The stability of internal fixation in the proximal phalanx

Outcomes After Surgically Managed Oblique Extra-Articular Proximal Phalanx Fractures: A Comparison of Closed-Reduction Percutaneous Pinning and Open-Reduction Internal Fixation With Lag Screws

BACKGROUND

Long oblique extra-articular proximal phalanx fractures are common orthopedic injuries. When unstable and without substantial comminution, treatment options include closed-reduction percutaneous pinning (CRPP) and open-reduction internal fixation using lag screws (ORIF-screws). The aims of this study are primarily to compare the functional outcomes and complication rates between these techniques and secondarily to assess potential factors affecting outcomes after surgery.

METHODS

All patients with long oblique extra-articular proximal phalanx fractures treated surgically within a single orthopedic institution from 2010 to 2017 were identified. Outcome measures and complications were assessed at the final follow-up.

RESULTS

Sixty patients were included in the study with a mean time to the final follow-up of 41 weeks (range: 12-164 weeks). Thirty-four patients (57%) were treated with CRPP and 26 patients (43%) with ORIF-screws. The mean Disabilities of the Arm, Shoulder, and Hand score across both fixation types was 8 (range: 0-43) and did not differ significantly between the 2 groups. Mean proximal interphalangeal extension at the final follow-up was 9° short of full extension after CRPP and 13° short of full extension after ORIF-screws. The rates of flexion contracture and extensor lag were 15% and 41% in the CRPP group compared with 12% and 68% in the ORIF-screws group. Reoperation rates and complication rates did not differ significantly between fixation strategies.

CONCLUSIONS

Acceptable outcomes can be achieved after surgical fixation of long oblique extra-articular proximal phalanx fractures using both CRPP and ORIF-screws. Extensor lag may be more common after ORIF-screws.

Comparison of Lag Versus Nonlag Screw Fixation for Long Oblique Proximal Phalanx Fractures: A Biomechanical Study

PURPOSE

To compare lag versus nonlag screw fixation for long oblique proximal phalanx (P1) fractures in a cadaveric model of finger motion via the flexor and extensor tendons.

METHODS

We simulated long oblique P1 fractures with a 45° oblique cut in the index, middle, and ring fingers of 4 matched pairs of cadaveric hands for a total of 24 simulated fractures. Fractures were stabilized using 1 of 3 techniques: two 1.5-mm fully threaded bicortical screws using a lag technique, two 1.5-mm fully threaded bicortical nonlag screws, or 2 crossed 1.14-mm K-wires as a separate control. The fixation method was randomized for each of the 3 fractures per matched-pair hand, with each fixation being used in each hand and 8 total P1 fractures per fixation group. Hands were mounted to a custom frame where a computer-controlled, motor-driven, linear actuator powered movement of the flexor and extensor tendons. All fingers underwent 2,000 full flexion and extension cycles. Maximum interfragmentary displacement was continuously measured using a differential variable reluctance transducer. Our primary outcome was the difference in the mean P1 fragment displacement between lag and nonlag screw fixation at 2,000 cycles.

RESULTS

The observed differences in mean displacement between lag and nonlag screw fixation were not statistically significant throughout all time points. A two one-sided test procedure for paired samples confirmed statistical equivalence in the fragment displacement between these fixation methods at all time points, including the primary end point of 2,000 cycles.

CONCLUSIONS

Nonlag screws provided equivalent biomechanical stability to lag screws for simulated long oblique P1 fractures during cyclic testing in this cadaveric model.

CLINICAL RELEVANCE

Fixation of long oblique P1 fractures with nonlag screws has the potential to simplify treatment without sacrificing fracture stability during immediate postoperative range of motion.

Recognizing and managing upper extremity compartment syndrome

Compartment syndrome is an acute limb-threatening condition typically treated with emergency fasciotomy. Although limbs often are saved, ischemia can cause irreversible neurologic damage to the extremity. Patients with upper extremity compartment syndrome may lose fine motor function, which can result in long-term impairment of perceived quality of life. This article reviews the anatomy, physiology, presentation, diagnosis, and treatment of upper extremity compartment syndrome, including rehabilitation, which can reduce complications that occur even in patients who were promptly and properly treated.

