Osteoarthritis of the carpometacarpal joint of the thumb: a new MR imaging technique for the standardized detection of relevant ligamental lesions.

OBJECTIVE: To assess ligament lesions and subluxations of the carpometacarpal joints of the thumbs (CMC I) of asymptomatic volunteers and of patients with CMC I osteoarthritis using advanced magnetic resonance imaging (MRI). MATERIALS AND METHODS: A total of 20 CMC I joints of 14 asymptomatic volunteers (6× both sides) and 28 CMC I joints of 22 patients (6× both sides) with symptomatic and X-ray-diagnosed osteoarthritis of CMC I joints were studied. During extension, flexion, abduction and adduction of the thumb, the anterior oblique (AOL), intermetacarpal (IML), posterior oblique (POL) and dorsal radial (DRL) ligaments were evaluated using 3-T MRI on two standard planes, and translation of metacarpal I (MC I) was assessed. RESULTS: The MRI demonstrated that ligament lesions of the AOL and IML are frequent. Isolated rupture of the AOL was found in 6 of 28 (21%), combined rupture of the AOL + IML in 5 of 28 (18%) and isolated IML rupture in 4 of 28 (14%) joints. The patients had a significantly increased dorsal translation of MC I during extension with a median of 6.4 mm vs. 5.4 mm in asymptomatic volunteers (p < 0.05). CONCLUSION: MRIs of CMC I in two standardized planes frequently show combined ligament ruptures. The dorsal subluxation of MC I, which is increased in patients, correlates with OA severity based on X-ray and can be quantified by MRI. For joint-preserving surgical procedures and for prosthesis implantation of the CMC I, we recommend performing an MRI in two planes of the thumb-extension and abduction-to evaluate the ligaments and dorsal subluxation of MC I.

Quantified contours of curvature in female index, middle, ring, and small metacarpophalangeal joints.

PURPOSE: To study and quantify the morphology of the curvature of the surfaces of metacarpophalangeal metacarpophalangeal joints and to relate joint morphology to joint function. METHODS: Forty metacarpophalangeal joints of the index, middle, ring, and small fingers from 5 right and 5 left hands were taken from female cadavers. The articulating surfaces of the metacarpal head and the base of the proximal phalanx were copied in a true-to-scale fashion. The hard plaster models were sliced in 7 sagittal and 7 transverse planes. The curvatures of the section contours were determined with circular gauges. Statistical analyses were performed by analysis of variance and paired Student t-tests. RESULTS: In the sagittal plane, the cartilaginous surface of the metacarpal head is divided into 2 functional regions and a third dorsal region that does not articulate with the base of the proximal phalanx. The articulating surface of the base of the proximal phalanx approximates a circle in the midsagittal plane. The mean median sagittal radius of curvature of the dorsal articulating aspect of the metacarpal head (6.9 mm) is 33% smaller than that of the base of the proximal phalanx (10.3 mm). The palmar articulating aspect of the metacarpal head (5.8 mm) is 44% smaller than that of the base of the proximal phalanx (10.3 mm). In the median transverse section, the mean radius of curvature of the metacarpal head (7.3 mm) is 18% smaller than that of the base of the proximal phalanx (8.9 mm). CONCLUSIONS: The data demonstrate the highly significant incongruity in the curvature of the articulating pair. This incongruity provides a joint space with its greatest dimension in the sagittal plane. From a mechanical perspective, the metacarpophalangeal joint mechanically represents a joint with 5 kinematic degrees of freedom: 2 for flexion and extension, 2 for abduction and adduction, and 1 for axial rotation.

Prognostic reliability of the Hawkins sign in fractures of the talus.

