Die Stabilität von distalen Radiusfrakturen mit volaren winkelstabilen Plattenosteosynthesen

Background

Distal radius fractures continue to show significant complication rates after operative treatment with locked plating. Failure occurs by screw loosening or screw penetration in the distal fragment. Placement of additional screws may enhance the stiffness of fracture fixation. The aim of this study was to determine the fatigue properties of different screw configurations in distal radius plate osteosynthesis with biomechanical tests and finite element analysis (FEA).

Material and methods

Unstable distal radius fractures were created in 12 human cadaveric bone specimens and were fixed with volar locking plates. Group 4SC was fixed with four screws in the distal row and group 6SC with two additional screws the row below. Dynamic loading was applied physiologically. The radial shortening, the angulation of the distal fragment and the failure mechanism were determined by experimental tests and were further elucidated by FEA.

Results

Group 6SC showed a significantly lower radial shortening and inclination. Breakage of the screws within the plate was noted in group 4SC, while moderate screw penetration was observed in group 6SC. FEA confirmed the biomechanical tests. In group 4SC elevated von Mises strain in the locking mechanism explained the inclination of the screws and the distal fragment. The elastic strain in group 6SC was increased at the screw-bone interface which explained the resulting screw penetration.

Conclusion

The failure mechanism in volar plating of distal radius fractures depended on the number of screws and their configuration. Using two more screws increases construct stiffness and angular stability under dynamic loading. However, increased stiffness also promoted screw penetration mainly in osteoporotic bone. Compared to screw penetration, loss of reposition and inclination of the distal fragment observed in the 4SC configuration is more likely to result in clinical complications.     

Calcium phosphate cement augmentation after volar locking plating of distal radius fracture significantly increases stability

Purpose

Distal radius fractures represent the most common fractures in adults. Volar locking plating to correct unstable fractures has become increasingly popular. Although reasonable primary reduction is possible in most cases, maintenance of reduction until the fracture is healed is often problematic in osteoporotic bone. To our knowledge, no biomechanical studies have compared the effect of enhancement with biomaterial on two different volar fixed-angle plates.

Methods

Human fresh-frozen cadaver pairs of radii were used to simulate an AO/OTA 23-A3 fracture. In a total of four groups (n = 7 for each group), two volar fixed-angle plates (Aptus 2.5 mm locking fracture plate, Medartis, Switzerland and VA-LCP two-column distal radius plate 2.4, volar, Synthes, Switzerland) with or without an additional injection of a biomaterial (Hydroset Injectable HA Bone Substitute, Stryker, Switzerland) into the dorsal comminution zone were used to fix the distal metaphyseal fragment. Each specimen was tested load-controlled under cyclic loading with a servo-hydraulic material testing machine. Displacement, stiffness, dissipated work and failure mode were recorded.

Results

Improved mechanical properties (decreased displacement, increased stiffness, decreased dissipated work) were found in both plates if the biomaterial was additionally injected. Improvement of mechanical parameters after biomaterial injection was more evident in the Synthes plate compared to the Aptus plate. Pushing out of the screws was noticed as a failure mode only in samples lacking supplementary biomaterial.

Conclusions

Injection of a biomaterial into the dorsal comminution zone increases stability after volar locking plating of distal radius fractures in vitro.     

Distal radius fractures and the volar lunate facet fragment: Kirschner wire fixation in addition to volar-locked plating

Background

The volar lunate facet fragment of a distal radius fracture may not be stabilized with volar-locked plating alone due to the small size and distal location of the fragment. Identification and stabilization of this small fragment is critical as unstable fixation may result in radiocarpal and radioulnar joint subluxation. The addition of spring wire fixation with volar plating can provide stable internal fixation of this critical fracture fragment.