Management of metacarpal fractures

The metacarpal fractures are common fractures which are treated by orthopaedic surgeons, plastic surgeons and hand surgeons equally. These are seen in young adults who have active life style. These have a major impact in life style of the patients if these are not treated adequately. The management of the fractures vary among surgeons to surgeons; two surgeons in the same centre can have a different treatment plan for a fracture. There are no standard guidelines for the treatment and it ranges from conservative management, Kirschner's wire (K-wires), plates and screws. This review article is about the management of metacarpal fractures where the commonly done procedures are reviewed.

Proximal Phalanx Fracture Management

BACKGROUND

The goal of proximal phalangeal fracture management is to allow for fracture healing to occur in acceptable alignment while maintaining gliding motion of the extensor and flexor tendons.

METHODS

We reviewed the most current literature on various treatment methods of proximal phalanx fractures, focusing on the indications and outcomes of nonoperative as well as operative interventions.

RESULTS

Stable fractures can be successfully treated nonoperatively, whereas unstable injuries benefit from surgery. Regardless of the surgical intervention employed, the overriding goal is to restore anatomy and impart enough stability to allow for early motion. The surgical dissection contributes to soft tissue scarring and should be minimized.

CONCLUSIONS

Clinical success is achieved when acceptable fracture alignment and stability occur in the setting of unobstructed tendon gliding and early active range of motion.

Skeletal Fixation in a Mutilated Hand

Hand fracture fixation in mutilating injuries is characterized by multiple challenges due to possible skeletal disorganization and concomitant severe injury of soft tissue structures. The effects of skeletal disruption are best analyzed as divided into specific locales in the hand: radial, ulnar, proximal, and distal. Functional consequences of injuries in each of these regions are discussed. Although a variety of implants are now in vogue, K-wire fixation has stood the test of time and is especially useful in multiple fracture situations. Segmental bone loss is quite common in such injuries, which can be safely reconstructed in a staged manner.

Treatment of Rolando Fractures by Open Reduction and Internal Fixation using Mini T-Plate and Screws

INTRODUCTION

Rolando fractures being intra-articular fractures of the most mobile joint of the thumb, assume significance because any residual incongruity of the articular surface may result in loss of motion as well as secondary osteoarthritis and hence serious disability. This fracture continues to pose difficulties to the treating surgeons and although several treatment options have been described for these fractures, there are no definite guidelines.

METHODS

The present study describes the results of open reduction and internal fixation of nine Rolando fractures with large and single fragments, using mini T-plate and screws.

RESULTS

At 3-year follow-up all the fractures had united, functional results were excellent or good in most cases, and all the patients had returned to previous activities. Significant complications such as deep infection and loss of reduction were not encountered in any patient.

CONCLUSION

Open reduction and internal fixation with mini T-plates in properly selected cases of Rolando fracture with large and single palmar and dorsal articular fragments offers several advantages such as allowing direct visualization of the joint, removal of interposed soft tissues, and exact anatomical restoration of the articular surface. The fixation in most cases is rigid enough to allow early mobilization without loss of reduction. Thus, complications such as stiffness as well as future arthrosis may be minimized. However, the technique is demanding and needs high degree of precision. The possibility of implant removal should be discussed beforehand with the patient.

Angular stable lateral plating is a valid alternative to conventional plate fixation in the proximal phalanx. A biomechanical study

BACKGROUND

Dorsal plating is commonly used in proximal phalanx fractures but it bears the risk of interfering with the extensor apparatus. In this study, dorsal and lateral plating fixation methods are compared to assess biomechanical differences using conventional 1.5mm non-locking plates and novel 1.3mm lateral locking plates.

