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Traumatic dislocations of the fourth and fifth metacarpals, in conjunction with dorsal hamate fractures, are a common entity that can lead to the instability of the fourth and fifth carpometacarpal (CMC) joints. The fracture of the hamate, usually in a coronal dorsal shear configuration, can lead to the dorsal subluxation of the hamatometacarpal joint. Open reduction and internal fixation of the hamate bone with a dorsally applied buttress plate can re-establish a stable and congruent joint surface and anatomically align the articular surfaces of the small and ring finger CMC joints. We present a technique of internal fixation of the hamate to facilitate the reduction of the hamatometacarpal joints. Using a dorsal approach centered over the fourth and fifth CMC joints, the joint surfaces are directly visualized and subsequent fixation of the hamate is performed using a 1.3-mm T-plate to securely buttress its articular surface. This technique presents an approach to the multifaceted injury pattern of fourth and fifth CMC dislocations associated with a hamate fracture.
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Introduction Wound dehiscence is the most common complication after spinal fusion procedures, resulting in an increase in mortality rate and hospital length of stay. Reconstruction of these wounds presents a challenge, as the spine is dependent on these implants for stability and must be maintained throughout the wound dehiscence treatment protocol. We describe a method for extending the thoracodorsal pedicle with an arteriovenous loop to permit an increased excursion of the latissimus dorsi muscle in patients with exposed implants and present the results of this procedure. Materials and Methods A retrospective review of patients treated with a latissimus free flap with saphenous vein pedicle extension for posterior spinal wounds from 2010 to 2020 were reviewed. Patient charts were reviewed for demographic information including comorbidities, previous spine operations, wound size and location, and postoperative complications including total flap loss, flap dehiscence, and need for secondary surgery. Results Six patients were identified who underwent a total of eight extended pedicle free flaps. Mean age was 64.8 years with a mean follow-up of 12.3 months (range, 6-20 months). Four wounds were in the cervicothoracic region with two wounds in the cervical region. Mean number of previous spine surgeries was 3.5 (range, 2-4). Mean wound size was 189 cm 2 with a mean vein graft length of 28 cm. Wound coverage was successful in five of six patients. Major complications occurred in five of six patients. Total flap loss occurred in two patients (33%) and both underwent a second extended latissimus flap from the contralateral side. Three patients developed postoperative flap dehiscence which resolved with regular dressing changes. Conclusion Extended pedicle latissimus flaps are an effective treatment for posterior spine wounds but are associated with a high complication rate, secondary to medically complex patients with multiple prior surgeries. Careful patient selection is critical for success.
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PURPOSE: Distal radioulnar joint (DRUJ) instability may occur after an injury, resulting in pain and reduced strength. When primary repair is not possible or initial fixation has failed, chronic instability may result, requiring a reconstructive procedure such as the Adams procedure. The first purpose of this study was to evaluate the role of the triangular fibrocartilage complex and various components of the interosseous membrane as they were sectioned. The second purpose was to evaluate the Adams procedure in stabilizing the forearm. METHODS: Eight fresh cadaver forearms were dynamically moved through an average range of 56.8° pronation to 54.8° supination and tested first with the forearm intact and then after sectioning each of the following structures: the dorsal (DRUL) and palmar radioulnar ligaments (PRUL), the distal interosseous membrane, and the central band. Finally, they were tested after reconstruction using the Adams procedure. During each forearm motion and provocative shuck, the motion of the radius and ulna were measured and the locations of the radial attachments of the DRUL, PRUL, and sigmoid notch and ulnar fovea were computed. RESULTS: Significant increases in the gap between the ulnar fovea and the attachment sites of the DRUL and PRUL were observed with incremental sectioning, most notably after sectioning of the central band. Reconstruction significantly reduced the gap at the DRUL and PRUL sites during dynamic motion. CONCLUSIONS: This study reinforces the concept that DRUJ stability depends on more than the radioulnar ligaments, ulnocarpal ligaments, and triangular fibrocartilage complex, but is also significantly affected by the distal and central interosseous membrane. Reconstruction reduces gapping. CLINICAL RELEVANCE: These results suggest that the Adams reconstruction is a reasonable option to address DRUJ instability but may be an incomplete solution in the setting of a ruptured interosseous ligament.
