Richard Hammer

Accuracy of radiologic assessment of tibial shaft fracture union in humans.

In a series of 208 tibial shaft fractures, 166 were treated nonoperatively, and of these, 157 had an uncomplicated course of healing. The process of union was followed by repeated noninvasive measurements of fracture stability. Full unprotected weight-bearing was permitted when stability measurements indicated solid union. A group of 127 fractures was evaluated by seven senior radiologists for assessment of the stage of union on anteroposterior and lateral radiographs exposed at the time of measurements of stability. The time for assessment ranged from four to 46 weeks. The radiologic assessment was difficult to correlate to the stability of union; in 55% of unstable fractures, the films pointed to satisfactory union. Of the 93 fractures that were mechanically stable, the films suggested that no union had been achieved in 44%. The probability of a correct radiographic evaluation of stage of union was approximately 0.5. The period required to achieve solid union after tibial shaft fracture is relatively long and unpredictable. Definitions of stage and progress of union are controversial. Conventional roentgenographic examinations as a means of assessing the stage of union are generally inconclusive.

RAB-plate vs Richards CHS plate for unstable trochanteric hip fractures : A randomized study of 233 patients with 1-year follow-up

We prospectively randomized 233 patients with unstable trochanteric hip fractures for treatment with a 120 degrees fixed angle blade-plate having a buttress rod (group A, n 111) or a 135 degrees compression hip screw (group B, n 122). The minimum follow-up time was 1 year. The ratio of technical failure was 9% in group A and 19% in group B (p = 0.06). 79 (87%) fractures in group A and 65 (68%) fractures in group B healed without any complication (p = 0.003). Malunion occurred in 2 cases in group A and in 15 cases in group B (p = 0.002).

RAB-plate versus sliding hip screw for unstable trochanteric hip fractures: stability of the fixation and modes of failure--radiographic analysis of 218 fractures.

BACKGROUND The sliding hip screw has gained considerable acceptance in the treatment of unstable trochanteric fractures. However, the new type of 120 degrees fixed angle blade-plate with a buttress rod (RAB-plate) showed encouraging clinical results. The purpose of this study was to assess stability of fixation and analyze modes of failure in unstable trochanteric hip fractures treated with these devices. METHODS A retrospective radiographic review of 218 unstable fractures was performed. Linear and angular displacements of the major fragments and implant migration into the femoral head during healing were assessed. Additionally, adequacy of the reduction and the location of the implant within the femoral head as predictors of fixation failure were evaluated. RESULTS The postreduction neck-shaft angle was maintained in the majority of the fractures in both groups. However, there was a significantly higher incidence of varus angulation by 10 degrees or more by the completion of healing among fractures treated with the sliding hip screw (p = 0.04). There was no statistically significant difference in vertical migration of the device into the femoral head between the implants used (p = 0.3). There was a significant relationship between failure of the fixation and varus reduction (p = 0.04) as well as screw/neck angle deviation more than 20 degrees in the lateral projection (p = 0.005) or if the implant was in a superior or posterior position (p = 0.02). CONCLUSION The RAB-plate provided a more stable fixation, especially with regard to maintained postoperative alignment. However, positive predictors for fixation failure were identical for both devices. Here, the screw/neck angle deviation has had the strongest significance for prediction of fixation failure.

Team approach to tibial fracture: 37 consecutive Type III cases reviewed after 2-10 years

During a 10-year period, we managed 35 patients with 37 cases of Type III open tibial fractures, 15 cases within 1 week and 22 as late referrals. In all cases, simultaneous assessment and management by a microvascular and an orthopedic surgeon were mandatory throughout the treatment period. 6 of the 15 acute cases had a primary amputation. Of the remaining 31 cases, limb salvage was possible in 27. 31 flaps, pedicle and microvascular free flaps were used. Major complications occurred in 6 cases, but in 27 cases infection-free solid union was obtained. At long-term follow-up, average 5 years, the function was good or acceptable in 23 cases. We conclude that: (1) patients with Type III tibial injuries should preferably be transferred within a week after injury to a hospital where major reconstructive procedures are commonly performed, (2) early soft tissue coverage is essential in the management of these injuries, (3) unilateral external fixation should be the preferred technique of stabilization, and, finally, (4) plastic surgery expertise is important in management of severe tibial fractures.

Spontaneous Subcapital Femoral Neck Fracture After Healed Trochanteric Fracture

Two hundred thirty-three patients with an unstable trochanteric hip fracture were randomized prospectively for stabilization with a fixed angle blade plate or a compression hip screw. Twenty patients had the implant removed after the fracture was healed (average, 20.5 months; range, 12–42 months). In seven of these 20 patients, a spontaneous fracture of the femoral neck occurred at an average of 19 days after implant removal. Four of the these seven patients had been treated with the fixed angle blade plate and three with the sliding screw plate. The histologic examination of three specimens was inconclusive. The authors have not observed subcapital fracture among patients whose implants were not removed. The mechanism behind this complication is unknown.