METHODS

Twenty-four fresh frozen human cadaveric proximal phalanges were equally divided into four groups. An osteotomy was set at the proximal metaphyseal-diaphyseal junction and fixed with either dorsal (group A) or lateral (group B) plating using a 1.5mm non-locking plate, or lateral plating with a novel 1.3mm locking plate with bicortical (group C) or unicortical (group D) screws. The specimens were loaded in axial, dorsovolar and mediolateral direction to assess fixation stiffness followed by a cyclic destructive test in dorsovolar loading direction.

FINDINGS

Axial stiffness was highest in group D (mean 321.02, SEM 21.47N/mm) with a significant difference between groups D and B (P=0.033). Locking plates (groups C and D) were stiffer than non-locking plates under mediolateral loading (P=0.007), no significant differences were noted under dorsovolar loading. Furthermore, no significant differences were observed under cyclic loading to failure between any of the study groups.

INTERPRETATION

No considerable biomechanical advantage of using a conventional 1.5mm dorsal non-locking plate was identified over the novel 1.3mm lateral locking plate in the treatment of proximal phalanx fractures. Since the novel low-profile plate is less disruptive to the extensor mechanism, it should be considered as a valid alternative.

Two versus 3 lag screws for fixation of long oblique proximal phalanx fractures of the fingers: a cadaver study

PURPOSE

To compare 2- versus 3-screw fixation for oblique fractures of the proximal phalanx in a cadaver model that simulates active finger motion.

METHODS

We experimentally cut the proximal phalanges of the index, middle, and ring fingers of 9 cadaveric hands. Five fingers were assigned to a control group with no fixation, and 22 were fixed with either 2 or 3 lag screws. One digit was excluded because of iatrogenic fracture during preparation. The fingers were fitted with a differential variable reluctance transducer that measured maximum interfragment displacement while the fingers were subjected to 2,000 full flexion and extension cycles to simulate a 6-week active motion protocol.

RESULTS

Analysis of variance revealed a significant difference between the control group and both the 2- and the 3-screw group. The 2- and 3-screw group average displacements were not significantly different. Both of these groups were equivalent with a power of 90%.

CONCLUSIONS

Biomechanical stability during simulated active motion protocol did not differ in simulated proximal phalanx fractures treated with 2 lag screws or 3.

CLINICAL RELEVANCE

Fracture fixation using 2 screws may be more cost and time effective and, therefore, more attractive to the surgeon, even when 3 screws can be placed. Furthermore, surgeons may consider using 2 screws rather than resorting to plate fixation when 3-screw fixation is not possible for these types of fractures.

Comparison of treatment of oblique and spiral metacarpal and phalangeal fractures with mini plate plus screw or screw only

INTRODUCTION

We aimed to compare results of treatment of oblique-spiral metacarpal and phalangeal fractures with screw only or mini plate plus screw, respectively.

METHODS

A total of 43 patients who were operated with a diagnosis of displaced, irreducible, unstable, rotational oblique-spiral metacarpal and proximal phalangeal fracture between 2007 and 2010 were included in this study. The mean age of patients with a phalangeal fracture was 33.8 years (range 20-50 years; 4 females, 18 males), and the mean age of patients with a metacarpal fracture was 29.6 years (range 18-45 years; 3 females, 18 males). Mini plate plus screw or screw only was used for internal fixation of these fractures. The patients were followed up for 19.2 ± 5.4 months in the phalangeal fracture group and 20.9 ± 7.3 months in metacarpal fracture group. Of the metacarpal fractures, 14 were oblique and 10 spiral, whereas 14 of the phalangeal fractures were oblique and 8 spiral. The patients were evaluated according to total range of motion of the finger, grasping strength and Q-DASH score.

RESULTS

For patients treated with mini plate plus screw after metacarpal and phalangeal fractures, the time to return to work was significantly shorter in comparison to patients treated with screws only. There was no significant difference between patients with metacarpal fractures treated with mini plate plus screw and patients treated with screw only in terms of total range of motion and Q-DASH results at last on control examination, while results of patients with phalangeal fractures treated with screw only were significantly better. There was no significant difference between these two treatments in phalangeal fractures in terms of grasping strength of the finger in early (1st month) and late (last control examination), whereas patients with metacarpal fractures treated with mini plate plus screw reached higher grasping strength earlier.

