Patrick Weninger

Unstable Distal Radius Fractures in the Elderly Patient—Volar Fixed-Angle Plate Osteosynthesis Prevents Secondary Loss of Reduction

BACKGROUND Because of demographic changes in industrialized countries, signifying a growing population of the aged and a markedly increased life expectancy, the incidence of the distal radius fracture is expected to increase by a further 50% until the year 2030. Osteoporosis characterizes the radius fracture in elderly patients. Primarily weakening metaphyseal bone, osteoporosis renders simple fractures unstable and makes distal bone fixation a challenge. The introduction of fixed-angle plate systems for extension fractures of the radius was evaluated in a prospective study performed at our hospital after selection and acquisition of a new plating system. The focus of our interest was whether a secondary loss of reduction can be prevented by this plating system in the elderly patient. METHODS We reviewed 58 patients aged 75 years or older treated for unstable distal radius fractures using a volar fixed-angle plate. Postoperative management included immediate finger motion, early functional use of the hand, wrist splint used for 4 weeks, and physiotherapy. At the time of follow-up, after a mean period of 13 months (range, 12-15 months), standard radiographic and clinical fracture parameters were measured and final functional results were assessed. RESULTS Bone healing had occurred in all patients at the time of follow-up. On X-rays taken at the time of follow-up, 53 patients (91%) had no radial shortening, 5 patients (9%) had a mean radial shortening occurred during follow-up of only 1.3 mm (range, 1-2 mm) compared with the contralateral side. Comparing the first postoperative X-rays with those taken at final evaluation showed no measurable loss of reduction in the volar tilt or radial inclination. Castaings score yielded a perfect outcome in 25 cases, a good outcome in 30 cases, and an adequate outcome in 3 cases. On an average, the range of motion was reduced by 19% during extension/flexion, by 13% during radial/ulnar deviation, and by 9% in pronation/supination compared with the contralateral side. Grip strength was 55% higher than that of the contralateral side. Eleven patients (19%) reported pain at rest with a mean Visual Analog Pain Scale score of 3.1 (range, 1-6), whereas 30 patients (52%) had pain on load-bearing with a mean Visual Analog Pain Scale score of 3.4 (range, 1-8). The mean disabilities of the arm, shoulder, and hand (DASH) score (Jester A, Harth A, Germann G. J Hand Surg Am. 2005;30:1074.e1-1074.e10) was 28 points. A carpal tunnel syndrome with abnormal nerve conduction velocity was diagnosed in three patients, a rupture of the flexor pollicis longus tendon was seen in one patient. CONCLUSION Fixed-angle plate osteosynthesis at the distal radius in the elderly patient signifies a significant improvement in the treatment of distal radial fractures in terms of restoration of the shape and function of the wrist associated with a low complication rate. This technique with its simple palmar access, allows exact anatomic reduction of the fracture, allows early return to function, and minimizes morbidity in the elderly patient. Secondary correction loss can be prevented by this procedure.

More is not necessarily better. A biomechanical study on distal screw numbers in volar locking distal radius plates.

INTRODUCTION Currently available volar locking plates for the treatment of distal radius fractures incorporate at least two distal screw rows for fixation of the metaphyseal fragment and have a variable-angle locking mechanism which allows placement of the screws in various directions There is, however no evidence that these plates translate into better outcomes or have superior biomechanical properties to first generation plates, which had a single distal screw row and fixed-angle locking. The aim of our biomechanical study was to compare fixed-angle single-row plates with variable-angle multi-row plates to clarify the optimal number of locking screws. MATERIALS AND METHODS Five different plate-screw combinations of three different manufacturers were tested, each group consisting of five synthetic fourth generation distal radius bones. An AO type C2 fracture was created and the fractures were plated according to each manufacturers recommendations. The specimens then underwent cyclic and load-to-failure testing. An optical motion analysis system was used to detect displacement of fragments. RESULTS No significant differences were detected after cyclic loading as well as after load-to-failure testing, neither in regard to axial deformation, implant rigidity or maximum displacement. The fixed-angle single-row plate showed the highest pre-test rigidity, least increase in post-testing rigidity and highest load-to-failure rigidity and least radial shortening. The radial shortening of plates with two distal screw rows was 3.1 and 4.3 times higher, respectively, than that of the fixed-angle single-row plate. CONCLUSION The results of our study indicate that two distal screw rows do not add to construct rigidity and resistance against loss of reduction. Well conducted clinical studies based on the findings of biomechanical studies are necessary to determine the optimal number of screws necessary to achieve reproducibly good results in the treatment of distal radius fractures.