OBJECTIVE: To determine the prognostic reliability, sensitivity, and specificity of the Hawkins sign. The Hawkins sign is a subchondral radiolucent band in the talar dome that is indicative of viability at 6 to 8 weeks after a talus fracture. It is visible in the anterior-posterior view, but seldom appears on lateral radiographs. DESIGN: Retrospective study. SETTING: University hospital. PATIENTS AND METHODS: Between January 1995 and December 2000, a total of 41 patients (13 female, 28 male) with displaced talar fractures were operated on in our hospital. Thirty-four patients with a mean age of 35 years (range 12-60) were followed for more than 36 months (range 36-52). The prognostic reliability of the Hawkins sign was studied in 31 of these patients using a two-by-two table. The Ankle-Hindfoot scale of the American Orthopaedic Foot and Ankle Society (AOFAS) was used as an outcome measure. RESULTS: No Hawkins sign was found in the five patients who developed avascular necrosis (AVN) of the talus. In the remaining 26 patients who did not develop AVN, a positive (full) Hawkins sign was observed 11 times, a partially positive Hawkins sign 4 times, and a negative Hawkins sign 11 times. The Hawkins sign thus showed a sensitivity of 100% and a specificity of 57.7%. The Hawkins sign (if present) appeared between the 6th and the 9th week after trauma. Mean [range] AOFAS scores were: Pain, 31 [10-40] out of 40; Function, 39 [14-50] out of 50; and Alignment, 7 [0-10] out of 10. The clinical results were satisfactory. CONCLUSION: The Hawkins sign is a good indicator of talus vascularity following fracture. If a full or partial positive Hawkins sign is detected, it is unlikely that AVN will develop at a later stage after injury.

The movement structure of the mandible and alignment of the neck.

The motion patterns of mandibular points were recorded in vivo in closed free movements of the mandible in the sagittal-vertical plane. The points ran along closed loops, which were evaluated by their area and length. All points whose loops showed areas of the same size regarding the sense of circulation formed straight lines. When the absolute area of the loops was taken into account, a valley with two minima was found in the function "absolute area versus position of the point", the point which showed the deepest minimum tallied with the position of the neuromuscular mandibular rotation axis. The points with loop lengths of same size formed elliptical lines, the perimeter of which was minimal for a point below the condyle. Morphological relations: the row of teeth in the upper jaw was found to be located below the line of minimal path lengths on the straight lines with constant areas, and the cervical spine was found to be arranged along the valley of the minimal absolute areas where the path lengths have their maximum.

The thumb carpometacarpal joint: curvature morphology of the articulating surfaces, mathematical description and mechanical functioning.

PURPOSE: The purpose is to present a mathematical model of the function of the thumb carpometacarpal joint (TCMCJ) based on measurements of human joints. In the TCMCJ both articulating surfaces are saddle-shaped. The aim was to geometrically survey the shapes of the articulating surfaces using precise replicas of 28 TCMCJs. METHODS: None of these 56 articulating surfaces did mathematically extend the differential geometrical neighbourhood around the main saddle point so that each surface could be characterised by three main parameters: the two extreme radii of curvature in the main saddle point and the angle between the saddles' asymptotics (straight lines). RESULTS: The articulating surfaces, when contacting at the respective main saddle points, are incongruent. Hence, the TCMCJ has functionally five kinematical degrees of freedom (DOF); two DOF belong to flexion/extension, two to ab-/adduction. These four DOF are controlled by the muscular apparatus. The fifth DOF, axial rotation, cannot be adjusted but stabilized by the muscular apparatus so that physiologically under compressive load axial rotation does not exceed an angle of approximately ±3°. CONCLUSIONS: The TCMCJ can be stimulated by the muscular apparatus to circumduct. The mechanisms are traced back to the curvature incongruity of the saddle surfaces. Hence we mathematically proved that none of the individual saddle surfaces can be described by a quadratic saddle surface as is often assumed in literature. We derived an algebraic formula with which the articulating surfaces in the TCMCJ can be quantitatively described. This formula can be used to shape the articulating surfaces in physiologically equivalent TCMCJ-prostheses.

The upper ankle joint: Curvature morphology of the articulating surfaces and physiological function.