Methods

A retrospective review (2006–2011) identified nine patients with distal radius fractures with an associated volar lunate facet fragment that were treated with volar-locked plating and spring wire fixation of the volar lunate facet fragment. Radiographic indices, range of motion, grip strength, and postoperative Patient-related wrist evaluation (PRWE) scores were obtained to assess pain and function.

Results

All distal radius fractures healed, and the volar lunate facet fragment reduction was maintained. The mean follow-up was 54 weeks. Mean active range of motion was 46° wrist flexion, 51° wrist extension, 80° pronation, and 68° supination. The mean grip strength was 21 Kg, achieving 66 % of the uninjured limb. The average PRWE score was 17. No patient required removal of hardware or had evidence of tendon irritation.

Conclusions

The addition of spring wire fixation to volar-locked plating provided stable fixation of the volar lunate facet fragment of distal radius fractures without complication. This technique addresses a limitation of volar-locked plating to control the small volar lunate facet fragment in distal radius fractures otherwise amenable to volar plating.

Level of Evidence

A retrospective case series, Level IV.     

Volar locking plate fixation of distal radius fractures: use of an intra-operative ‘carpal shoot through’ view to identify dorsal compartment and distal radioulnar joint screw penetration

Introduction

We report our experience using a ‘carpal shoot through’ view of the distal radius to identify dorsal compartment screw penetration intra-operatively when performing volar plating of the distal radius.

Methods

A prospective study of 42 patients (mean age 56 years) with acute distal radius fractures treated with open reduction internal fixation was undertaken. Surgical fixation was performed using a volar locking plate in all patients. After plate application, inclined posteroanterior and lateral radiographs were taken followed by the carpal shoot through view.

Results

In six cases (14 %), the carpal shoot through view revealed dorsal screw protrusion, which was not detectable on standard PA and lateral views. In one case, a screw had penetrated the distal radioulnar joint (DRUJ), which was only apparent on the shoot through view. The overall screw exchange rate was 17 %.

Conclusions

Using the hand and carpus to minimise the contrast in X-ray penetration, the dorsal cortex of the distal radius may be imaged intra-operatively and dorsal compartment screw penetration detected in cases with significant multifragmentation when screw measurement is difficult. This view potentially reduces the risk of post-operative pain and extensor tendon injury and also provides excellent visualisation of the DRUJ.     

Outcomes and complications of fractures of distal radius (AO type B and C): volar plating versus nonoperative treatment

Objectives

Management of AO type B and C fractures of the distal radius is controversial. This study compares outcomes and complications of AO type B and C fractures of the distal radius treated with volar locked plating and nonoperative methods.

Materials and methods

Sixty-four patients with fractures of the distal radius (AO type B and C) were included in this study, according to inclusion criteria, and were allocated to the volar plating group or nonoperative group by alternate randomization: 32 patients with odd numbers went into the nonoperative group and the other 32 with even numbers went into the volar plating group. Patients in the nonoperative group were managed with closed reduction of the fracture and plaster cast application under an image intensifier. Those in the volar plating group were managed by open reduction and fixation with a volar locked plate. Preoperative and postoperative serial clinico-radiological follow-up was done. The range of movement, grip strength, functional outcome scores and radiological parameters were compared. Student’s t-test was used for statistical analysis with significance at p < 0.05.

Results

Range of movement and functional scores were significantly (p < 0.001) better in the volar plating group, but the difference in ulnar variance and radial and ulnar deviation was insignificant as compared to the nonoperative group. At 24 months follow-up, the nonoperative group had significantly more cases with malunion, articular incongruity and osteoarthritis.

Conclusion

In cases of AO type B or C fractures of the distal radius, volar locked plating provides anatomical stable fixation and early mobilization with better clinico-radiological outcome as compared to conservative treatment.     

Intraoperative evaluation of dorsal screw prominence after polyaxial volar plate fixation of distal radius fractures utilizing the Hoya view: a cadaveric study

Background

The irregular nature of the dorsal surface of the distal radius makes it difficult to detect prominent screws with volar plate fixation for distal radius fractures using standard fluoroscopic images. This study evaluates the accuracy of a new radiographic method, the Hoya view, for the assessment of dorsal cortical screw penetration with volar plate fixation.