First Experiences With a New Adjustable Plate for Osteosynthesis of Scaphoid Nonunions

BACKGROUND Plate osteosynthesis of the scaphoid, as reported earlier by Ender, has lost its importance in the past few years, after Herberts introduction of the simple and successful technique of screw osteosynthesis. Only in rare cases does one encounter failed healing or instability of the fragments. Even with a vascularized bone chip, it is not always possible to achieve consolidation. Particularly in these situations, poor interfragmentary stability seems to be the reason for failed healing. METHODS Between January 2007 and August 2009, we treated 7 men and 4 women of mean age 37 years (22-53 years) by scaphoid plate osteosynthesis. All the patients had fractures of the waist of the scaphoid with established nonunion persisting for at least 6 months after the causative injury, with wrist pain, weakness, or both. All 11 patients had clinical and radiologic follow-up for at least 6 months. RESULTS All the fractures united at a median time from operation of ∼4 months. All patients reported an improvement in their symptoms and function. The mean DASH score was 28 points. CONCLUSIONS Scaphoid plate osteosynthesis should be regarded as a salvage procedure, and the indication for the procedure should be established accordingly. It is a simple procedure in terms of technique. The plate can be adjusted very well to the anatomic shape of the scaphoid, and one can achieve a high degree of stability, particularly rotational stability.

Results of dynamic treatment of fractures of the proximal phalanx of the hand.

BACKGROUND The treatment of fractures of the proximal phalanx in three-phalanx fingers has for a long time been the domain of conservative static treatment in a plaster cast. After removal of the plaster, there was usually limitation of mobility of the interphalangeal joints. Fractures of the proximal phalanx are managed with conservative functional treatment in our clinic. The aim of this method is to achieve bony healing and free mobility at the same time and not in succession. We evaluated our treatment outcomes in a follow-up study. METHODS The dressing consists of a dorsopalmar plaster splint and a so-called finger splint. The wrist and metacarpophalangeal joints are immobilized with the plaster cast. The wrist is dorsiflexed 30 degrees, and the metacarpophalangeal joints are flexed 70 degrees to 90 degrees. In this intrinsic plus position, the extensor aponeurosis is taut and covers two-thirds of the proximal phalanx, thus leading to firm splinting of the fracture. RESULTS Sixty-five patients (46 men and 19 women) with 78 proximal phalanx fractures were followed up after an average of 23 months (12-69 months). The average age of the patients was 41 years (18-93 years). Among our patients, the ring finger was affected most often, with transverse fractures predominating. As regards the location, fractures in the proximal third were most frequent (51%). All fractures consolidated. Delayed fracture healing or pseudarthrosis was not observed. Sixty-seven fingers (86%) showed full range of motion at follow-up. In 11 cases (14%), there was limitation of finger joint movements, with inhibition of extension of the proximal interphalangeal joint in nine patients up to a maximum of 20 degrees. Two patients had limitation of flexion with a fingertip-palm distance of 1.1 cm. CONCLUSION The aim of functional treatment of proximal phalanx fractures is to achieve bony healing and free mobility at the same time and not in succession. Active exercises in the proximal and distal interphalangeal joints prevent limitations of mobility and the subsequent occurrence of rotational and axial deformities.

Volar fixed-angle plating of extra-articular distal radius fractures--a biomechanical analysis comparing threaded screws and smooth pegs.