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Inestabilidad de la Articulación , Fenómenos Biomecánicos , Cadáver , Humanos , Inestabilidad de la Articulación/cirugía , Pronación , Radio (Anatomía) , Supinación , Cúbito , Articulación de la Muñeca/cirugíaRESUMEN
BACKGROUND: Scapholunate interosseous ligament (SLIL) injury following a fall on an outstretched hand may lead to carpal instability and in some cases require long-term rehabilitation following repair. Rehabilitation, especially in athletes, may include pushups, but little is known as to what type of pushup may be safer. OBJECTIVE: To determine biomechanical differences between two pushup positions (neutral or extended). METHODS: Six fresh cadaver wrists with pre-existing SLIL damage were uni-axially loaded in neutral and extension in order to simulate two different pushup styles. The motions of the scaphoid and lunate in relation to the radius were measured. The dorsal, proximal, and volar insertion sites of the SLIL were identified and, using the collected kinematic data, gap distances were calculated for each site. RESULTS: Gap distance between the proximal SLIL insertion points was significantly greater in neutral than in extension. There was a trend that the dorsal and volar SLIL insertion points were also greater in neutral than in extension. After the wrist was extended 90o, the scaphoid extended 70.1o and the lunate extended 28.6o compared to their positions with the wrist in neutral. CONCLUSION: The larger gap distances between the scaphoid and lunate in neutral suggest that a neutral style pushup could put higher forces on a wrist with pre-existing SLIL damage and may thus hinder recovery for a person with a repaired SLIL. A pushup in extension, in these injured wrists, may be less detrimental.
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Articulaciones del Carpo/fisiopatología , Ejercicio Físico/fisiología , Ligamentos/lesiones , Hueso Semilunar , Hueso Escafoides , Soporte de Peso/fisiología , Traumatismos de la Muñeca/fisiopatología , Anciano de 80 o más Años , Fenómenos Biomecánicos , Cadáver , Femenino , Humanos , Ligamentos/fisiopatología , MasculinoRESUMEN
High-energy open fractures of the tibia are frequently associated with tissue loss, wound contamination, and compromised vascularity that often result in amputation. The management of these severe injuries remains a challenge for orthopedic reconstructive surgeons. Studies have compared the timing of soft tissue coverage of Gustilo type IIIB open tibia fractures with associated outcomes such as rate of deep infection, primary union, length of hospitalization, flap failure, and eventual secondary amputation. These studies often highlight better outcomes with specific time domains that are not always attainable at a large tertiary hospital with multi-system trauma patients. Many studies do not account for delayed patient transfers after initial open fracture management elsewhere. This retrospective analysis of the limb salvage outcomes included 140 consecutive patients with Gustilo type IIIB open tibia fractures who presented to the authors' level I trauma center between 2001 and 2014. The authors included patients who required delayed coverage or who were transferred from outside institutions. The majority (77%) were male, and the mean age was 39.4 years. Motor vehicle accidents were the most common cause of injury, and 83% of patients obtained full weight-bearing status with successful limb salvage. Twenty patients had a secondary amputation, with the cause being refractory osteomyelitis in 52%. This study provides guidance on treating a heterogeneous patient population with severe open tibia fractures typically seen in a large tertiary hospital orthopedic trauma service. [Orthopedics. 2019; 42(5):260-266.].
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Fracturas Abiertas/cirugía , Recuperación del Miembro/métodos , Fracturas de la Tibia/cirugía , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Amputación Quirúrgica , Niño , Femenino , Fracturas Abiertas/complicaciones , Supervivencia de Injerto , Humanos , Masculino , Persona de Mediana Edad , Músculo Esquelético/trasplante , Osteomielitis/etiología , Osteomielitis/cirugía , Complicaciones Posoperatorias/etiología , Complicaciones Posoperatorias/cirugía , Procedimientos de Cirugía Plástica , Reoperación , Estudios Retrospectivos , Colgajos Quirúrgicos , Fracturas de la Tibia/complicaciones , Factores de Tiempo , Resultado del Tratamiento , Adulto JovenRESUMEN
PURPOSE: To determine the force required to maintain reduction of Geissler grade 4 scapholunate dissociations during physiological wrist motions. METHODS: Fresh-frozen cadaveric wrists with Geissler grade 4 scapholunate dissociations were identified by arthroscopy. Following reduction, a load cell was attached to measure the force across the scapholunate joint at a neutral position and during 4 different wrist motions re-created using a servohydraulic wrist simulator, including a large flexion-extension motion (FEM), small and large dart-thrower's motions (DTMs), and a large DTM with ulnar offset. RESULTS: Five wrists with isolated preexisting scapholunate interosseous ligament (SLIL) tears were analyzed. The force required to maintain reduction was significantly greater in extension than in flexion during the large FEM and large DTM with ulnar offset. The forces were significantly larger in this study of preexisting SLIL dissociations compared with results from a prior study of acutely sectioned SLILs. In addition, forces to maintain reduction during DTMs were significantly less than forces during FEMs. Finally, a set of 3 wrists with preexisting scapholunate and lunotriquetral interosseous ligament (LTIL) tears were identified and had significantly decreased forces to maintain reduction at maximum extension and had decreased maximal forces during a cycle of motion compared with the wrists with isolated SLIL tears. CONCLUSIONS: The forces required to maintain reduction of a Geissler grade 4 wrist are higher than forces after acutely sectioned SLIL. The forces are greater in extension than in flexion and less during the DTM compared with the FEM. Wrists with both SLIL and LTIL tears required less force to maintain reduction than those with isolated SLIL tears. CLINICAL RELEVANCE: This study helps determine the strength of reconstruction required to maintain reduction of a Geissler grade 4 scapholunate dissociation.
