entire hand - index, middle, ring and little fingers; index, middle and ring fingers; and index and middle fingers. Little and ring fingers were excluded using generic hand-based finger splints. The order of testing was kept constant, and subjects were tested three times on each hand for each configuration. The average of the three trials at each configuration was recorded. Subjects received 1 min of rest between each testing configuration. The data were analyzed using a 3×2 repeated measures ANOVA with hand dominance and configuration as the within-subject factors, followed by two independent sample t tests to compare flexor digitorum superficialis (FDS) independence and FDS nonindependence on right and left hand grip strength measurements in the index, middle, ring and little condition. RESULTS: Univariate results demonstrated that grip strength was significantly predicted by the interaction between hand dominance and configuration, while the parsing of the interaction term demonstrated greater grip strength across all levels of configuration for the dominant and nondominant hand. There were no significant differences between FDS independence and FDS nonindependence for either hand on grip strength. DISCUSSION: The results indicate a significant decrease in grip strength as ulnar fingers were excluded. Furthermore, exclusion of the little finger has differing effects on the grip strength of the dominant and nondominant hands - the dominant hand had a greater loss of strength with the little finger excluded than the nondominant hand. CONCLUSIONS: The ulnar two digits play a significant role in overall grip strength of the entire hand. In the present study, exclusion of the ulnar two digits resulted in a 34% to 67% decrease in grip strength, with a mean decrease of 55%. Exclusion of the little finger from a functional grip pattern decreased the overall grip strength by 33%. Exclusion of the ring finger from a functional grip pattern decreased the overall grip strength by 21%. It is clear that limitation of one or both of the ulnar digits adversely affects the strength of the hand. In addition, there was no significant difference between grip strength of FDS-independent and FDS-nonindependent subjects for either hand.

Complications of extensor tendon repairs at the extensor retinaculum.

Literature describing surgical, post-operative management and outcomes following EDC repairs in close proximity to or within the extensor retinaculum is limited. This complex injury can result in decreased wrist and digital motion as well as loss of independent motion of the digits. This paper reviews complications following such injuries observed clinically as well as experimental simulation performed on cadaveric specimens. Our observations have direct implications to hand therapy practice and outcomes used following such injuries.

Static progressive versus three-point elbow extension splinting: a mathematical analysis.

Elbow joint contractures are often treated by using static progressive, dynamic, turnbuckle, or serial static splinting. These splint designs are effective in regaining functional elbow range of motion due to the high forces applied to the contracted tissues; however, regaining terminal elbow extension remains a challenge. Static progressive splints are commonly used to initiate treatment, however, are considered less effective in regaining terminal extension. Recently, the concept of converting a static progressive splint into a three-point static progressive splint (TPSPS) to regain terminal extension has been introduced. This paper mathematically analyzes the compressive and rotational forces in static progressive and TPSPSs. Our hypothesis was that three-point static progressive splinting was superior to the standard static progressive elbow extension splint in applying rotational forces to the elbow at terminal extension.

Dynamic splinting for the repair of the first extensor compartment tendons.

As a hand therapist, we don't really treat a lacerated tendon. The physician is the one that handles the repair. We actually are treating all the secondary problems that occur as a result of the injury and the repair. To quote Ken Flowers (JHT past editor), " Scar Wars" can end up being one of our biggest challenges. This author has demonstrated how adhesions can affect motion after a repair of tendons in the first extensor compartment. He has also designed a splint to help with "battling" this dilemma.-Peggy Fillion, OTR, CHT, Practice Forum Editor.