Locking plate technology and its applications in upper extremity fracture care

Delayed Union and Nonunion: Current Concepts, Prevention, and Correction: A Review

Surgical management of fractures has advanced with the incorporation of advanced technology, surgical techniques, and regenerative therapies, but delayed bone healing remains a clinical challenge and the prevalence of long bone nonunion ranges from 10 to 15% of surgically managed fractures. Delayed bone healing arises from a combination of mechanical, biological, and systemic factors acting on the site of tissue remodeling, and careful consideration of each case's injury-related, patient-dependent, surgical, and mechanical risk factors is key to successful bone union. In this review, we describe the biology and biomechanics of delayed bone healing, outline the known risk factors for nonunion development, and introduce modern preventative and corrective therapies targeting fracture nonunion.

The Pitfalls of Difficult Distal Radius Fractures and Provisional Reduction

Distal radius fractures are some of the most common injuries encountered in orthopedics and require careful consideration when determining the appropriate treatment options. These fractures can be difficult injuries to treat surgically based on a large variability of fracture patterns, bone quality, and anatomy. It is important to understand the potential pitfalls associated with the treatment of difficult distal radius fractures to prevent avoidable complications. Some of these pitfalls include but are not limited to appropriate surgical exposure and soft tissue handling, provisional reduction, fixation type, and augmentation of fracture fixation.

Changes in tibial cortical dimensions and density associated with long-term locking plate fixation in goats

PURPOSE

Cortical porosis, secondary to either vascular injury or stress-shielding, is a comorbidity of fracture fixation using compression bone plating. Locking plate constructs have unique mechanics of load transmission and lack of reliance on contact pressures for fixation stability, so secondary cortical porosis adjacent to the plate has not been widely investigated. Therefore, this study aimed to assess the effects of long-term locking plate fixation on cortical dimensions and density in a caprine tibial segmental ostectomy model.

METHODS

Data was acquired from a population of goats enrolled in ongoing orthopedic research which utilized locking plate fixation of 2 cm tibial diaphyseal segmental defects to evaluate bone healing over periods of 3, 6, 9, and 12 months. Quantitative data included tibial cortical width measurements and three-dimensionally reconstructed slab density measurements, both assessed using computed tomographic examinations performed at the time of plate removal. Additional surgical and demographic variables were analyzed for effect on cortical widths and density, and all cis-cortex measurements were compared to both the trans-cortex and to the contralateral limbs.

RESULTS

The tibial cis-cortex was significantly wider and more irregular than the trans-cortex at the same level. This width asymmetry differed in both magnitude and direction from the contralateral limb. The bone underlying the plate was significantly less dense than the trans-cortex, and this cortical density difference was significantly greater than that of the contralateral limb. These cortical changes were independent of both duration of fixation and degree of ostectomy bone healing.

CONCLUSIONS

This study provides evidence that cortical bone loss consistent with cortical porosity is a comorbidity of locking plate fixation in a caprine tibial ostectomy model. Further research is necessary to identify risk factors for locking-plate-associated bone loss and to inform clinical decisions in cases necessitating long-term locking plate fixation.

Biologic plating of unstable distal radial fractures

Background

Volar locking plating through the flexor carpi radialis is a well-established technique for treating unstable distal radial fractures, with few reported complications. In certain circumstances, including metaphyseal comminuted fractures, bridge plating through a pronator quadratus (PQ)-sparing approach may be required to preserve the soft tissue envelope. This study describes our prospective experience with bridge plating through indirect reduction.

Methods

Thirty-three wrists (four 23A2, six 23A3, 15 23C1, and eight 23C2) underwent bridge plating through a PQ-sparing approach with indirect reduction from June 2006 to December 2010. Mean patient age was 56.8 years (range, 25–83 years), and the mean follow-up period was 47.5 months (range, 36–84 months). Changes in radiologic parameters (volar tilt, radial inclination, radial length, and ulnar variance) were analyzed, and functional results at final follow-up were evaluated by measuring the Modified Mayo Wrist Score (MMWS) and Modified Gartland-Werley Score (MGWS).