Methods

Eight cadaveric upper extremities underwent application of a volar distal radius plate with polyaxial locking screws placed distally. Utilizing a mini C-arm, lateral and Hoya views were obtained with notation of any dorsal cortical screw prominence. Dissection of the cadavers was then performed for direct visualization of screw prominence. The screws were then exchanged sequentially for screws 2-mm longer than their initial measurements with repeated imaging and direct visualization.

Results

The Hoya view revealed that 9.4 % of the screws penetrated the dorsal cortex with an average screw prominence of 1.08 mm (range 0.5–2 mm). None of the six prominent screws were detected with lateral views. With the Hoya view, six of six prominent screws were identified. With locking screws exchanged for screws 2-mm longer, 76.6 % of the screws had violated the dorsal cortex; of these, 24.5 % were detected with lateral imaging versus 100 % with the Hoya view.

Conclusions

This study supports the intraoperative use of the Hoya view to evaluate screw length and dorsal cortical screw penetration in volar plate fixation of distal radius fractures. However, this view may be difficult to obtain in patients with limitations in elbow or shoulder range of motion.     

Nicht gelenküberbrückender Fixateur externe vs. palmare winkelstabile Plattenosteosynthese in der Behandlung der distalen extraartikulären Radiusfraktur

Aim/Purpose

The aim of operative treatment of distal radius fractures is to achieve anatomic restoration and stable fixation allowing early wrist movement. The extraarticular radio-radial fixator may provide both. In a prospective randomized trial, the nonbridging external fixator was compared with open reduction and internal fixation by volar fixed angle plating.

Methods

A total of 62 patients with extraarticular fractures of the distal radius were included in a prospective randomized trial: 33 patients were treated by external fixation and 29 patients by internal plate fixation. Follow-up examinations were carried out 8 weeks, 6 months, and 1 year after surgery.

Results

The time for surgery using the nonbridging external fixator was significantly less (41 minutes) than using volar plating (56 minutes), whereas intraoperative fluoroscopy time turned out to be twice as long (2 minutes). The functional outcome was good or excellent in both treatment groups. Eight weeks after surgery, patients with nonbridging external fixation presented with significantly less grip strength (26% of the contralateral hand) compared to patients with volar plating (48% of the contralateral hand). The restoration of the physiological volar tilt was achieved more precisely by external fixation. The results of the SF-36 health survey did not show any significant differences between both groups.

Conclusion

Nonbridging external fixation is a good alternative treatment option to open reduction and volar plating. The minimally invasive technique allows for anatomical restoration and safe reduction permitting early range of motion. The clinical and radiological results are good to excellent accompanied by a low rate of complications.     

Feasibility study on the potential of a spiral blade in osteoporotic distal femur fracture fixation

Introduction

Osteoporotic fractures of the distal femur (primary as well as periprosthetic) are a growing problem in today’s trauma and orthopaedic surgery. Therefore, this feasibility study should identify the biomechanical potential of a (commercially available) spiral blade in the distal femur as compared to a single screw without any additional plate fixation. Additionally, the influence of cement augmentation was investigated.

Materials and methods

An artificial low density bone model was either instrumented with a perforated spiral blade or a 5 mm locking screw only. Additionally, the influence of 1 ml cement augmentation was investigated. All specimens were tested with static pull-out and cyclic loading (50 to 250 N with an increment of 0.1 N/cycle).

Results

In the non-augmented groups, the mean pull-out force was significantly higher for the blade fixation (p < 0.001). In the augmented groups, the difference was statistically not significant (p = 0.217). Augmentation could increase pull-out force significantly by 72 % for the blade and 156 % for the screw, respectively (p = 0.001). The mean number of cycles to failure in the non-augmented groups was 12,433 (SD 465) for the blade and 2,949 (SD 215) for the screw, respectively (p < 0.001). In the augmented group, the blade reached 13,967 (SD 1,407) cycles until failure and the screw reached 4,413 (SD 1,598), respectively (p < 0.001).