PURPOSE: The curvature morphology of the articulating surfaces determines the physiological movement pattern. We quantitatively examined the curvature morphology of the tibiotalar articulating surfaces and specified their geometric contact patterns. METHODS: Geometrically equivalent cartographic nets were marked on the talar and tibial articulating surfaces of true-to-scale moldings of 20 human ankle joints (intervals of 5 mm) to relate corresponding articulating units of the surfaces. The corresponding contours of the net lines were compared, and the incongruity of articulating surfaces could thus be quantified locally. RESULTS: All tibial sagittal net lines represented circular arcs. Along the sagittal talar net lines, the curvature radii increased medially from anterior to posterior but decreased laterally. Each net line could be approximated by three circular arcs. Examining these three parts of the talar net lines, the anterior sagittal curvature radii increased from medial to lateral, whereas the posterior radii decreased. The tibial and talar transversal net lines were congruent. The articulation surfaces showed a transversal contact line in every dorsal/plantar joint position. The degree of local congruity was solely ascertained by the incongruity of the corresponding sagittal net lines. The maximal degrees of congruity were found laterally for dorsal flexion, laterally/centrally for neutral joint position, and centrally/medially for plantar flexion. CONCLUSIONS: By the transversal line contact, the contact area is broadened over the articulating surfaces from lateral to medial. In dorsal flexion, compressive loads are mainly transferred by lateral/anterior zones and in plantar flexion by medial/posterior zones of the articulating surfaces. Reconstruction of the transversal contact line is essential.

The morphology of the articular surfaces of biological knee joints provides essential guidance for the construction of functional knee endoprostheses.

PURPOSE: In comparative examinations of kinematics of the knees of humans and pigs in flexional/extensional motion under compressive loads, the significant differential geometric essentials of articular guidance are elaborated to criticise the shaping of the articular surfaces of conventional knee-endoprostheses and to suggest constructional outlines that allow the endoprosthesis to adopt natural knee kinematics. Implantation is discussed with regard to the remaining ligamentous apparatus. METHODS: Twelve fresh pig knee joints and 19 preserved human knee joints were moved into several flexional/extensional positions. In each joint, the tibia and femur were repeatably caught by metal plates. After removing all ligaments, the tibia and femur were again caught in these positions, and their points of contact were marked on both articular surfaces. Along the marker points, a thin lead wire was glued onto each surface. The positions and shapes of the four contact lines were mapped by teleradiography. RESULTS: All contact lines were found to be plane curves. The medial and lateral planes were parallel, thus defining the joint's sagittal plane. In the human knee, as compared to the lateral, the medial femoral contact line was always shifted anteriorly by several millimetres. The tibial contact curve was laterally convex and medially concave. In the pig knees, the lateral and medial contact lines were asymmetrically placed. Both tibial curves were convex. CONCLUSIONS: Both knees represent cam mechanisms (with one degree of freedom) that produce rolling of the articular surfaces during the stance phase. Implantation requires preservation of the anterior cruciate ligament, and ligamentous balancing is disadvantageous.

Do stable multiply injured patients with bilateral femur fractures have higher complication rates? An investigation by the EPOFF study group.