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Articulaciones del Carpo/fisiopatología , Inestabilidad de la Articulación/fisiopatología , Inestabilidad de la Articulación/terapia , Ligamentos Articulares/lesiones , Hueso Semilunar/fisiopatología , Hueso Escafoides/fisiopatología , Anciano , Artroscopía , Fenómenos Biomecánicos/fisiología , Cadáver , Femenino , Humanos , Inestabilidad de la Articulación/clasificación , Ligamentos Articulares/fisiopatología , Masculino , Movimiento/fisiología , Transductores , Articulación de la Muñeca/fisiologíaRESUMEN
PURPOSE: To determine the 6 degrees of freedom forces and moments in the distal radius that occur during a pushup or other active wrist motions. METHODS: Eight fresh-frozen cadaveric wrists were moved through 6 physiological motions and held at 1 static pushup position while the force through the distal radius was measured with a 6 degrees of freedom load cell. Three levels of compressive force were applied at the pushup position. RESULTS: Active wrist motions caused axial forces up to 283 N and moments up to 0.7 N-m. Those motions with a smaller range had significantly smaller axial forces than the larger flexion-extension or dart-thrower's motions. With an 89-N pushup force applied, the average maximum axial force was 69 N, the radially directed force was 12 N, and the moment about the radioulnar axis was 2.3 N-m. Linear extrapolation of the forces to 100% body weight indicate that the axial force going through the distal radius would be 663 N, the radial force would be 147 N, and the moment about the radioulnar axis would be 18.6 N-m. CONCLUSIONS: Large distal radius forces and moments can occur during pushup and active wrist motions. There are not only large axial compressive forces but also nontrivial radially directed forces. CLINICAL RELEVANCE: This study may help surgeons and therapists better treat complicated distal radius fractures as well as provide for better comparisons of existing or new distal radius plates and constructs that are designed to treat these complicated loading patterns.
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Ejercicio Físico/fisiología , Movimiento/fisiología , Radio (Anatomía)/fisiología , Articulación de la Muñeca/fisiología , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos/fisiología , Cadáver , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
PURPOSE: To determine the contact pressures between the scaphoid and lunate and the distal radius during 2 wrist push-up positions before and following scapholunate interosseous ligament (SLIL) sectioning. METHODS: Eight fresh cadaveric wrists were tested in a neutral flexion-extension (knuckle) push-up position and in an extended push-up position. Pressure measurements were acquired as each wrist was loaded with the wrist in extension and with the wrist in a neutral position. Data were acquired with the SLIL intact and following sectioning of its dorsal, volar, and proximal components. The wrist was disarticulated and a map drawn on each sensor to identify each joint fossa. RESULTS: A push-up performed with the wrist in extension caused a significantly greater peak pressure in the radioscaphoid fossa but not in the radiolunate fossa. Moving the wrist into extension caused a significant dorsal movement of the pressure centroid an average of 2.9 mm in the radiolunate fossa and an average of 5.7 mm in the radioscaphoid fossa. Sectioning the SLIL caused the centroid of pressure in the radioscaphoid fossa to significantly move an average 1.4 mm radially. CONCLUSIONS: A push-up with the wrist in extension causes a significant increase in the pressure in the radioscaphoid fossa but not in the radiolunate. This finding may help explain why degenerative arthritis first develops in the radioscaphoid fossa before involving the radiolunate fossa. As expected, gapping that occurs with SLIL injury was observed here as a radial translation of the scaphoid and not as a movement of the lunate. The new location of scaphoid contact may be an additional reason for the development of radioscaphoid arthritis occurring before radiolunate arthritis. CLINICAL RELEVANCE: This study provides a possible explanation as to why degenerative arthritis may first occur in the radioscaphoid fossa.