Conclusion

The investigated spiral blade was mechanically superior, significantly, as compared to a screw in the distal femur. These results back up the further development of a distal femoral blade with spiral blade fixation for the treatment of osteoporotic distal femur fractures.     

Improving accuracy and confidence in distal radius volar plate screw placement through supplemental radiography: examining specialty, education, and experience levels

Background

The purpose of this study was to assess the extent to which a supplemental radiographic view increases accuracy and confidence ratings when determining screw placement in volar plating of distal radius fractures for evaluators of different specialties and experience levels.

Methods

Thirty-four distal radius fractures treated with volar plate fixation were imaged using standard AP and lateral, and supplemental lateral tilt views. Each case was then evaluated for penetration of distal screw tips into the articular space. Sixty-five physicians then completed a two-phase analysis and survey of these cases. In the first phase, presentation consisted only of AP and lateral views; in the second, the lateral tilt view was added. Participants were asked to determine whether distal screws penetrated the joint and rate their confidence in the determination. Assessments were scored for correctness; changes in accuracy and confidence levels between phases were analyzed using paired t tests. Comparisons between groups were performed by ANOVA.

Results

Supplementation increased accuracy and confidence in all position, specialty, and experience groups. Confidence scores were significantly higher following evaluation of three views versus two views. Residents exhibited the greatest improvements in accuracy and confidence. For first-phase (standard view) assessments, accuracy scores were significantly better for attendings with less than 10 years post-fellowship experience than those with more.

Conclusions

A supplemental view of the distal radius combined with AP and lateral views significantly improves the ability of all evaluators, regardless of specialty or training level, to correctly assess placement of fixation screws. The greatest improvements are seen for resident trainees.     

Flexor tendon injuries following plate fixation of distal radius fractures: a systematic review of the literature

Background

Flexor tendon rupture is a rare but major complication associated with volar plate fixation of distal radius fractures.

Materials and methods

We performed a systematic review to evaluate the demographics, clinical profile, treatment and outcome of flexor tendon rupture following volar plate fixation of distal radius fracture. Electronic searches of the MEDLINE, EMBASE, and Cochrane databases for systematic reviews and conference proceedings were performed. Studies were included if they reported flexor tendon rupture (partial or complete) as a complication of distal radius fracture plating (all levels of evidence).

Result

Our search yielded 21 studies. There were 12 case reports and 9 clinical studies. A total of 47 cases were reported. There were 11 males and 23 females (n = 16 studies). The mean age was 61 years old (range 30–85). The median interval between the surgery and flexor tendon rupture was 9 months (interquartile range, 6–26 months). Twenty-nine plates were locking and 15 were nonlocking (n = 20 studies). FPL was the most commonly ruptured tendon (n = 27 cases, 57 %), with FDP to index finger being the second most common (n = 7 cases, 15 %). Palmaris longus tendon graft and primary end-to-end repair were the most common surgical methods used in cases of FPL tendon rupture.

Conclusion

Flexor tendon rupture is a recognised complication of volar plating of distal radius fracture. Positioning of the plate proximal to the “watershed” line and early removal of the plate in cases with plate prominence or warning symptoms can reduce the risk of this complication.     

Volare winkelstabile vs. dorsale Plattenosteosynthese bei der distalen Radiusextensionsfraktur

Introduction

This study investigated the radiographic and functional outcomes of two different methods for treating fractures of the distal part of the radius.

Patients and methods

In a prospective controlled study patients with forearm fractures were randomized by age, handedness, and fracture type.