BACKGROUND: Polytrauma patients with bilateral femur shaft fractures are known to have a higher rate of complications when compared with those who have sustained unilateral fractures. The current study tests the hypothesis that the high incidence of posttraumatic complications in patients who do not have a severe head or chest injury is caused by accompanying injuries rather than by the additional femur fracture. METHODS: Inclusion criteria New Injury Severity Score > 16 points; AIS score value of the chest ≤3 points and no severe head injury. Two study groups: a unilateral group (USF group) (n = 146) and a bilateral femur shaft fracture group (BSF group) (n = 19). Endpoints monitored were length of stay in the intensive care unit, duration on a ventilator, and several postsurgical complications (e.g., SEPSIS, acute lung injury). Statistics Fisher's exact test for binary variables, and independent t-tests and regression analyses for continuous indicators of injury severity and clinical outcomes. RESULTS: Patients with bilateral femur fractures had a significantly higher incidence of hemothorax. Moreover, they received blood transfusions more often upon admission, and exhibited a longer ICU stay (p = 0.008). However, this patient group did not exhibit a significantly higher incidence of postsurgical complications (p = 0.1) than those with unilateral fractures. After adjusting for injury severity, no difference in the length of the ICU stay was observed. Bilateral fracture patients who were in an uncertain condition preoperatively had a longer length of stay in the ICU postoperatively (p = 0.002). CONCLUSIONS: In the absence of major head or chest injuries, patients with multiple injuries and bilateral femur shaft fractures have a similar complication rate to polytrauma patients with unilateral fractures. Moreover, an uncertain condition preoperatively was associated with an increased stay in the intensive care unit. The results support the idea that associated injuries rather than the additional femur fracture are responsible for complications during the clinical stay.

Cost analysis of Topical Negative Pressure (TNP) Therapy for traumatic acquired wounds.

Extended traumatic wounds require extended reconstructive operations and are accompanied by long hospitalizations and risks of infection, thrombosis and flap loss. In particular, the frequently used Topical Negative Pressure (TNP) Therapy is regarded as cost-intensive. The costs of TNP in the context of traumatic wounds is analyzed using the method of health economic evaluation. All patients (n=67: 45 male, 22 female; average age 54 y) with traumatically acquired wounds being treated with TNP at the university hospital of Goettingen in the period 01/01/2005-31/12/2007 comprise the basis for this analysis. The concept of activity-based costing based on clinical pathways according to InEK (National Institute for the Hospital Remuneration System) systematic calculations was chosen for cost accounting. In addition, a special module system adaptable for individual courses of disease was developed. The treated wounds were located on a lower extremity in 83.7% of cases (n=56) and on an upper extremity in 16.3% of cases (n=11). The average time of hospitalization of the patients was 54 days. Twenty-five patients (37.31%) exceeded the "maximum length of stay" of their associated DRG (Diagnosis Related Groups). The total PCCL (patient clinical complexity level = patient severity score) of 2.99 reflects the seriousness of disease. For the treatment of the 67 patients, total costs were $1,729,922.32 (1,249,176.91 euro). The cost calculation showed a financial deficit of $-210,932.50 (-152,314.36 euro). Within the entire treatment costs of $218,848.07 (158,030.19 euro), 12.65% per case were created by TNP with material costs of $102,528.74 (74,036 euro), representing 5.92% of entire costs. The cost of TNP per patient averaged $3,266.39 (2,358.66 euro). The main portion of the costs was not - as is often expected - due to high material costs of TNP but instead to long-term treatments. Because of their complexity, the cases are insufficiently represented in the lump-sum calculation of the InEK. A differentiated integration of complex TNP-treatment in the DRG system (e.g., as an expanded DRG I98Z) would be a step towards cost recovery. In addition, the refunding of outpatient TNP-treatment would lead to enhanced quality of life for the patients and to a reduction of hospital costs and length of stay.

Migration of the instantaneous axis of motion during axial rotation in lumbar segments and role of the zygapophysial joints.

The biomechanical role of the zygapophysial joints was investigated for axial rotations of lumbar segments by recording the positions of the instantaneous helical axis (IHA) against the axial rotational angle and by relating these IHA-positions to anatomical landmarks. Cyclically varying pure axial moments were applied to 3 L1/L2, 7 L3/L4 and 3 L4/L5 segments. There were 800 segment positions per cycle taken by a custom-made high precision 3D-position measuring system. In intact segments IHA-migration reached from one zygapophysial joint to the other IHA-paths came up to 10-60 mm within small angular intervals (±1 deg). After removing the right joints, IHA-migration remained comparable with that of intact segments only for segment positions rotated to the right. Rotation to the left, however, approximately yielded stationary IHA-positions as found after resection of both joints. Hence, IHA-migration is determined by the joints already for small rotational angles. Each type of segment showed a typical pattern of IHA-migration.