CONCLUSION

Treatment with mini plate plus screw should be avoided in spiral and oblique phalangeal fractures, and fixation should be done with screw only with a short surgical incision and dissection. On the other hand, treatment with mini plate plus screw should be preferred in patients with spiral and oblique metacarpal fractures, especially in those who work in occupations requiring higher physical strength.

The biomechanics of fixation techniques for hand fractures

Multiple options are available for the fixation of metacarpal and phalangeal fractures; treatment options depend largely on the fracture characteristics, concomitant injuries, and surgeon preference. With an understanding of the options available and the biomechanics involved, appropriate treatment options may be chosen. Although plate and screw constructs provide the strongest fixation for these fractures, many other techniques provide adequate fixation and may be favored for reasons other than biomechanics.

Biomechanical comparison of pull-out force of unicortical versus bicortical screws in proximal phalanges of the hand: a human cadaveric study

BACKGROUND

Bicortical fixation of proximal phalangeal fractures may damage underlying flexor tendons secondary to drilling and screw protrusion in the dorsal-ventral direction. The aim of this study was to measure and compare the pull-out force of unicortical screws compared to bicortical screws in human cadaveric proximal phalanges to identify optimal configuration for internal fixation.

METHODS

Forty proximal phalanges were harvested. Bicortical and unicortical self tapping 1.7mm screws were inserted into paired phalanges at the distal and proximal metaphysis and at the mid-diaphysis placed in the dorso-ventral direction. Pull-out force of unicortical and bicortical screws were measured and compared.

FINDINGS

Bicortical screw pull-out force is significantly higher than that of unicortical screws in the dorsal-ventral direction. Pull-out strength of unicortical screws at the mid-diaphysis was significantly higher than the pull-out strength of bicortical screws at the proximal metaphysis (181.8N versus 31.5N, P<0.0001).

INTERPRETATION

Diaphyseal fixation is stronger than metaphyseal for both unicortical and bicortical configurations. Unicortical mid-diaphyseal is stronger than bicortical proximal metaphyseal screw pull-out strength. This study provides biomechanical data that may be helpful for individualizing fracture fixation techniques at the proximal phalanx.

Fixation choices for closed simple unstable oblique phalangeal and metacarpal fractures

Percutaneous K-wire fixation is still a useful technique for closed oblique phalangeal and meta-carpal fractures when an adequate closed reduction can be achieved. Lag screw fixation may be the best choice for open fixation of long oblique phalangeal and metacarpal fractures. For short oblique fractures, plating or tension band wiring is recommended. Plating provide rigid fixation to allow early mobilization; however, one may encounter frequent complications such as extensor lag, stiffness, or joint contracture when plating technique is used in phalangeal fractures. Tension band wiring technique at the phalangeal location may reduce such complications. Overall, successful outcomes of treating phalangeal and metacarpal fractures require a clear appreciation of fracture anatomy and pattern. It is mandatory for the treating surgeon to be familiar with all the treatment techniques discussed in order to tailor a specific technique for a particular injury and patient type.

Principles of metacarpal and phalangeal fracture management: a review of rehabilitation concepts