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Ligamentos Articulares/lesiones , Movimiento/fisiología , Presión , Articulación de la Muñeca/fisiología , Anciano , Cadáver , Femenino , Humanos , Hueso Semilunar/fisiología , Masculino , Hueso Escafoides/fisiologíaRESUMEN
PURPOSE: To create a biomechanical model of palmar midcarpal instability by selective ligament sectioning and to analyze treatment by simulated partial wrist arthrodesis. METHODS: Nine fresh-frozen cadaver arms were moved through 3 servohydraulic actuated motions and 2 passive wrist mobilizations. The dorsal radiocarpal, triquetrohamate, scaphocapitate, and scaphotrapeziotrapezoid ligaments were sectioned to replicate palmar midcarpal instability. Kinematic data for the scaphoid, lunate, and triquetrum were recorded before and after ligament sectioning and again after simulated triquetrohamate arthrodesis (TqHA) and radiolunate arthrodesis (RLA). RESULTS: Following ligament sectioning, the model we created for palmar midcarpal instability was characterized by significant increases in (1) lunate angular velocity, (2) lunate flexion-extension, and (3) dorsal/volar motion of the capitate during dorsal/volar mobilizations. Simulated TqHA caused significantly more scaphoid flexion and less extension during the wrist radioulnar deviation motion. It also increased the amount of lunate and triquetral extension during wrist flexion-extension. Simulated RLA significantly reduced scaphoid flexion during both wrist radioulnar deviation and flexion-extension. CONCLUSIONS: Both simulated arthrodeses eliminate wrist clunking and may be of value in treating palmar midcarpal instability. However, simulated RLA reduces proximal row motion whereas simulated TqHA alters how the proximal row moves. Long-term clinical studies are needed to determine if these changes are detrimental. CLINICAL RELEVANCE: Palmar midcarpal instability is poorly understood, with most treatments based on pathomechanical assumptions. This study provides information that clinicians can use to design better treatment strategies for this unsolved condition.
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Artrodesis , Fenómenos Biomecánicos/fisiología , Articulaciones del Carpo/cirugía , Inestabilidad de la Articulación/cirugía , Articulación de la Muñeca/cirugía , Anciano , Anciano de 80 o más Años , Cadáver , Articulaciones del Carpo/fisiopatología , Femenino , Hueso Ganchoso/fisiopatología , Hueso Ganchoso/cirugía , Humanos , Inestabilidad de la Articulación/fisiopatología , Ligamentos Articulares/lesiones , Masculino , Persona de Mediana Edad , Hueso Piramidal/fisiopatología , Hueso Piramidal/cirugía , Articulación de la Muñeca/fisiopatologíaRESUMEN
Background Damage to the interosseous membrane (IOM) can alter load transmission between the radius and ulna and decrease their axial stability. Less is known about the effect of IOM sectioning on the transverse stability between the radius and ulna. Purpose The purpose of this study was to quantify the radioulnar gapping at the distal radioulnar joint (DRUJ) during forearm rotation when the IOM was experimentally sectioned while maintaining the integrity of the distal radioulnar ligaments. Methods In 12 fresh-frozen cadaver forearms tested in a combined wrist-forearm simulator, the increase in gap between the radius and ulna, at the level of the DRUJ, was determined during cyclic forearm rotation following IOM sectioning. Results IOM sectioning caused a significant increase in dorsal gapping at the DRUJ by 2.1 mm in supination and 0.6 mm in pronation. It also caused an increase in palmar gapping by 1.3 mm in supination and 0.5 mm in pronation. Conclusion This experiment has shown that the IOM has an important role in stabilizing the DRUJ, especially in supination, and that IOM sectioning caused greater loads on the palmar and dorsal radioulnar ligaments. Since DRUJ instability is primarily treated by fixing the laxity at the dorsal radioulnar ligament (DRUL) and palmar radioulnar ligament (PRUL), untreated IOM damage could permit additional injury and instability to the radioulnar ligaments or their reconstruction. Clinical Relevance Reconstruction of a torn IOM should be considered in the presence of persistent DRUJ instability following DRUJ reconstruction.