Results

The study included 120 patients, with a mean age of 66 years. Forty-nine percent of the fractures were extraarticular, and 51% were intraarticular. In the group treated with volar locking compression plates, six patients needed operative decompression of the median nerve and one needed reconstruction of the extensor pollicis longus (EPL) tendon. The group with dorsal plating had three complications requiring operative treatment: one deep infection, one dislocation of the plate, and one reconstruction of the EPL tendon. The radiological results for the Stewart 1 score showed 68% excellent results in volar locking compression plating compared with 57% in dorsal plating. Regarding functional outcome, 48% with volar plating showed excellent results compared with 22% with dorsal plating, as measured by the Stewart 2 score.

Conclusion

Despite significant advantages of the volar locked compression plating, subjective satisfaction did not differ between the two groups.     

Non-bridging external fixation employing multiplanar K-wires versus volar locked plating for dorsally displaced fractures of the distal radius

Background

The aim of this study was to compare non-bridging external fixation to palmar angular stable plating with respect to radiological outcome, wrist function, and quality of life.

Methods

One hundred and two consecutive patients (mean age: 63 years) were enrolled in the study. Fifty-two patients were randomized for plate osteosynthesis (2.4 mm, Synthes), 50 patients received non-bridging external fixation (AO small fixator). Objective (range of motion, grip strength), patient rated outcomes (quality of life, pain), and radiological outcome were assessed 8 weeks, 6 months, and 1 year after surgery.

Results

Loss of radial length of more than 3 mm was not detected in any group. Volar tilt was better restored by external fixation (7.2°) than by volar plating (0.1°). Wrist function was good in both groups. The external fixator was tolerated very well, and the quality of life assessment revealed comparable results in both groups. Osteoporosis was found in 54 % of patients and had no influence on radiological and functional outcome.

Conclusion

Non-bridging external fixation employing multiplanar K-wires is a suitable treatment option in intra- and extra-articular fractures of the distal radius even in osteoporotic bone.

Level of evidence

Prospective randomized trial, Level I.     

Use of bone graft substitute in the treatment for distal radius fractures in elderly

Introduction

Fractures of the distal radius in elderly patients are often associated with metaphyseal defects that can lead to collapse, malunion and therefore decreased function. An alternative approach to simple reduction is to fill the defects with materials that can provide structural support.

Methods

We used synthetic hydroxyapatite (HA) in unstable fractures of the distal radius in thirty-one elderly patients, of which four patients lost to follow-up, leaving twenty-seven patients for this study. All subjects underwent closed reduction with K-wire fixation and HA augmentation. They were followed up at 8- and 16-week intervals post-operatively to assess the functional outcome using patient-related wrist evaluation [PRWE], clinical outcome and radiological outcome.

Results

At mean 16 weeks, our results show that patients treated with this method showed no metaphyseal defect, no collapse and had satisfactory clinical outcome as assessed by PRWE.

Conclusion

We believe that fixation with hydroxyapatite augmentation for fractures of the distal radius in elderly patients is an attractive therapeutic option. This experience has changed our clinical practice.     

Cement augmentation of lag screws: an investigation on biomechanical advantages

Background

In trauma surgery, lag screws are commonly used. However, in osteoporotic bone, anchorage can be considerably compromised. This study investigates the biomechanical potential of cement augmentation in terms of improved fixation.

Methods

36 Surrogate osteoporotic bone specimens were utilised in three biomechanical experiments, each comparing 6 augmented with 6 non-augmented samples. Standard partially-threaded lag screws (Synthes) were placed following surgical standard. For the augmented groups, 0.4 ml of polymethylmethacrylate was injected into the pre-drilled hole prior to screw placement. Interfragmentary compression was determined using a cannulated ring compression sensor. Maximum torque was recorded with a torque wrench. Compressive relaxation after 24 h, relaxation after loosening and re-tightening the screw as well as maximum compression and torque at failure were measured.