Patients with common hand fractures are likely to present in a wide variety of outpatient orthopedic practices. Successful rehabilitation of hand fractures addresses the need to (1) maintain fracture stability for bone healing, (2) introduce soft tissue mobilization for soft tissue integrity, and (3) remodel any restrictive scar from injury or surgery. It is important to recognize the intimate relationship of these 3 tissues (bone, soft tissue, and scar) when treating hand fractures. Fracture terminology precisely defines fracture type, location, and management strategy for hand fractures. These terms are reviewed, with emphasis on their operational definitions, as they relate to the course of therapy. The progression of motion protocols is dependent on the type of fracture healing, either primary or secondary, which in turn is determined by the method of fracture fixation. Current closed- and open-fixation methods for metacarpal and phalangeal fractures are addressed for each fracture location. The potential soft tissue problems that are often associated with each type of fracture are explained, with preventative methods of splinting and treatment. A comprehensive literature review is provided to compare evidence for practice in managing the variety of fracture patterns associated with metacarpal and phalangeal fractures, following closed- and open-fixation techniques. Emphasis is placed on initial hand positioning to protect the fracture reduction, exercise to maintain or regain joint range of motion, and specific tendon-gliding exercises to prevent restrictive adhesions, all of which are necessary to assure return of function post fracture.

The role of soft tissues in plate fixation of proximal phalanx fractures

The tension band effect of plate fixation and the contribution of soft tissues to that effect was examined biomechanically in human proximal phalanges. Forty-six proximal phalanges in whole cadaver hands with all soft tissues in place (intact) and 43 proximal phalanges stripped of soft tissues (denuded) were tested. After midshaft osteotomy, each proximal phalanx was fixed internally with a dorsal minicondylar plate, a lateral minicondylar plate, a dorsal straight plate, or a lateral straight plate. Specimens were tested in three-point apex dorsal bending to clinical failure, defined as 30 degrees angulation. Ultimate moment (stability) at this angulation was similar among the four fixation methods in the specimens with all soft tissues intact. Stability also was similar among these methods in the denuded specimens. There were no significant differences in stability between minicondylar and straight plates or between dorsal and lateral plates in the specimens with soft tissues, nor were there significant differences between these groups in the denuded specimens. The stability of the four fixation methods was significantly greater in the specimens with soft tissues than in the denuded specimens. Soft tissues increased the stability of lateral minicondylar plates by 163%, lateral straight plates by 157%, dorsal minicondylar plates by 126%, and dorsal straight plates by 104%, providing a dorsal tension band effect that counteracted the buttress (compression) of the volar fracture surfaces of the phalanx. The results suggest that in the clinical setting a laterally placed straight or minicondylar plate may provide as much stability to a phalanx with a midshaft fracture as does the traditional, more invasive dorsally placed minicondylar or straight plate. These findings must be evaluated with caution, however, because all specimens were from embalmed cadavers, and the formalin fixation may have augmented the stability and stiffness of the soft tissues in the intact specimens. A subsequent pilot study comparing intact proximal phalangeal specimens that were formalin-fixed with those that were fresh-frozen showed a significant increase in stability and stiffness of formalin-fixed specimens.

Rigid internal fixation of basilar fractures of the proximal phalanges by cancellous bone grafting only

Ten patients with 13 basilar metaphyseal impaction fractures of the proximal phalanges of the fingers were treated with "rigid internal fixation" by bone grafting alone. When retrospectively reviewed at a mean follow-up of 32 months, bone healing had occurred without any relevant secondary displacement of the fracture fragments. The final ranges of motion were good and return to work was quicker than expected.

Treatment of phalangeal fractures by tension band wiring

This retrospective study assessed the outcomes of 30 patients with phalangeal fractures which were treated by open reduction and tension band wiring. Oblique, transverse and comminuted extraarticular fractures, as well as intraarticular fractures, were treated with this technique and they all united in about 8 weeks. There were no significant complications. At a mean follow-up period of 2.3 years, the active range of movement of the involved fingers was excellent in 17, and good in 13 instances. There were no fair or poor results.