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Background Proximal row carpectomy (PRC) is contraindicated in wrists with preexisting arthritis of the proximal capitate or radiolunate fossa. Patients with these conditions frequently pursue wrist arthrodesis with its associated functional limitations. Questions/Purposes The purpose of this study was to evaluate the results of using lateral meniscal allograft interposition (LMAI), in combination with PRC, in patients with symptomatic wrist arthritis. The primary question is whether this allograft will allow wrist function comparable to that in patients having only a PRC. A secondary question was to determine the short-term longevity of the allograft. Patients/Method Between 2006 and 2012, nine wrists underwent PRC with LMAI. Patient demographics and rates of complication or graft failure were determined. During independent clinical exams, functional outcomes were reviewed, patients completed a Disabilities of the Arm, Shoulder, and Hand (DASH) scores, and radiographs were taken. Results Four patients met the inclusion criteria, having clinical follow-up at an average of 4.2 years. DASH scores at the time of follow-up ranged from 9 to 33, with an average of 24. Average radiocapitate joint space in the first postoperative radiograph was 2.8 mm compared with 1.8 mm at the time of final follow-up. No wrists went on to arthrodesis. Conclusion Early outcomes of PRC with LMAI are comparable to those results found in the literature of PRC alone. LMAI with PRC may be a valid short-term option as a motion-preserving procedure in those patients contraindicated to having a PRC alone. Level of Evidence Level IV.
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PURPOSE: To determine the in vitro force between the scaphoid and the lunate supported by the scapholunate interosseous ligament (SLIL) during 2 wrist pushup positions. METHODS: Six fresh-frozen cadaveric wrists were tested in a neutral flexion-extension (knuckle) pushup position and in an extended pushup position. Tensile forces were measured across the scapholunate joint as half body weight axial forces were applied through the radius and ulna. Forces were measured after sectioning the SLIL, after also sectioning the dorsal radiocarpal and dorsal intercarpal ligaments, and then after also sectioning the radioscaphocapitate ligament. RESULTS: In the neutral position with the SLIL sectioned, the tensile force across the scapholunate joint was significantly larger in the extended position (45 N) than in the neutral position (25 N). Sectioning additional ligaments did not significantly increase the measured force. Extrapolation of the measured force in wrist extension with application of 1 time body weight suggests a force of 110 N would occur in the SLIL. CONCLUSIONS: This study demonstrated that, with the SLIL sectioned, with or without the dorsal radiocarpal, dorsal intercarpal, and radioscaphocapitate ligaments sectioned, the tensile force across the scapholunate joint is greater in extension than in the neutral wrist position. CLINICAL RELEVANCE: This study helps characterize the forces experienced across the scapholunate articulation when the SLIL is disrupted.
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Articulaciones del Carpo/fisiopatología , Ejercicio Físico/fisiología , Ligamentos Articulares/fisiopatología , Soporte de Peso/fisiología , Anciano , Anciano de 80 o más Años , Cadáver , Humanos , Hueso Semilunar , Rango del Movimiento Articular , Hueso Escafoides , Resistencia a la Tracción/fisiología , Articulación de la MuñecaRESUMEN
HYPOTHESIS: The purpose of our study was to determine the relative contributions of the annular ligament, proximal band, central band, and distal band of the interosseous membrane in preventing dislocation of the proximal radius. METHODS: In part 1 of the study, 8 forearms were loaded transversely with the forearm intact, and the central band, proximal band, and annular ligament were sequentially sectioned to determine the percentage contribution of each structure in preventing transverse radial displacement. In part 2, 12 forearms were cyclically supinated and pronated while optical sensors measured radial and ulnar motion. Transverse radial head motion was computed as the distal band, central band, and proximal band (and annular ligament) were sequentially sectioned. RESULTS: In part 1, there was no significant difference in the percentage contribution of each structure in preventing radial transverse displacement. In part 2, only after sectioning of the central band did significant radial head displacement occur. Greater displacements occurred in supination than in pronation. Dislocation of the proximal radius occurred in 2 arms after sectioning of all 3 structures. DISCUSSION: Under pure transverse displacement, the central band, annular ligament, and proximal band equally contributed to stabilizing the radius. However, during forearm rotation, the central band contributed more to radial head stability than the annular ligament and proximal band. Our study contributes to our knowledge of forearm biomechanics, demonstrating the importance of the central band in providing proximal radial head stability. Forceful supination should be avoided after surgical procedures designed to stabilize the radial head.