BACKGROUND Distal radius fractures represent the most common fractures in adult individuals. Volar fixed-angle plating has become a popular modality for treating unstable distal radius fractures. Most of the plates allow insertion of either threaded locking screws or smooth locking pegs. To date, no biomechanical studies compare locking screws and pegs under axial and torsional loading. METHODS Ten Sawbones radii were used to simulate an AO/OTA A3 fracture. Volar fixed-angle plates (Aptus Radius 2.5, Medartis, Switzerland) with threaded locking screws (n = 5) or smooth locking pegs (n = 5) were used to fix the distal metaphyseal fragment. Each specimen was tested under axial compression and under torsional load with a servohydraulic testing machine. Qualitative parameters were recorded as well as axial and torsional stiffness, torsion strength, energy absorbed during monotonic loading and energy absorbed in one cycle. RESULTS Axial stiffness was comparable between both groups (p = 0.818). If smooth pegs were used, a 17% reduction of torsional stiffness (p = 0.017) and a 12% reduction of minimum torque (p = 0.012) were recorded. A 12% reduction of energy absorbed (p = 0.013) during monotonic loading and unloading was recorded if smooth pegs were used. A 34% reduction of energy absorbed in one cycle (p < 0.007) was recorded if threaded screws were used. Sliding of the pegs out of the distal radius metaphyses of the synthetic bones was recorded at a mean torque of 3.80 Nm ± 0.19 Nm. No sliding was recorded if threaded screws were used. CONCLUSIONS According to the results of this study using Sawbones, volar fixed-angle plates with threaded locking screws alone are mechanically superior to volar fixed-angle plates with smooth locking pegs alone under torsional loading.

Intramedullary nailing of proximal tibia fractures—An anatomical study comparing three lateral starting points for nail insertion

INTRODUCTION Intramedullary nailing is challenging in proximal tibia fractures, associated with high rates of malalignment. To date, no studies report the potential of lateral tibia nail insertion to correct primary valgus malalignment, commonly seen in proximal quarter fractures. MATERIALS AND METHODS 18 fresh-frozen cadaver lower extremities were used to simulate an AO/OTA 41-A3 fracture. Six nails (Expert Tibial Nailing System, Synthes, Salzburg, Austria) were inserted at the lateral third, six nails at the middle third and six nails at the medial third of the lateral tibia plateau. After nail insertion, alignment in the coronal plane was recorded. RESULTS Mean varus malalignment was dependent on the entry point at the lateral tibia plateau. Mean varus malalignment was 16 degrees if nails were inserted at the lateral third, 10 degrees at the middle third and 4 degrees after nail insertion at the medial third. If nails were inserted from the medial third, valgus malalignment was recorded in two specimens. DISCUSSION The effect of correction of coronal malalignment in proximal tibia fractures is dependent on the point of nail entry at the lateral plateau. Primary valgus deformation up to 20 degrees can be corrected by inserting tibia nails at the lateral third of the lateral tibia plateau. Surgeons should be aware of possible varus deformity and valgus malalignment despite lateral nail insertion.

Multidirectional volar fixed-angle plating using cancellous locking screws for distal radius fractures--evaluation of three screw configurations in an extra-articular fracture model.