Intramedullary fixation by resorbable rods in a comminuted phalangeal fracture model. A biomechanical study

The mechanical rigidity of three different methods of resorbable intramedullary fixation (bone peg, and polyglycolide rods with and without interlocking) was assessed in a comminuted phalangeal fracture model and the results compared with two commonly used internal fixation devices (lateral plate, crossed K-wires) in a cadaver model. Each fixation technique was tested for its biomechanical strength in apex palmar bending, compression and torsion. Failure testing for the three resorbable methods was also done. The results showed that lateral plating provided the best rigidity in apex palmar bending and torsion, followed by intramedullary bone peg fixation. All resorbable intramedullary fixations had rigidity that was at least the same as crossed K-wires. For the torque test, polyglycolide rods with interlocking provided better rigidity than without interlocking. There was no significant difference between the different methods in the compression test, except that the intramedullary bone peg was significantly stiffer than K-wires.

Biomechanical properties of absorbable implants in finger fractures

The mechanical rigidity of five different methods of pin fixation in two proximal phalangeal fracture models was studied and absorbable implants were compared with metallic implants in a biomechanical cadaver study. Thirty phalanges were tested in apex palmar bending, compression and torsion. Results showed that rigidity of absorbable implants was comparable with metallic implants, except in torsion.

Comparison of the size of plates for fracture fixation with the size of phalanges and metacarpals in cadavers of Asian origin

The size and volume of plates and screws for fracture fixation of the hand (1.5-mm screws and titanium miniplates, 2.0-mm screws and stainless-steel AO miniplates, and 2.7-mm screws and stainless-steel AO miniplates) were compared against the phalanges and metacarpal bones and the surrounding soft tissue from male cadavers of Asian decent. In the cadaver study, it was first established that the difference between anatomic measurements and radiologic measurements for the interarticular bone length and midshaft width were not significant (p = .09). Second, the volume occupied by the bone showed a close association to interarticular bone length. This finding would suggest that the volume occupied by the bone may be estimated from the radiographs. When the length of the plates was compared to that of the bones, the analysis showed 4-hole and 6-hole 1.5-mm titanium miniplates, and the 4-hole and 6-hole 2.0-mm AO plates were not suitable for the middle phalanx, although only rarely are fractures in the middle phalanx fixed with plates. For the proximal phalanx, only the 4-hole 1.5-mm and 2.0-mm plates were suitable in length. The 6-hole 2.0-mm AO plate was found to be suitable for only the longer proximal phalanx of the middle digit. For the metacarpals, the 5-hole 2.7-mm AO plate was found not to be suitable for the thumb (in length) and the ring digit (in width). The commonly used plates and screws for fracture fixation of the hand may not be suitable in size for groups of people with smaller hand sizes, in particular some Asians and women.

External fixation for comminuted phalangeal fractures. A biomechanical cadaver study

The mechanical rigidity obtained by external fixation in a comminuted phalangeal fracture model was assessed and the results compared with two other types of internal fixation commonly used (lateral plate and crossed Kirschner wires) in a biomechanical cadaver study. Each fixation technique was tested in apex palmar bending, compression and torsion. The results showed that lateral plating provided the best rigidity in apex palmar bending and compression and that external fixation and Kirschner wires showed the same mechanical properties. For the torque test, external fixation provided the best rigidity.

Fixation for comminuted phalangeal fractures. A biomechanical study of five methods

The rigidities of five fixation methods have been studied with a comminuted phalangeal fracture model. Mechanical testing of compression, bending and torsion were performed for each fixation. Lateral plating with six screws seems to provide the most rigid fixation. If such lateral plating is not practicable, the four-Kirschner wire method would be a satisfactory alternative.

A comparative mechanical analysis of plate fixation in a proximal phalangeal fracture model

A biomechanical study compared the mechanical properties of hand and craniofacial plating systems commonly used in proximal phalangeal fractures. Two plates of each of the various systems were mounted dorsally on a yellow-birch-dowel model of a proximal phalanx after a transverse cut was made in the middle of the section of the dowel, modeling a midshaft transverse osteotomy or fracture. Torsional rigidity, as well as four-point bending rigidity in apex dorsal, lateral and volar directions, was achieved. Failure testing in apex palmar four-point bending was then examined. Between plating systems, torsion varied 1,600% and results of apex palmar testing varied 1,500%. Apex palmar moment-to-failure testing varied 1,000% and represented a 3.5%-38% range of intact proximal phalangeal strength. This also represented 12%-128% of the maximum calculated in vivo bending moments of the proximal phalanx. The wide variation in plate strengths and stiffness raises questions as to the suitability of certain plating systems with regard to early mobilization. Moreover, some plating systems tested were mechanically weaker than the reported strengths of certain Kirschner wire fixation techniques.