Results

All wrists achieved bone healing without significant complications after a single operation. At final follow-up, radial length was restored from an average of 3.7 mm to 11.0 mm, as were radial inclination, from 16.4° to 22.5°, and volar tilt, from − 9.1° to 5.5°. However, radial length was overcorrected in three wrists, and two experienced residual dorsal tilt. Excellent and good results on the MGWS were achieved in 30 wrists (90.9%). The average MMWS outcome was 92.6 (range, 75–100).

Conclusion

Our experience with bridge plating was similar to that previously reported in the earlier publications. Compared with the conventional technique, bridge plating through a PQ-sparing approach may help in managing metaphyseal comminuted fractures of both cortices with a reduced radio-ulnar index.

Stifle arthrodesis using a locking plate system in six dogs

Objectives: To describe the use of the Fixin locking plate system for stifle arthrodesis in dogs and to retrospectively report the clinical and radiographic outcomes in six cases.[uni2028]

Materials and methods: Medical records of dogs that had arthrodesis with the Fixin locking plate system were reviewed. For each patient, data pertaining to signalment and implant used were recorded. Plate series and thickness, number of screws placed, number of cortices engaged, and screw diameters were also recorded. The outcome was determined from clinical and radiographic followups. Radiographic outcomes assessed included the measurement of the postoperative femoral-tibial angle in the sagittal plane.

Results: Six dogs met the inclusion criteria for the study. Mean body weight was 13 kg (range: 3 - 34 kg). Radiographic follow-up (mean: 32 weeks, range: 3 - 52 weeks) was available for all dogs. In one case, an intra-operative complication occurred. In another case, a tibial fracture occurred 20 days after surgery. All arthrodeses healed and no implant complication was detected although all cases had mechanical lameness.

Clinical significance: Stifle arthrodesis can be performed successfully using a Fixin locking plate system.

Experiences using the Fixin locking plate system for the stabilization of appendicular fractures in dogs

Objectives: To retrospectively evaluate the stabilization of appendicular fractures in dogs using the Fixin locking plate system.

Materials and methods: Medical records and radiographs of dogs with fractures stabilized with the Fixin system in the period from May 2005 to September 2010 were reviewed. For each patient, data pertaining to signalment, the nature of the fracture, implants used, and evidence of fracture healing were recorded. The outcome and complications were determined from clinical and radiographic follow-up examinations. Limb function was evaluated between 40 days and 90 days postoperatively. Owners of pets with complications were contacted by phone for long-term follow-up.

Results: Eighty-two fractures in seventy-five dogs met the inclusion criteria for the study. Radiographic re-examinations were carried out between eight days to two years (median 60 days) following surgery. Seventy-three out of 82 fractures (89%) reached union without complications. Major complications were seen in six dogs (7%). Limb function was graded as ‘normal’ in 73/75 (97%) dogs and ‘mild lameness’ in 2/75 (3%) cases.

Clinical significance: Despite a modest complication rate, the Fixin locking bone plating system appears to be an acceptable choice of implant for the stabilization of appendicular fractures in dogs.

Clinical evaluation of a mini locking plate system for fracture repair of the radius and ulna in miniature breed dogs

Objectives: To retrospectively evaluate the effectiveness of a novel 1.2 mm mini locking plate system in treating fractures of the radius and ulna in miniature breed dogs.

Methods: Medical records and radiographs of miniature breed dogs with fractures treated with a 1.2 mm mini locking plate system were reviewed. The inclusion criteria were: body weight of 2.5 kg or less, trans-verse or short oblique fracture of the radius and ulna, and treatment with a mini locking plate system as the sole method of fixation. For each patient, data including signalment, time to radiographic union, use of bone graft or other agents, and previous repair attempts were recorded. The outcome and complications were determined from clinical and radiographic follow-up examinations.

Results: Fourteen cases with a mean radial width of 4.5 mm (± 0.8 mm) were included into this study. The fractures healed without failure of fixation in all cases. Mean time to adequate radiographic union was 8.4 weeks (± 2.6 weeks). Major complications were not seen in any of the cases, and minor complications occurred in three of the cases. Limb function was graded as ‘normal’ in 10 cases and ‘occasional lameness’ in four cases.