Findings

Mean relaxation was significantly lower for the augmented group (p < 0.01). After 24 h, a remaining fragmental compression of 62 % for the augmented and 52 % for the non-augmented specimens was found. Loosening and re-tightening of the screw did not affect the compressive relaxation when augmentation was applied (p = 0.529), compared to an increased relaxation after re-tightening in the non-augmented group (p = 0.04). The mean maximum compression and torque until failure were significantly higher for the augmented group (p < 0.001).

Interpretation

Cement augmentation of lag screws can improve fixation stability in terms of installing and maintaining interfragmentary compression. Effects of relaxation can be reduced and re-tightening of screws is possible without compromising the fixation. Particularly in reduced bone mass, augmentation of lag screws can markedly increase the security of the technique.     

The use of bone cement in difficult distal radius fractures

Background

The lack of structural support remains a challenge in the treatment of comminuted distal radius fractures. Calcium phosphate and calcium sulfate bone cement has been used in other fracture locations in addition to fixation and has been shown to allow for retention of reduction in difficult cases.

Methods

A case-control retrospective review of 34 consecutive distal radius fractures treated with surgery was performed with the patients classified by Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification. Complications and postoperative radiographs were evaluated.

Results

Cement was used in the most difficult cases. Radial height was retained in both groups. Volar tilt was significantly better in the cement group. There were no significant differences between the case and control groups for any complication. No complications related to the use of the cement were found.

Conclusions

The use of bone cement as an adjunct to fixation of distal radius fractures seems to include minimal risks and may afford a technical advantage in maintaining reduction during surgery for difficult fractures. Since there is an aspect of fracture difficulty that we cannot control for by using radiographic assessment alone, cement may provide an advantage over fixation without cement, despite similar outcomes. Bone cement can be part of the "tool box" for difficult distal radius fractures. Further study is necessary to define the technical advantages and limitations of each particular cement product.     

Palmar multidirectional fixed-angle plate fixation in distal radius fractures: do intraarticular fractures have a worse outcome than extraarticular fractures?

Introduction

The results and complications using a palmar plate system with the possibility of multidirectional fixed-angle screw fixation (Aptus^® Radius 2.5 mm by Medartis^®) for the treatment of unstable distal radius fractures were evaluated in a single cohort study including 62 patients.

Patients

Patients with extra- and intraarticular fractures were evaluated separately. The mean follow-up was 14.7 months. Active wrist motion averaged 60.1° extension, 52.0° flexion, 86.3° pronation, and 84.6° supination. Grip strength averaged 89% of the contralateral wrist.

Results

There was no loss of the initial reduction with bony union in all cases. The mean DASH-score was 12.6 points. Postoperative complications included two extensor pollicis longus tendon ruptures, two median nerve compression syndromes, one complex regional pain syndrome, and one postoperative haematoma. In our series the results of the intraarticular fracture group were similar to the extraarticular fracture group. The complication rate, however, was substantially higher in the intraarticular fracture group.

Conclusion

We conclude that palmar plating with multidirectional fixed-angle screw insertion is an effective and useful treatment option, especially for complex intraarticular distal radius fractures.     

Influence of the screw augmentation technique and a diameter increase on pedicle screw fixation in the osteoporotic spine: pullout versus fatigue testing

Purpose

For posterior spinal stabilization, loosening of pedicle screws at the bone-screw interface is a clinical complication, especially in the osteoporotic population. Axial pullout testing is the standard pre-clinical testing method for new screw designs although it has questioned clinical relevance. The aim of this study was to determine the fixation strength of three current osteoporotic fixation techniques and to investigate whether or not pullout testing results can directly relate to those of the more physiologic fatigue testing.

Methods

Thirty-nine osteoporotic, human lumbar vertebrae were instrumented with pedicle screws according to four treatment groups: (1) screw only (control), (2) prefilled augmentation, (3) screw injected augmentation, and (4) unaugmented screws with an increased diameter. Toggle testing was first performed on one pedicle, using a cranial-caudal sinusoidal, cyclic (1.0 Hz) fatigue loading applied at the screw head. The initial compressive forces ranged from 25 to 75 N. Peak force increased stepwise by 25 N every 250 cycles until a 5.4-mm screw head displacement. The contralateral screw then underwent pure axial pullout (5 mm/min).