Long-term effects of saw osteotomy versus random fracturing on bone healing and remodeling in a sheep tibia model.

This article is about the evaluation of possible differences in biomechanical or histomorphological properties of bone healing between saw osteotomy and random fracturing after 6 months. A standardized, 30 degrees oblique monocortical saw osteotomy of sheep tibia was carried out, followed by manual fracture completion of the opposed cortical bone. Fixation was performed by bridge plating (4.5 mm, LCDCP, broad). X-rays were taken immediately after surgery and at the end of the study. Polychrome fluorescent staining was performed according to a standardized protocol in the 2nd, 4th 6th, 10th, 14th, 18th, 22th and 26th week. Ten sheep were comprehensively evaluated. Data for stiffness and histomorphology are reported. The average bending stiffness of the operated bone was higher (1.7 (SD 0.3) with plate (MP) vs. 1.5 without plate) than for the intact bone (1.4 (SD 0.2), though no significant differences in bending stiffness were observed (P>0.05). Fluorescence staining revealed small numbers of blood vessels and less fragment resorption and remodeling in the osteotomy gap. Bone healing after saw osteotomy shows a very close resemblance to 'normal' fracture healing. However, vascular density, fragment resorption, fragment remodeling, and callus remodeling are reduced at the osteotomy.

The Elastic Bridge Plating of the Forearm Fracture: A Prospective Study.

Rigid plate osteosynthesis with compression is still the treatment of choice for forearm fractures to gain anatomic reposition, provide proper rotation and avoid a bridging callus. Due to necessary operative dissection there is a serious risk for infection and malunion. Based on good clinical results with elastic bridge plating at femur, humerus and tibia, this technique was also started to be used for forearm fractures in our clinic in 1995. In a prospective study, 86 of 124 consecutive patients at the age of 35.2 ± 14.7 years with 129 diaphyseal fractures of the radius or ulna (AO: 37 type A, 36 type B, 13 type C) were analyzed between January 1998 and December 2003. All fractures were stabilized by bridge plating. Radiographic union and clinical outcome were documented. Of the 129, 122 diaphyseal fractures (94.5%) healed within 10.2 ± 3.4 weeks without complications (no nerve lesions, nonunion, synostosis callus). One re-osteosynthesis, one secondary lag screw, and five cancellous bone grafts were necessary before final healing. About 79.1% of the patients had a perfect clinical outcome; 17.4% had additional severe injuries of the same arm. Bridge plating without interfragmentary compression is a reliable surgical procedure even for forearm fractures with low risk of infection and nonunion.

Morphology of the interphalangeal joint surface and its functional relevance.

PURPOSE: To study and to clarify the curvature morphology of the articular surfaces of the proximal interphalangeal (PIP) joint and to relate joint morphology and joint kinematics. METHODS: The radii and centers of curvature of 40 PIP joints were determined by sagittal and transverse intersections of highly precise replicas that were prepared by dental methods. RESULTS: The PIP joint is proved to be a nonconforming joint: the articular surface of the proximal end of the middle phalanx has lesser curvatures than the condyles of the proximal phalanx. In intersections through the apex of the radial and ulnar condyles, the measured differences of the radii between the articular surfaces of the PIP joint were sagittally about 30% and transversely about 49% of the respective radii of the condyles. Incongruity of the joint results in 2 morphologically given axes for extension respective to flexion: (1) an axis given by the articular surfaces of both condyles of the proximal phalanx; and (2) a second axis given by the articular surface of the proximal end of the middle phalanx. Both articulating surfaces have 2 contact points in the transverse plane, one each, central to the apex of radial and ulnar condyles, respectively. In the middle of the joint, in the intercondylar groove, a small joint cavity was present in 37 of 40 joints. CONCLUSIONS: The physiological incongruity of the 2 articular surfaces of the PIP joint was defined quantitatively. This allows the derivation of a theoretical model for PIP joint function that explains the kinematics and mechanical stability of the joint as well as the lubrication and nutrition of the cartilaginous structures.