Clinical significance: The mini locking system evaluated in this study was an effective treatment method for radial and ulnar fractures in miniature breed dogs with a radial width smaller than 5.5 mm.

Supplementary Material to this article is available online at http://dx.doi.org/10.3415/VCOT-16-01-0014.

Treatment of pes varus using locking plate fixation in seven Dachshund dogs

Objectives: To describe the surgical treatment of pes varus in Dachshund dogs by medial opening wedge osteotomy of the distal tibia stabilized with a locking plate system and to retrospectively report the clinical and radiographic outcomes.

Materials and methods: Lameness in nine limbs of seven Dachshund dogs with pes varus deformity was treated with corrective osteotomy at or near the centre of rotation of angulation as defined by the intersection of the proximal and distal mechanical axes determined on caudo-cranial radiographs. Outcomes evaluated included comparison of preand postoperative radiographic measurements of frontal angulation and lameness assessment.

Results: Lameness resolved in eight limbs and improved in one limb. All osteotomies healed and no implant complications were detected. Mean preoperative radiographic measurements were: mechanical medial proximal tibial angle (mMPTA) = 91.1° (range 87.6°-95°), mechanical medial distal tibial angle (mMDTA) = 62.1° (range 51.9°-69.6°). Mean postoperative measurements were: mMPTA 92.4° (range 78°-97.5°), mMDTA 81.8° (range 76°-87°). Measurable undercorrection was common, though seldom visually or functionally evident.

Clinical significance: Pes varus deformity in Dachshunds can be treated by medial opening wedge osteotomy of the distal tibia stabilized with a locking plate system. Care to preserve the lateral cortex of the osteotomy may help avoid under-correction.

Contralateral bone widening and transfer for limb sparing in a cat

OBJECTIVE

To report on a novel surgical procedure to treat a long segmental tibial defect in a five-year-old 5 kg spayed female Main Coon cat using transverse distraction osteogenesis in the contralateral tibia to create a free autograft.

METHODS

A long free bone segment was created from the cranial half of the normal tibia. A circular external fixator was constructed to give the segment 7 mm of cranial distraction. After 42 days the widened section of tibial bone was removed and transferred to the defect in the contralateral tibia. Locking plates were used to stabilize the graft and to protect the donor tibial sites.

RESULTS

By 27 months, both tibias were healed, all implants had been removed, function was excellent, and the overall limb length was 90% of the normal side.

CLINICAL RELEVANCE

Compared with longitudinal distraction osteogenesis in long bone defects, transverse distraction of a normal bone requires a significantly shorter distraction distance to produce a similar amount of bone. Thus, distraction time is reduced, with less likelihood of significant soft tissue damage. New bone may be more reliably regenerated in a normal limb due to better tissue health, and native bone may be more readily incorporated than allografts in compromised sites. Disadvantages include the increased morbidity, as well as the risk and expense associated with involvement of a normal limb.

Rapid prototyping to design a customized locking plate for pancarpal arthrodesis in a giant breed dog

This report describes the treatment of traumatic carpal hyperextension in a giant breed dog by pancarpal arthrodesis using a custom-made Fixin locking plate, created with the aid of a three-dimensional plastic model of the bones of the antebrachium produced by rapid prototyping technology. A three-year-old 104 kg male Mastiff dog was admitted for treatment of carpal hyperextension injury. After diagnosis of carpal instability, surgery was recommended. Computed tomography images were used to create a life-size three-dimensional plastic model of the forelimb. The model was used as the basis for constructing a customized 12-hole Fixin locking plate. The plate was used to attain successful pancarpal arthrodesis in the animal. Radiographic examination after 74 and 140 days revealed signs of osseous union of the arthrodesis. Further clinical and radiographic follow-up examination three years later did not reveal any changes in implant position or complications.

Surgical treatment of distal radial fractures with a volar locking plate versus conventional percutaneous methods: a randomized controlled trial

BACKGROUND

The aim of this study was to compare the outcomes of displaced distal radial fractures treated with a volar locking plate with the results of such fractures treated with a conventional method of closed reduction and percutaneous wire fixation with supplemental bridging external fixation when required. Our aim was to ascertain whether the use of a volar locking plate improves functional outcomes.