Internal fixation of oblique metacarpal fractures. A biomechanical evaluation by impact loading

Internal fixation of oblique metacarpal fractures was studied in a cadaver model by impact loading. One hundred twenty fresh-frozen human metacarpals underwent compressive and bending impacts after oblique osteotomy and internal fixation. Dorsal plating with lag screws, 2 dorsal lag screws (2-screws), crossed Kirschner wire tension band (crossed K-wire), 5 stacked intramedullary Kirschner wire (5-rod), and paired intramedullary Kirschner wire (2-rod) were used. The failure occurred within 6 msec in the compressive impact and was almost immediate in the bending impact. The dorsal plate and the intramedullary rod fixations were the strongest and were not significantly different from the intact specimens in compressive impact; they were, however, 19% weaker in bending impact. The 2-screws was the weakest fixation in this group. This fixation was 59% weaker in compressive impact and 47% weaker in bending impact compared with the dorsal plating.

Mini and micro plating of phalangeal and metacarpal fractures: a biomechanical study

Biomechanical testing was performed in a cadaver model to evaluate the effects of plate size and position on fracture stability using Leibinger mini and microplates applied on the proximal phalanx and metacarpal. Fresh frozen cadaveric metacarpal and proximal phalanges were subjected to a midshaft transverse osteotomy followed by application of titanium mini (1.7 mm screw diameter) and micro (1.2 mm screw diameter) plates/screws. For the metacarpal, a dorsal miniplate, a dorsal microplate, and bilateral microplates were used. For the proximal phalanx, similar plate configurations and sizes were used with the addition of a unilateral microplate. A three point bending model with both dorsal and palmar apex loading was used for all configurations. This study confirms that a dorsally applied miniplate provides the greatest rigidity to a dorsal apex load.

Comparative fatigue strengths and stabilities of metacarpal internal fixation techniques

To study quantitative differences in the fatigue strength and stability obtained with 5 types of internal fixation of metacarpal fractures, 105 preserved human metacarpals were cyclically tested in bending, torsion, and axial loading after oblique osteotomies of the metacarpal and internal fixation. The dorsal plate with lag screw was superior in all modes, followed by the two dorsal lag screws, crossed Kirschner wire tension banding, and intramedullary Kirschner wire fixation. The five intramedullary and the paired intramedullary Kirschner wire fixations were not statistically different. The fatigue life of the plate fixation was significantly larger in bending (1.5 times), torsion (1.6 times), and axial loading (2.5 times) than the second strongest fixation, two dorsal lag screws. Its initial rigidity was significantly higher in axial loading (1.5 times) but was not statistically different in bending and torsion.

Spiral fracture fixation techniques. A biomechanical study

The mechanical strengths of five common fixation techniques for spiral fractures have been tested. A total of 240 cadaver metacarpals and proximal phalanges were fractured and fixed by either crossed K-wires, interosseous loops, a dorsal mini-plate, a single compression screw or K-wire plus cerclage wire. Specimens were subjected to torsional and cantilever bending tests. A single compression screw provided the best overall fixation for the proximal phalanx. In addition, a single compression screw provided better fixation than any of the other techniques when proximal phalanges and metacarpals were subjected to torsional tests (P < 0.05). In apex dorsal bending tests of metacarpals, the screw provided fixation superior to interosseous wires, crossed K-wires, or dorsal mini-plates (P < 0.05). These results indicate that the use of a single compression screw provides the most satisfactory biomechanical advantage for spiral fracture fixation.