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Articulación del Codo/fisiopatología , Luxaciones Articulares/prevención & control , Ligamentos Articulares/fisiopatología , Procedimientos Ortopédicos/métodos , Radio (Anatomía)/cirugía , Anciano , Fenómenos Biomecánicos , Cadáver , Femenino , Humanos , Luxaciones Articulares/fisiopatología , Ligamentos Articulares/cirugía , Masculino , Lesiones de CodoRESUMEN
PURPOSE: To examine the force experienced by the scapholunate interosseous ligament (SLIL) during movements of the wrist. METHODS: Six fresh-frozen cadaveric wrists were freed of soft tissue and tested in a computer controlled, servohydraulic simulator. Each wrist was tested cyclically through simulated active arcs of flexion-extension and dart throw motion. Tensile forces were recorded across the scapholunate joint with the SLIL cut through a cable placed through the scaphoid to the lunate and fixed to a force transducer external to the wrist. RESULTS: The average recorded maximal tensile force across the scapholunate joint during all tested motions was 20 N. During wrist flexion-extension and the dart throw motion, SLIL force was greater at maximum extension than at maximum flexion. No significant differences among the different motions at maximum flexion or extension or for maximal force during motion were found. CONCLUSIONS: Forces during the flexion-extension and dart throw motions were significantly higher in extension than in flexion. However, during simple unresisted wrist motions, the force did not exceed 20 N. CLINICAL RELEVANCE: This information can be used to evaluate surgical methods used for SLIL repairs and thus provide better outcomes for patients.
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Articulaciones del Carpo/fisiología , Ligamentos Articulares/lesiones , Ligamentos Articulares/fisiopatología , Rango del Movimiento Articular/fisiología , Articulación de la Muñeca/fisiología , Cadáver , Humanos , Hueso Semilunar , Hueso Escafoides , Resistencia a la Tracción/fisiologíaRESUMEN
PURPOSE: To examine the anatomy and function of the forearm interosseous membrane by exploring the anatomical insertions of the central band (CB) on the radius and the ulna and by quantifying the length of the intact ligament and replacement grafts located at the original CB attachment sites and alternative locations. METHODS: Eight fresh cadaver forearms were supinated and pronated and the wrist was extended and flexed while the motion between the distal radius and ulna were recorded. The length of the CB was computed for the intact CB as well for several alternative graft orientations and positions. RESULTS: The maximum length of the CB did not significantly change among different wrist motions. However, with the wrist in a static neutral position, the CB length was significantly shorter in forearm supination than in neutral. During active forearm rotation when CB replacement grafts were positioned distal or proximal to the original CB site, yet still parallel to it, each had a similar trend to be longer in neutral than in supination. If a graft was more transversely oriented, the computed CB length would be 1.6 mm shorter in supination than in neutral. CONCLUSIONS: These results support tensioning a CB graft with the forearm in supination if the goal is to maximize graft tension and to maintain the native 22° angle for a CB graft between the radius and ulna. The results also suggest that the CB graft can probably be located slightly distal or slightly proximal to its original attachment sites. CLINICAL RELEVANCE: Reconstruction of the interosseous membrane has been hampered by a lack of understanding of its length changes with forearm or wrist motion. These results provide a starting point in helping clinicians understand how to more precisely reconstruct this ligament in an anatomical manner.
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Antebrazo/anatomía & histología , Antebrazo/fisiología , Membranas/anatomía & histología , Membranas/fisiología , Movimiento/fisiología , Anciano , Fenómenos Biomecánicos/fisiología , Cadáver , Femenino , Humanos , Masculino , RotaciónRESUMEN
PURPOSE: To better define normal wrist joint forces during wrist motion and forearm motion at specific wrist and forearm positions and to see if there is a relationship between these forces and the amount of ulnar variance. A secondary purpose was to determine the relationship between the thickness of the articular disk of the triangular fibrocartilage complex and the amount of force transmitted through the distal ulna. METHODS: Multi-axis load cells were attached to the distal radius and ulna of 9 fresh cadaver forearms. The axial radial and ulnar compressive forces were recorded while each wrist was moved through wrist and forearm motions using a modified wrist joint simulator. During each motion, the tendon forces required to cause each motion were recorded. The ulnar variance and triangular fibrocartilage complex articular disc thickness were measured. RESULTS: The axial force through the distal ulna and the wrist extensor forces were greatest with the forearm in pronation. No relationship was found between the amount of force through the distal ulna and the amount of ulnar variance. A strong inverse relationship was found between the triangular fibrocartilage complex thickness and the ulnar variance. CONCLUSIONS: Wrists with positive ulnar variance have generally been thought to transmit greater loads across the distal ulna, which has been felt to predispose these wrists to the development of ulnar impaction. The results of this study appear to show that all wrists have similar loading across the distal ulna regardless of ulnar variance. By comparison, pronation relatively increases loading across the distal ulna. CLINICAL RELEVANCE: Because these results suggest that within reasonable ranges of ulnar variance loading across the distal ulna is independent of ulnar variance, the clinically observed incidence of ulnar impaction is more likely the result of increased wear on a thinner and less durable triangular fibrocartilage complex than due to increased distal ulna loading in ulnar positive variant wrists.