METHODS

A single-center, pragmatic, randomized controlled trial was conducted in a tertiary care institution. One hundred and thirty patients (eighteen to seventy-three years of age) who had a displaced distal radial fracture were randomized to treatment with either a volar locking plate (n = 66) or a conventional percutaneous fixation method (n = 64). Outcome assessments were conducted at six weeks, twelve weeks, and one year. Outcomes were measured on the basis of scores on the Patient Evaluation Measure (PEM) and QuickDASH questionnaire (a shortened version of the Disabilities of the Arm, Shoulder and Hand, or DASH, Outcome Measure), EuroQol-5D (EQ-5D) scores, wrist range of motion, grip strength, and radiographic parameters.

RESULTS

The rate of follow-up at one year was 95%. Patients in the volar locking-plate group had significantly better PEM and QuickDASH scores and range of motion at six weeks compared with patients in the conventional-treatment group, but there were no significant differences between the two groups at twelve weeks or one year. Grip strength was better in the plate group at all time points. The volar locking plate was better at restoring palmar tilt and radial height. Significantly more patients in the plate group were driving at the end of six weeks, but this did not translate to a significant difference between groups in terms of those returning to work by that time.

CONCLUSIONS

Use of a volar locking plate resulted in a faster early recovery of function compared with use of conventional methods. However, no functional advantage was demonstrated at or beyond twelve weeks. Use of the volar locking plate resulted in better anatomical reduction and grip strength, but there was no significant difference in function between the groups at twelve weeks or one year. The earlier recovery of function may be of advantage to some patients.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Outcomes of pin and plaster versus locking plate in distal radius intraarticular fractures

Background

Distal radius fractures are among the most prevalent fractures predictive of probable occurrence of other osteoporotic fractures. They are treated via a variety of methods, but the best treatment has not been defined yet.

Objectives

This study was performed to compare the results of open reduction and internal fixation with locking plates versus the pin and plaster method.

Materials and Methods

In this prospective study, 114 patients aged 40 to 60 years with Fernandez type III fracture referring to Imam-Reza and Mehr hospitals of Mashhad from 2009 to 2011, were selected randomly; after obtaining informed consent, they were treated with pin and plaster fixation (n = 57) or internal fixation with the volar locking plate (n = 57). They were compared at the one year follow up. Demographic features and standard radiographic indices were recorded and MAYO, DASH and SF - 36 tests were performed. Data was analyzed by SPSS software version 13, with descriptive indices, Mann-Whitney and Chi-square tests.

Results

SF-36 test demonstrated a better general health (P < 0.001), mental health (P = 0.006), physical functioning (P < 0.001), social functioning (P < 0.001) and energy/fatigue (P < 0.001) in LCP group. However, pain (P = 0.647) was not significantly different between the groups. Physical limitation (P < 0.001) and emotional limitation (P < 0.001) were greater in the pin and plaster group. Also, in the LCP group mean MAYO score (P < 0.001) was more than pin and plaster group. Mean DASH score was not different between the groups (P = 0.218). The rate of acceptable results of radiographic indices (P < 0.001), grip strength (P < 0.001) and range of motion in supination-pronation (P < 0.001) in LCP method were better than the pin and plaster method.

Conclusions

In treatment of intra-articular distal radius fractures in middle-aged patients internal fixation with locking plates may be prefered to pin and plaster as the treatment of choice.

Can locking screws allow smaller, low-profile plates to achieve comparable stability to larger, standard plates?

OBJECTIVE

The open reduction and internal fixation of radial shaft fractures and osteotomies with standard 3.5-mm plates can be complicated by tendon irritation, hardware prominence, and fracture through the screw holes. With the advent of locking plate technology, implant companies and some surgeons have recommended expanding the indications for these devices; for example, using smaller, low-profile locking plates to suffice where a standard, larger plate would traditionally be used. We analyzed whether there is merit to this strategy. We hypothesized that, in an established cadaveric fracture fixation model, a smaller, low-profile plate with multiple locking screws could maintain adequate fixation stiffness with the potential to minimize hardware-related complications.