Clinical results of absorbable plates for displaced metacarpal fractures.

PURPOSE: To present the clinical results of a study of unstable metacarpal fractures treated with absorbable plates. METHODS: Between July 2004 and June 2006, 12 patients (14 fractures) who presented with displaced, unstable, metacarpal fractures had open reduction and internal fixation. The overall clinical follow-up results and radiographic controls at 6, 12, and 26 weeks after surgery are reported. The clinical outcome was assessed by the Disabilities of the Arm, Shoulder, and Hand score and the visual analogue pain scale. RESULTS: The involved fingers showed an average final total active motion of 234 degrees (range, 220 degrees-265 degrees). No deformity of rotation>5 degrees was observed in any patient in the clinical follow-up evaluation. One patient had a loss of reduction with a palmar angle of the metacarpal axis of 20 degrees in the sagittal plane. A second patient with secondary loss of reduction required surgical revision, at which time internal fixation was performed by using a titanium plate. Complications included keloid formation and prolonged soft-tissue swelling for more than 6 weeks in 3 patients. No wound margin necrosis, infection, pseudarthrosis, sinus formation, or osteolysis was observed. Bone consolidation was achieved reliably within 6 weeks both clinically and radiologically. The Disabilities of the Arm, Shoulder, and Hand score results 6 weeks after surgery were an average of 30 points compared with 13 after 12 weeks and 3 points after 26 weeks. The visual pain scale showed mean values of 18 after 6 weeks, 2 after 12 weeks, and 0.2 after 26 weeks. CONCLUSIONS: Absorbable plates are suitable for use in hand surgery and allow early range of motion in combination with an additional orthosis of the hand (as described) for 3 weeks. In the early and medium-term postoperative course, no osteolysis or sterile sinus formation was observed. Metal plates are still the gold standard; however, surgical implants made of amorphous copolymer of L-lactide and glycolic acid in combination with an orthosis constitute a useful and reliable means of metacarpal fracture treatment. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Impact of the method of initial stabilization for femoral shaft fractures in patients with multiple injuries at risk for complications (borderline patients).

OBJECTIVES: The timing of definitive fixation for major fractures in patients with multiple injuries is controversial. To address this gap, we randomized patients with blunt multiple injuries to either initial definitive stabilization of the femur shaft with an intramedullary nail or an external fixateur with later conversion to an intermedullary nail and documented the postoperative clinical condition. METHODS: Multiply injured patients with femoral shaft fractures were randomized to either initial (<24 hours) intramedullary femoral nailing or external fixation and later conversion to an intramedullary nail. Inclusion: New Injury Severity Score >16 points, or 3 fractures and Abbreviated Injury Scale score > or =2 points and another injury (Abbreviated Injury Scale score > or =2 points), and age 18 to 65 years. Exclusion: patients in unstable or critical condition. Patients were graded as stable or borderline (increased risk of systemic complications). OUTCOMES: : Incidence of acute lung injuries. RESULTS: Ten European Centers, 165 patients, mean age 32.7 +/- 11.7 years. Group intramedullary nailing, n = 94; group external fixation, n = 71. Preoperatively, 121 patients were stable and 44 patients were in borderline condition. After adjusting for differences in initial injury severity between the 2 treatment groups, the odds of developing acute lung injury were 6.69 times greater in borderline patients who underwent intramedullary nailing in comparison with those who underwent external fixation, P < 0.05. CONCLUSION: Intramedullary stabilization of the femur fracture can affect the outcome in patients with multiple injuries. In stable patients, primary femoral nailing is associated with shorter ventilation time. In borderline patients, it is associated with a higher incidence of lung dysfunctions when compared with those who underwent external fixation and later conversion to intermedullary nail. Therefore, the preoperative condition should be when deciding on the type of initial fixation to perform in patients with multiple blunt injuries.