Results

When compared to the control group, screw injected augmentation increased fatigue force (27 %, p = 0.045) while prefilled augmentation reduced fatigue force (?7 %, p = 0.73). Both augmentation techniques increased pullout force compared to the control (ps < 0.04). Increasing the screw diameter by 1 mm increased pullout force (24 %, p = 0.19), fatigue force (5 %, p = 0.73), and induced the least stiffness loss (?29 %) from control.

Conclusions

For the osteoporotic spine, screw injected augmentation showed the best biomechanical stability. Although pullout testing was more sensitive, the differences observed were not reflected in the more physiological fatigue testing, thus casting further doubt on the clinical relevance of pullout testing.     

Biomechanical comparison of vertebral augmentation with silicone and PMMA cement and two filling grades

Purpose

Vertebral augmentation with PMMA is a widely applied treatment of vertebral osteoporotic compression fractures. Subsequent fractures are a common complication, possibly due to the relatively high stiffness of PMMA in comparison with bone. Silicone as an augmentation material has biomechanical properties closer to those of bone and might, therefore, be an alternative. The study aimed to investigate the biomechanical differences, especially stiffness, of vertebral bodies with two augmentation materials and two filling grades.

Methods

Forty intact human osteoporotic vertebrae (T10–L5) were studied. Wedge fractures were produced in a standardized manner. For treatment, PMMA and silicone at two filling grades (16 and 35 % vertebral body fill) were assigned to four groups. Each specimen received 5,000 load cycles with a high load range of 20–65 % of fracture force, and stiffness was measured. Additional low-load stiffness measurements (100–500 N) were performed for intact and augmented vertebrae and after cyclic loading.

Results

Low-load stiffness testing after cyclic loading normalized to intact vertebrae showed increased stiffness with 35 and 16 % PMMA (115 and 110 %) and reduced stiffness with 35 and 16 % silicone (87 and 82 %). After cyclic loading (high load range), the stiffness normalized to the untreated vertebrae was 361 and 304 % with 35 and 16 % PMMA, and 243 and 222 % with 35 and 16 % silicone augmentation. For both high and low load ranges, the augmentation material had a significant effect on the stiffness of the augmented vertebra, while the filling grade did not significantly affect stiffness.

Conclusions

This study for the first time directly compared the stiffness of silicone-augmented and PMMA-augmented vertebral bodies. Silicone may be a viable option in the treatment of osteoporotic fractures and it has the biomechanical potential to reduce the risk of secondary fractures.     

Less invasive surgery with wrist arthroscopy for distal radius fracture

Background

We developed a surgical procedure that can facilitate arthroscopic intervention for volar locking plate fixation for distal radius fracture (DRF) with a less invasive technique. This study is to investigate the effectiveness of our original procedure for the treatment of DRF.

Methods

One hundred fifty-five wrists of 153 consecutive patients underwent our original procedure: the plate presetting arthroscopic reduction technique (PART) for DRF. The fractures consisted of 37 extra-articular and 118 intra-articular fractures. The fractures were reduced, anatomical alignment was regained with the aid of an image intensifier, and the volar locking plate was preset. Wrist arthroscopy was then performed and the intra-articular condition assessed. If there were any residual dislocations of the intra-articular fragments, these were reduced arthroscopically, and soft tissue injuries were subsequently treated. The traction was then removed, and the plate was securely fixed. One hundred forty-five patients were followed up from 12 to 48 months. The final outcome was evaluated with the Mayo modified wrist score and Disability of the Arm, Shoulder and Hand questionnaire (DASH). The effectiveness of arthroscopy was also investigated.