METHODS

Seven matched pairs of fresh-frozen cadaver radii were used. A 5-mm osteotomy gap was created at the midpoint of each specimen and the simulated fracture in one radius from each pair was fixed with a 3.5-mm plate and six nonlocking, standard screws. The contralateral radius was fixed using an equivalent-length 2.7-mm plate with eight locking screws. The radii were subjected to controlled bending and torsional loads and the bending and torsional stiffnesses were documented. Cyclic dorsal-to-volar bending was then applied and resistance to fatigue bending assessed.

RESULTS

The 2.7-mm locking plate was approximately one third as stiff as the 3.5-mm nonlocking plate (P < 0.02). Under physiological loading conditions, the 3.5-mm plate was superior to the 2.7-mm plate with respect to bending stiffness in all four directions, torsional stiffness in both directions, osteotomy gapping, and osteotomy angulation (P < 0.02 for all tests). The performance gap did not narrow with cyclic testing.

CONCLUSIONS

The theoretical structural benefit from the locking screws did not make up for the smaller size of the 2.7-mm plate. This held true in all bending planes, torsion, and cyclic loading, and outweighed any biologic differences between the specimens, including the presence or absence of osteoporosis. This is the first study to rigorously compare these two constructs and we conclude that the mechanical properties of the standard 3.5-mm plate are superior to the locking 2.7-mm plate in all regimes tested.

Comparison of olecranon plate fixation in osteoporotic bone: do current technologies and designs make a difference?

OBJECTIVES

The purpose of this study is to determine if recent innovations in olecranon plates have any advantages in stabilizing osteoporotic olecranon fractures.

METHODS

Five olecranon plates (Acumed, Synthes-SS, Synthes-Ti, US Implants/ITS, and Zimmer) were implanted to stabilize a simulated comminuted fracture pattern in 30 osteoporotic cadaveric elbows. Specimens were randomized by bone mineral density per dual-energy x-ray absorptiometry scan. Three-dimensional displacement analysis was conducted to assess fragment motion through physiological cyclic arcs of motion and failure loading, which was statistically compared using one-way analysis of variance and Tukey honestly significant difference post hoc comparisons with a critical significance level of α = 0.05.

RESULTS

Bone mineral density ranged from 0.546 g/cm to 0.878 g/cm with an average of 0.666 g/cm. All implants limited displacement of the fragments to less than 3 mm until sudden, catastrophic failure as the bone of the proximal fragment pulled away from the implant. The maximum load sustained by all osteoporotic specimens ranged from 1.6 kg to 6.6 kg with an average of 4.4 kg. There was no statistical difference between the groups in terms of cycles survived and maximum loads sustained.

CONCLUSIONS

Cyclic physiological loading of osteoporotic olecranon fracture fixation resulted in sudden, catastrophic failure of the bone-implant interface rather than in gradual implant loosening. Recent plate innovations such as locking plates and different screw designs and positions appear to offer no advantages in stabilizing osteoporotic olecranon fractures. Surgeons may be reassured that the current olecranon plates will probably adequately stabilize osteoporotic fractures for early motion in the early postoperative period, but not for heavy activities such as those that involve over 4 kg of resistance.

Internal fixation of fractures of both bones forearm: Comparison of locked compression and limited contact dynamic compression plate

BACKGROUND

The locking compression plate (LCP) with combination holes is a newer device in fracture fixation. We undertook a study comparing the LCP with limited contact dynamic compression plate (LC-DCP) in the treatment of diaphyseal fractures of both bones of the forearm.

MATERIALS AND METHODS

This is a prospective comparative study, 36 patients (18 in each group) with fractures of both the forearm bones (72 fractures) were treated with one of the two devices. The average age of the patients was 30.5 years (range 16-60 years) with mean followup of 2.1 years (range 1.5-2.8 years). The patients were assessed for fracture union and function and complications and by Disabilities of the Arm, Shoulder and Hand (DASH) score for patient related outcome at the latest followup.

RESULTS

There was no significant difference in two groups with respect to the range of movements or grip strength. One case had delayed union (LC-DCP group) and another had synostosis (LCP group). Plate removal was done in four cases within the study period with no refracture till the presentation of this report.

CONCLUSION

LC plating is an effective treatment option for fractures of both bones of forearm. The present study could not prove its superiority over LC-DCP.