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Fenómenos Biomecánicos/fisiología , Antebrazo/fisiología , Pronación/fisiología , Radio (Anatomía)/fisiología , Rango del Movimiento Articular/fisiología , Supinación/fisiología , Fibrocartílago Triangular/fisiología , Cúbito/fisiología , Soporte de Peso/fisiología , Articulación de la Muñeca/fisiología , Anciano , Femenino , Humanos , Masculino , Modelos Biológicos , Valores de ReferenciaRESUMEN
PURPOSE: To determine whether flexor carpi ulnaris (FCU) forces and tendon displacements change after pisotriquetral arthrodesis or after pisiform excision. METHODS: Nine cadaver wrists were moved through 4 variations of a dart throw motion, each having an oblique plane of motion, but with different ranges of motion and different antagonistic forces. The FCU tendon force and movement were measured in the intact wrist, following pisotriquetral arthrodesis, and following pisiform excision. Changes in force and tendon movement were compared using a repeated measures analysis of variance. RESULTS: After excision of the pisiform, a significantly greater FCU force was required during the 2 variations of the dart throw motion having a larger range of motion and during the smaller motion having a larger antagonistic force. Pisotriquetral arthrodesis did not cause a significant increase in the peak FCU force. Excision of the pisiform caused the FCU tendon to significantly retract during all wrist motions as compared to the intact wrist or after pisotriquetral arthrodesis. CONCLUSIONS: Greater FCU forces are required to move the wrist when the pisiform with its moment arm function has been removed. This occurs during large oblique plane wrist motions and also in a smaller motion when greater antagonistic forces are applied. Excision of the pisiform also allows the FCU to move proximally, again because its moment arm function has been eliminated. CLINICAL RELEVANCE: Excision of the pisiform requires greater FCU forces during large wrist motions and during motions that include large gripping forces such that excision may be a concern in high-demand patients with pisotriquetral arthritis. Although pisotriquetral arthrodesis does not alter the mechanical advantage of the FCU, its use in high-demand patients with pisotriquetral osteoarthritis cannot yet be recommended until the effects of that arthrodesis on midcarpal kinematics are further clarified.
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Movimiento/fisiología , Osteoartritis/fisiopatología , Osteoartritis/cirugía , Hueso Pisiforme/cirugía , Tendones/fisiología , Anciano , Artrodesis , Fenómenos Biomecánicos , Cadáver , Femenino , Humanos , MasculinoRESUMEN
PURPOSE: Controversy exists as to whether a proximal row carpectomy (PRC) is a better procedure than scaphoid excision with 4-corner arthrodesis for preserving motion in the painful posttraumatic arthritic wrist. The purpose of this study was to determine how the kinematics and tendon forces of the wrist are altered after PRC and 4-corner arthrodesis. METHODS: We tested 6 fresh cadaver forearms for the extremes of wrist motion and then used a wrist simulator to move them through 4 cyclic dynamic wrist motions, during which time we continuously recorded the tendon forces. We repeated the extremes of wrist motion measurements and the dynamic motions after scaphoid excision with 4-corner arthrodesis, and then again after PRC. We analyzed extremes of wrist motion and the peak tendon forces required for each dynamic motion using a repeated measures analysis of variance. RESULTS: Wrist extremes of motion significantly decreased after both the PRC and 4-corner arthrodesis compared with the intact wrist. Wrist flexion decreased on average 13° after 4-corner arthrodesis and 12° after PRC. Extension decreased 20° after 4-corner arthrodesis and 12° after PRC. Four-corner arthrodesis significantly decreased wrist ulnar deviation from the intact wrist. Four-corner arthrodesis allowed more radial deviation but less ulnar deviation than the PRC. The average peak tendon force was significantly greater after 4-corner arthrodesis than after PRC for the extensor carpi ulnaris during wrist flexion-extension, circumduction, and dart throw motions. The peak forces were significantly greater after 4-corner arthrodesis than in the intact wrist for the extensor carpi ulnaris during the dart throw motion and for the flexor carpi ulnaris during the circumduction motion. The peak extensor carpi radialis brevis force after PRC was significantly less than in the intact wrist. CONCLUSIONS: The measured wrist extremes of motion decreased after both 4-corner arthrodesis and PRC. Larger peak tendon forces were required to achieve identical wrist motions with the 4-corner arthrodesis compared with the intact wrist. We observed smaller forces for the PRC. CLINICAL RELEVANCE: These results may help explain why PRC shows early clinical improvement, yet may lead to degenerative arthritis.