ZusammenfassungEINLEITUNG: Die palmare winkelstabile Plattenosteosynthese ist mittlerweile ein Standardverfahren für distale Speichenfrakturen. Obwohl eine Vielzahl von Plattensystemen verfügbar ist, gibt es wenig biomechanische Studien zu multidirektionalen Plattensystemen. Das Ziel der vorliegenden Arbeit war es, drei verschiedene Schraubenkonfigurationen anhand eines extra-artikulären distalen Speichenfrakturmodells zu vergleichen. MATERIAL UND METHODIK: An 18 Sawbone-Speichen wurde eine extra-artikuläre AO/OTA 23 A3-Fraktur simuliert (Sawbones, Schweden, Modell# 1027). Am Schaft wurden die Platten angebracht, wie vom Hersteller empfohlen. Drei Gruppen (n = 6) wurden definiert: In Gruppe 1 wurde nur eine distale Schraubenreihe besetzt. In Gruppe 2 wurden zwei distale Schraubenreihen parallel zueinander besetzt, in Gruppe 3 wurden ebenfalls zwei distale Schraubenreihen besetzt, die proximale Reihe jedoch in einem steileren Winkel (30°) zur distalen Reihe. Die Präparate wurden anschließend mit einer servo-hydraulischen Testmaschine axial im elastischen Bereich und last-kontrolliert mit 20 bis 200 N (40 N/s) belastet. Aufgezeichnet wurden die axiale Steifigkeit und der Versagensmodus. ERGEBNISSE: Hinsichtlich der axialen Steifigkeit fanden sich keine signifikanten Unterschiede. Bei jedem Präparat bestand der Versagensmodus in einem plastischen Verbiegen der palmaren Titan-Platte nach Verschluss der Osteotomie. DISKUSSION: Unter Berücksichtigung der Limitationen der Studie, kann die routinemäßige Verwendung von zwei Schraubenreihen parallel oder ansteigend anhand der vorliegenden Daten nicht empfohlen werden.SummaryINTRODUCTION: Volar fixed-angle plating is a popular treatment for unstable distal radius fractures. Despite the availability of plating systems for treating distal radius fractures, little is known about the mechanical properties of multidirectional fixed-angle plates. The aim of this study was to compare the primary fixation stability of three possible screw configurations in a distal extra-articular fracture model using a multidirectional fixed-angle plate with metaphyseal cancellous screws distally. MATERIAL AND METHODS: Eighteen Sawbones radii (Sawbones, Sweden, model# 1027) were used to simulate an extra-articular distal radius fracture according to AO/OTA 23 A3. Plates were fixed to the shaft with one non-locking screw in the oval hole and two locking screws as recommended by the manufacturer. Three groups (n = 6) were defined by screw configuration in the distal metaphyseal fragment: Group 1: distal row of screws only; Group 2: 2 rows of screws, parallel insertion; Group 3: 2 rows of screws, proximal screws inserted with 30° of inclination. Specimens underwent mechanical testing under axial compression within the elastic range and load controlled between 20 N and 200 N at a rate of 40 N/s. Axial stiffness and type of construct failure were recorded. RESULTS: There was no difference regarding axial stiffness between the three groups. In every specimen, failure of the Sawbone-implant-construct occurred as plastic bending of the volar titanium plate when the dorsal wedge was closed. DISCUSSION: Considering the limitations of the study, the recommendation to use two rows of screws or to place screws in the proximal metaphyseal row with inclination cannot be supported by our mechanical data.

Micromotion at the fracture site after tibial nailing with four unreamed small-diameter nails--a biomechanical study using a distal tibia fracture model.

BACKGROUND Intramedullary nailing is the treatment of choice in tibia fractures allowing for closed fracture reduction and internal fixation. Small-diameter nails that preserve the endosteal blood supply act as load-sharing devices after proximal and distal locking. Despite fracture healing is influenced by movements at the fracture gap, no data are available reporting on the micromovements at the fracture site if small-diameter nails were used. METHODS Using a Sawbone distal tibia fracture model, we assessed offset, elastic, plastic, permanent, and overall deformation at the fracture site for four small-diameter tibia nails (Expert, Synthes, Saluburg, Austria; Connex, ITS Spectromed, Lassnitzhöhe, Austria; Versanail, DePuy, Vienna, Austria; T2, Stryker, Vienna, Austria) after mechanical testing with a servohydraulic material testing machine. Cyclic loading was performed with a sinusoidal load of 700 N (+/-600) for 40,000 cycles representing 6 weeks of full weight bearing. RESULTS Offset deformation was significantly higher for the Connex nail when compared with other nails (p < 0.001). Regarding elastic deformation, no significant difference was recorded between the implants. Plastic deformation was significantly lower if the Connex nail was used (0.134 [+/-0.053] mm; p < 0.001). Elastic deformation did not exceed 0.7 mm and plastic deformation did not exceed 0.4 mm. Regarding permanent and overall deformation, no significant difference between the implants was recorded. CONCLUSIONS Considerable deformation at the fracture gap can be assumed even after partial weight bearing with 100 N. Despite comparable material properties, differences in axial micromotion were recorded among the nail types used in this series. The number of distal locking screws (three or four) did not substantially influence the axial movements at the fracture gap.