Problems of bridging plate fixation for the treatment of forearm shaft fractures with the locking compression plate

INTRODUCTION

Treatment of diaphyseal forearm fractures by open reduction and internal plate fixation is a well-accepted strategy. In a variety of fracture localizations, the use of bridging plate fixation with locking compression plates (LCP) has been shown to improve biomechanical and biological characteristics. Only very limited clinical data are available on bridging plate fixation using LCPs for the treatment of diaphyseal forearm fractures. The aims of this study were to assess both clinical outcomes of LCP fracture treatments, and the implant-specific advantages and disadvantages.

METHOD

The study consisted of 53 patients. All relevant data were extracted from the medical reports and radiographs. Of the 53 patients, 39 completed the disabilities of the arm, shoulder and hand (DASH) questionnaire and 35 patients were available for clinical examination. The mean time of follow-up was 23.3 months.

RESULTS

Thirty-nine fractures of the radius and 45 fractures of the ulna were treated with 3.5 mm LCPs. Due to a fracture non-union, four patients underwent a second operation. In 13 patients, hardware had already been removed at the time of follow-up. Complete documentation of the removal operation was available for ten patients; in seven of these, procedures difficulties occurred. Mean ranges of motion were 138°, 141° and 162° for elbow flexion-extension, wrist flexion-extension and pronation-supination, respectively. The mean DASH score was calculated at 14.9.

CONCLUSION

In conclusion, our data show that clinical and functional outcomes of LCP plating of diaphyseal forearm fractures are comparable to the use of conventional implants. However, implant-specific problems during hardware removal must be considered.

Minimising the risk of extensor pollicis longus rupture following volar plate fixation of distal radius fractures: a cadaveric study

INTRODUCTION

Rupture of extensor pollicis longus (EPL) tendon is a recognised complication following volar plate fixation of distal radius fractures, usually from attrition caused by prominent screws. We sought to identify the screw holes in some of the most commonly used plates which may precipitate tendon injury.

SUBJECTS AND METHODS

Three fixed-angle volar locking plates were sequentially positioned into 18 cadaveric arms. A wire was passed through each of the holes in the plates using a locking guide and the dorsal relationships noted.

RESULTS

Each plate had specific 'high-risk' holes which directed the wire towards the EPL groove. The central screw holes appeared mostly implicated in EPL injury.

CONCLUSIONS

Awareness of 'high-risk' holes and appropriate minor alterations in surgical technique may consequently decrease the incidence of EPL irritation and rupture.

Biomechanics of humerus fracture fixation by locking, cortical, and hybrid plating systems in a cadaver model

The goal of this study was to discover how locking or cortical screws or a hybrid of both would perform in stabilizing a simulated humerus fracture. We simulated stripping of screw threads or poor bone quality by overdrilling the screw hole, and also studied a control group with no overdrilling. A total of 38 fresh frozen cadaver humeri were divided into 2 groups: 16 undergoing overdrilling with a drill bit 0.3 mm less than the diameter of the screw and 22 undergoing no overdrilling. A 4-point bending test followed torsional fatigue of 1000 cycles with an amplitude of +/-10 degrees. The post-fatigued samples were retested in the same way after tightening the loose screws if necessary. Finally, each fatigued specimen was tested for failure in torsion at 0.5 Hz by applying a maximum rotational displacement of 60 degrees .The bending stiffness values (Nm/mm) of cortical and locking screws, with the exception of the hybrid system, were significantly higher for the overdrilled group than the non-overdrilled (cortical, 6.9 vs 5.6; locking, 9.1 vs 6.3; hybrid, 8.4 vs 6.8). Fatigue had no effect on the bending stiffness of all the screw/plate systems (cortical, 6.9 vs 7.4; locking, 9.1 vs 8.8; hybrid, 8.5 vs 8.1). The overdrilling had no effect on the failure loads and displacements for all the screws except cortical screws, where the failure displacement was significantly higher for the overdrilling group. The torsional stiffness retentions after 1000 cycles were significantly different for overdrilled specimens in the cortical screws group only.Overdrilling had a minimal effect on bending and torsional properties. The results of the locking and hybrid were close, and the cortical screw had only slightly lower bending stiffness.