Asunto(s)
Artrodesis/métodos , Tendones/fisiopatología , Articulación de la Muñeca/fisiopatología , Articulación de la Muñeca/cirugía , Adulto , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
PURPOSE: Early motion therapy protocols are desirable to reduce wrist stiffness after carpal injuries and distal radius fractures. Based on our assumption that a reduction in wrist tendon forces will be associated with a reduction in radioulnar carpal joint reaction force, the goal of this study was to determine the forearm position at which the wrist tendon forces required to initiate wrist motion were the least. METHODS: We tested 8 fresh-frozen cadaver forearms in a wrist and forearm motion simulator. In each specimen, we generated a wrist flexion-extension motion and a radioulnar deviation motion by pulling on the wrist flexor and extensor tendons with the forearm in supination, pronation, or neutral. We also performed a wrist flexion-extension motion during active forearm rotation. During each motion, we continuously recorded the forces in the 5 wrist tendons. We used repeated-measure analyses of variance to compare tendon forces. RESULTS: During the wrist flexion-extension motion, the summed peak wrist extensor forces were significantly less with the wrist in forearm supination than with the forearm in neutral or during active forearm rotation. For the summed peak wrist flexor forces, flexor tendon forces were significantly less with the forearm in supination compared with active forearm rotation. The extensor carpi radialis longus and flexor carpi ulnaris forces were significantly less in supination than during active forearm motion. During wrist radioulnar deviation motion, peak extensor carpi ulnaris force was significantly less with the forearm in supination than in neutral, and peak flexor carpi radialis force was significantly less with the forearm in supination than in pronation. CONCLUSIONS: Peak wrist tendon forces were least in the static forearm supinated position. CLINICAL RELEVANCE: To reduce deforming forces on a fresh carpal injury or distal radial fracture, active rehabilitation appears to be best initiated with the forearm held in supination.
Asunto(s)
Antebrazo/fisiología , Pronación/fisiología , Supinación/fisiología , Tendones/fisiología , Muñeca/fisiología , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , RotaciónRESUMEN
PURPOSE: To first determine the structural properties of 6 forearm ligaments and then to create linear and nonlinear analytical models of each ligament from these properties. METHODS: We nondestructively tested the annular ligament, dorsal and palmar radioulnar ligaments, and the distal, central, and proximal bands of the interosseous ligament from 7 fresh cadaver forearms in a servohydraulic testing apparatus. We performed testing with the bone-ligament-bone constructs positioned corresponding to neutral forearm rotation as well as in 45° of supination and 45° of pronation. Based on a mechanical creep test of each ligament, we computed a linear and nonlinear ligament stiffness value for each ligament. We then compared these computed analytical responses to loading with loading data when each ligament was tested at 1.0 and 0.05 mm/s. We analyzed differences among ligaments and forearm positions using 1-way and 2-way analyses of variance. RESULTS: The stiffnesses for the distal band and the dorsal radioulnar ligament were statistically less when the constructs were positioned in supination compared with neutral forearm rotation. At all forearm positions, the linear stiffness of the central band was greater than that for the distal band of the interosseous ligament, the proximal band of the interosseous ligament, and the dorsal radioulnar and palmar radioulnar ligaments. In neutral forearm rotation, the linear stiffness of the central band was statistically greater than the annular ligament. The experimental loading behavior of each ligament was better modeled by a nonlinear stiffness than a linear one. CONCLUSIONS: The central band of the interosseous membrane is the stiffest stabilizing structure of the forearm. Any structure used to replace the central band or other forearm ligaments should demonstrate a nonlinear response to loading. CLINICAL RELEVANCE: In considering a reconstruction for the forearm, the graft used should have a nonlinear response to loading and be one that is similar to the normal, original ligament.