Evaluation of fracture stability: A mechanical simulator for assessment of clinical judgement

To test the surgeons clinical ability to detect small movements in fractures, a simulator with elastic behaviour was constructed. The bending moment required to produce a certain deflection was adjusted at four different levels. With the lowest stiffness, all surgeons in the test series reported that the fracture was unstable at a deflection of 3-4 degrees. With increasing stiffness, an increase in stability was reported--the registered deflection, however, was always 3-4 degrees. These observations confirm that manual tests of fracture stability are uncertain.

Attempted unreamed nailing in tibial fractures: A prospective consecutive series of 55 patients

We evaluated the possibility of unreamed insertion of an intramedullary nail (IMN) in a consecutive series of 55 tibial shaft fractures in 55 patients (30 men). 43 fractures were closed and 12 fractures were open. All surgeons involved were instructed to try unreamed insertion primarily. Selection of nail diameter was based on measurements of the narrowest part of the medullary canal on preoperative AP- and lateral radiographs, with a millimeter-ruler. Of the 25 cases where a 9 mm nail was chosen, 10 were impossible to insert without reaming. An 8 mm nail was selected in the remaining 30 cases, and here 10 required reaming. Mean time-to-union was 4.2 months. Delayed union was noted in 9 patients of whom 6 had been stabilized with an unreamed nail. The concept of unreamed insertion must be questioned since this could be done in only 35 patients and, in addition, we were not able to demonstrate any significant differences in time-to-union in fractures stabilized with an unreamed or a reamed nail. Implant failures were seen in 5 patients, all stabilized with an 8 mm nail. Failure of interlocking screws did not affect the final outcome. However, a possible combination of screw breakage and healing disturbances may lead to the need for more complex surgical procedures. Due to these reasons and the fact that the 8 mm nail could not be inserted unreamed in 10 of 30 patients, we stopped using the 8 mm nail.

A new device for external fixation

Using a ball-and-socket joint model, the optimal mechanical design of a simple universal ball joint was established. The maximum resistive moment was 70-72 Nm for a tightening torque moment of 5 Nm, their ratio being 14. The corresponding ratios for the Hoffmann universal ball joint and Orthofix are 1.0-4.3 and 1.1-1.6, respectively. A complete unilateral frame consists of two ball joints and one square connecting tube. Full-frame behavior under external loads was tested in the three principal planes and in torsion. Compared with a Hoffman quadrilateral system, the new system was four times more rigid in the anteroposterior plane, similar in axial load and lateral bending, and 64 percent more rigid in torsion.

Strength of union in human tibial shaft fracture. A prospective study of 104 cases.

In a consecutive prospective series of 104 tibial shaft fractures, the strength at the site of union was observed by a noninvasive technique at regular intervals. Eighty-one patients were male and 23 were female. Six fractures were open, and 13 patients had multiple injuries. The primary treatment was conservative with cast immobilization in 86 patients, external fixation by a quadrilateral system in 14, and open reduction and internal fixation in four. A measure of the strength of union is obtained by calculating a quotient between induced deflection between the fracture fragments and the applied bending moment. By plotting this quotient against time-since-injury, a curve describing the changes in stability can be constructed. With this curve it is possible to define united fracture and normal union, and the differentiation between delayed union and true nonunion is possible. Time-to-union in all 104 patients was 16 +/- 15.2 weeks. In 14 with delayed union, surgical measures intended to promote union could be avoided because repeated measurements indicated progressive increase in stability. Bone grafting was performed in 13 fractures for treatment of nonunion. Statistical analysis based on objective measurement of stability failed to identify a specific factor responsible for delayed union or nonunion.

Improved External Skeletal Fixation for Unstable Fractures

A novel external fixation device (EX-FI-RE) is described with which it is possible to manipulate fracture fragments under complete control of stability. EX-FI-RE is a unilateral, telescopic, single-frame device, consisting of two functionally separate components, the correction unit and the fixation unit. The correction unit allows reduction of angular, parallel, and longitudinal dislocations. Sustained transverse compression of an oblique fracture is a special feature. After reduction has been achieved, pin retainers and transcutaneous pins can be transferred to the fixation unit without change of position of the fracture fragments. Its mechanical behavior under load is analyzed and compared with that of a Hoffman-Vidal Adrey quadrilateral system. In axial loading, the two systems were similar within the loading range of 0-1000 N. In the anteroposterior plane, the stiffness ratio of the EX-FI-RE was significantly higher. In lateral bending and axial loading, the two systems were comparable. The turning moment required to induce a 5 degree angular deformation of the quadrilateral system was 4.8 +/- 0.6 Nm; the corresponding figure for the unilateral system was 8.8 +/- 0.4 Nm. After more than two years of clinical experience with this new device, closed atraumatic reduction, sustained transverse compression, and early weight-bearing were found to promote union. There were no pin tract infections or mechanical failures in more than 70 cases treated.