Result

On arthroscopic inspection, intra-articular dislocations were found to be residual in 35.2 %, even if reduction seemed to have been achieved when viewed with the image intensifier. Scapholunate interosseous ligament injury was recognized in 28.9 %, and triangular fibrocartilage complex injury was observed in 63.2 %. The final outcome was 112 excellent, 31 good, and 2 fair. The mean DASH score was 4.1.

Conclusion

We developed the PART to simplify the combination of volar locking plating and arthroscopy. This technique was less invasive and effective in the treatment of DRF.     

Cement Augmentation in Sacroiliac Screw Fixation Offers Modest Biomechanical Advantages in a Cadaver Model

Background

Sacroiliac screw fixation in elderly patients with pelvic fractures is prone to failure owing to impaired bone quality. Cement augmentation has been proposed as a possible solution, because in other anatomic areas this has been shown to reduce screw loosening. However, to our knowledge, this has not been evaluated for sacroiliac screws.

Questions/purposes

We investigated the potential biomechanical benefit of cement augmentation of sacroiliac screw fixation in a cadaver model of osteoporotic bone, specifically with respect to screw loosening, construct survival, and fracture-site motion.

Methods

Standardized complete sacral ala fractures with intact posterior ligaments in combination with ipsilateral upper and lower pubic rami fractures were created in osteoporotic cadaver pelves and stabilized by three fixation techniques: sacroiliac (n = 5) with sacroiliac screws in S1 and S2, cemented (n = 5) with addition of cement augmentation, and transsacral (n = 5) with a single transsacral screw in S1. A cyclic loading protocol was applied with torque (1.5 Nm) and increasing axial force (250–750 N). Screw loosening, construct survival, and sacral fracture-site motion were measured by optoelectric motion tracking. A sample-size calculation revealed five samples per group to be required to achieve a power of 0.80 to detect 50% reduction in screw loosening.

Results

Screw motion in relation to the sacrum during loading with 250 N/1.5 Nm was not different among the three groups (sacroiliac: 1.2 mm, range, 0.6–1.9; cemented: 0.7 mm, range, 0.5–1.3; transsacral: 1.1 mm, range, 0.6–2.3) (p = 0.940). Screw subsidence was less in the cemented group (3.0 mm, range, 1.2–3.7) compared with the sacroiliac (5.7 mm, range, 4.7–10.4) or transsacral group (5.6 mm, range, 3.8–10.5) (p = 0.031). There was no difference with the numbers available in the median number of cycles needed until failure; this was 2921 cycles (range, 2586–5450) in the cemented group, 2570 cycles (range, 2500–5107) for the sacroiliac specimens, and 2578 cycles (range, 2540–2623) in the transsacral group (p = 0.153). The cemented group absorbed more energy before failure (8.2 × 10⁵ N*cycles; range, 6.6 × 10⁵–22.6 × 10⁵) compared with the transsacral group (6.5 × 10⁵ N*cycles; range, 6.4 × 10⁵–6.7 × 10⁵) (p = 0.016). There was no difference with the numbers available in terms of fracture site motion (sacroiliac: 2.9 mm, range, 0.7–5.4; cemented: 1.2 mm, range, 0.6–1.9; transsacral: 2.1 mm, range, 1.2–4.8). Probability values for all between-group comparisons were greater than 0.05.

Conclusions

The addition of cement to standard sacroiliac screw fixation seemed to change the mode and dynamics of failure in this cadaveric mechanical model. Although no advantages to cement were observed in terms of screw motion or cycles to failure among the different constructs, a cemented, two-screw sacroiliac screw construct resulted in less screw subsidence and greater energy absorbed to failure than an uncemented single transsacral screw.

Clinical Relevance

In osteoporotic bone, the addition of cement to sacroiliac screw fixation might improve screw anchorage. However, larger mechanical studies using these findings as pilot data should be performed before applying these preliminary findings clinically.