Biomechanical comparison of double-row locking plates versus single- and double-row non-locking plates in a comminuted metacarpal fracture model

PURPOSE

Open or unstable metacarpal fractures frequently require open reduction and internal fixation. Locking plate technology has improved fixation of unstable fractures in certain settings. In this study, we hypothesized that there would be a difference in strength of fixation using double-row locking plates compared with single- and double-row non-locking plates in comminuted metacarpal fractures.

METHODS

We tested our hypothesis in a gap metacarpal fracture model simulating comminution using fourth-generation, biomechanical testing-grade composite sawbones. The metacarpals were divided into 6 groups of 15 bones each. Groups 1 and 4 were plated with a standard 6-hole, 2.3-mm plate in AO fashion. Groups 2 and 5 were plated with a 6-hole double-row 3-dimensional non-locking plate with bicortical screws aimed for convergence. Groups 3 and 6 were plated with a 6-hole double-row 3-dimensional locking plate with unicortical screws. The plated metacarpals were then tested to failure against cantilever apex dorsal bending (groups 1-3) and torsion (groups 4-6).

RESULTS

The loads to failure in groups 1 to 3 were 198 +/- 18, 223 +/- 29, and 203 +/- 19 N, respectively. The torques to failure in groups 4 to 6 were 2,033 +/- 155, 3,190 +/- 235, and 3,161 +/- 268 N mm, respectively. Group 2 had the highest load to failure, whereas groups 5 and 6 shared the highest torques to failure (p < .05). Locking and non-locking double-row plates had equivalent bending and torsional stiffness, significantly higher than observed for the single-row non-locking plate. No other statistical differences were noted between groups.

CONCLUSIONS

When subjected to the physiologically relevant forces of apex dorsal bending and torsion in a comminuted metacarpal fracture model, double-row 3-dimensional non-locking plates provided superior stability in bending and equivalent stability in torsion compared with double-row 3-dimensional locking plates, whereas single-row non-locking plates provided the least stability.

Use of a "hybrid" locking plate for complex metaphyseal fractures and nonunions about the humerus

PURPOSE

To review one surgeon's experience with a novel type of "hybrid" locking plate (which has both 3.5mm and 4.5mm locking holes) for difficult fractures of the meta-diaphyseal humeral shaft.

METHODS

Over a 2-year period, 24 patients who presented with a metaphyseal humeral fracture or nonunion (proximal or distal) were treated surgically by a single surgeon. A "hybrid" locking plate containing 3.5mm locking holes on one end and 4.5mm locking holes on the other end (Metaphyseal plate, Synthes, Paoli, Pa) was used in all patients. The selection of this implant was based on fracture location and bone quality. Fractures were operated on through an anterolateral or direct posterior approach. All fractures were secured with a minimum of three 4.5mm screws on one side of the fracture and three 3.5mm screws on the other side. All patients were treated with a similar post-operative protocol for early range of shoulder and elbow motion.

RESULTS

Three patients were lost to follow-up. The cohort consisted of 15 women and 6 men with a mean age of 49 years (range 18-78). There were 14 acute fractures and 7 nonunions. Twelve fractures involved the distal metaphyseal segment and 9 involved the proximal metaphyseal segment. Twenty-two patients completed a minimum 6-month clinical and radiographic follow-up and form the basis for this report. All 21 patients healed their fractures or nonunions at a mean of 4.5 months. There were no infections or hardware failures. In every case the "hybrid" nature of the plate design was felt to be advantageous.

CONCLUSION

This "second generation" metaphyseal locking plate, which affords the surgeon the ability to place a greater number of smaller calibre screws within a short bone segment, while using traditional large fragment screw fixation in the longer segment, is clearly an improvement in plate design. Meta-diaphyseal upper extremity long bones may serve as the most ideal location for this implant.

A revolution in the management of fractures of the distal radius?

The recent development of locking-plate technology has led to a potential revolution in the management of fractures of the distal radius. This review examines the evidence for pursuing anatomical restoration of the distal radius and the possible advantages and pitfalls of using volar locking plates to achieve this goal. The available evidence for adopting volar locking plates is presented and a number of important and, as yet unanswered, questions are highlighted.