Anatomical Assessment of the Hoffa Fat Pad During Insertion of a Tibial Intramedullary Nail—comparison of Three Surgical Approaches

BACKGROUND Interlocking nailing is a standard procedure in the surgical treatment of tibial fractures. Despite it has been described to be a safe technique with excellent functional results compared with conservative treatment, a common problem is the development of anterior knee pain. The anatomic relation of Hoffas fat pad with its nociceptors to the nail entry point has not been investigated, yet. METHODS Eighteen formalin-fixed lower cadaver extremities of 11 cadavers (five females, six males) were matched into three groups: three approaches (medial paratendinous, transligamentous, and lateral paratendinous) were performed and the anterosuperior tibial cortex was opened with a cheese cutter. To investigate the relationship of the nail entry point and Hoffas fat pad, the joint capsule was incised, and Hoffas fat pad was exposed and then dissected carefully. Damage to the fat pad was recorded as well as meniscal lesions, cartilage lesions, and ligamentous lesions. After full extension and flexion of the knee joint, the motion of Hoffas fat pad (millimeter) was recorded with a measuring gauge. The zone for safe nail insertion (millimeter square) without any lesion to intra-articular structures was recorded. RESULTS Violation of Hoffas fat pad was recorded if the lateral and transligamentous approach were used. With the medial approach, no damage of the fat pad was recorded. Total mean lateralization of the fat pad from extension to flexion over 90 degrees was 18.5 mm compared with its location in the fully extended knee. The safe zone for nail insertion without violation of menisci, cartilage, or ligaments was a triangle in the posteromedial aspect of the Hoffa with a mean dimension of 19.4 mm2. CONCLUSION On the basis of our results, we can recommend the nail insertion via a medial paratendinous surgical approach to avoid injuries to the Hoffa fat pad and to menisci, cartilage, and ligaments.

Factors influencing interlocking screw failure in unreamed small diameter nails - A biomechanical study using a distal tibia fracture model

BACKGROUND Unreamed tibia nails with small diameters are increasingly used for fracture fixation. However, little is known about the fatigue strength of proximal and distal interlocking screws in those nails. To date, no data are available reporting on mechanical differences of solid compared to cannulated tibial nails. The aim of this study was to assess the fatigue strength of proximal and distal interlocking screws of solid and cannulated small diameter tibia nails. METHODS We created a distal tibia fracture model (AO/OTA 43 A3) using 16 Sawbones. After fracture stabilization with one of four different nail types (Expert Tibial Nail, VersaNail, T2 Tibial Nailing System, Connex), mechanical testing was performed in three loading series (40,000 cycles each) with incremental loads. Timing and type of interlocking screw failure were assessed. FINDINGS Interlocking screw failure was observed significantly earlier (after a mean interval of 57,042 cycles) in cannulated tibial nails (VersaNail, T2) compared to solid nails (after a mean interval of 88,415 cycles; P < 0.001). Proximal interlocking screw failure was recorded if oblique screws were used proximally (VersaNail, T2, Connex). No distal interlocking screw failure was recorded in the Connex nail. Two- and three-part fractures of proximal or distal interlocking screws were observed in all specimen. INTERPRETATION Proximal and distal interlocking screw failure has to be considered in small diameter nails in case of delayed fracture healing. To support our results, further experimental studies and clinical series are necessary.