Biomechanical analysis of mallet finger fracture fixation techniques

A biomechanical study was conducted to determine the best fixation technique for mallet finger fracture among four commonly used methods. Considerations were technical complications, biomechanical properties, and maintenance of reduction. Techniques tested included Kirshner wire, figure-of-eight wire, tension band wire, and tension band suture. Technical complications were frequent with both the Kirschner wire and tension band wire techniques. Biomechanical testing yielded significantly greater energy absorbed to failure and a trend toward greater peak loads to failure for both the figure-of-eight wire and tension band suture techniques. Irreversible loss of reduction during testing occurred in all of the Kirschner wire-fixed fractures, in 60% of the tension band wire-fixed fractures, and in 50% of the figure-of-eight wire-fixed fractures. No irreversible failure occurred in the tension band suture group.

Internal fixation of metacarpal and phalangeal fractures with AO minifragment screws and plates: a prospective study

In a prospective study, 43 patients with 47 metacarpal or phalangeal fractures with significant displacement, rotation, angulation and/or instability were treated with internal fixation using AO minifragment screws and plates. In all fractures an anatomical reduction was achieved. Postoperatively all metacarpal fractures were protected by means of a plaster, in which motion was allowed, whereas all phalangeal fractures were treated by means of a soft bandage. At a review after a mean period of 28 months, 31 patients with 35 fractures out of 34 patients with 38 fractures had regained excellent recovery of total active flexion (92 per cent). Three patients had a poor recovery of total active flexion; one had an infection, the other two were operated on 6 and 14 days after their injury, whereas the mean delay between injury and operation was 3 days. All patients not reviewed had regained good or 100 per cent function.

Biomechanical and functional testing of plate fixation devices for proximal phalangeal fractures

Functional testing in fresh cadaver digits of a dorsally applied mini-H plate, a mini-straight plate, and a laterally applied mini-condylar plate demonstrated that all three significantly reduce (p less than 0.2) simulated active PIP joint flexion. The mini-condylar plate, however, provided the least reduction of any of the three plates. Biomechanical testing of the same three plates on proximal phalanx after osteotomy in apex palmar and apex dorsal direction bending showed all three plates to provide rigidity less than the intact bone.

Clinical application of sapphire pins as an internal fixation device for the upper extremity

Since June 1980, sapphire pins (monocrystalline alumina ceramic pins) have been used in 22 patients as an internal fixation device for hand and elbow problems. In our follow-up studies, good bone healing was observed in all cases except for one delayed union in a fracture of the diaphysis of the proximal phalanx. Radiographs showed no pin migration or osteolytic reaction around the pins. We therefore conclude that our device and its insertion technique can be successfully applied to intraarticular fractures and fractures in the vicinity of the joint.

Ninety-ninety intraosseous wiring for internal fixation of the digital skeleton

Ninety-ninety intraosseous wiring has been used in more than 150 cases over the last 4 years to obtain skeletal stability. This technique has been effective for the internal fixation of replanted parts, arthrodeses, transverse fractures, and elective free-tissue transfers. All osteotomies and fractures healed promptly, usually within 6 weeks. There have been no instances of nonunion, malunion, or implant failure. Only one wire had to be removed due to its prominence. Ninety-ninety intraosseous wiring is an expeditious, straightforward, and very stable method to secure rigid internal fixation and allow early active motion of the digital skeleton.

Comparative mechanical properties of various Kirschner wire configurations in transverse and oblique phalangeal fractures

A biomechanical study assessed the comparative mechanical properties of various wire configurations used in transverse and oblique phalangeal fractures. The configurations included crossed, oblique, and intramedullary wire techniques using 0.028-inch diameter (d) or 0.035-inch d Kirschner (K) wires. Six different configurations were tested in both the oblique fracture pattern and in the transverse fracture pattern. The mechanical properties were determined after either oblique or transverse osteotomy and fixation of the proximal phalanx. Each fixation technique was tested in apex palmar, apex dorsal, and lateral bending, as well as in torsion and distraction. The results showed that of the configurations tested, four crossed 0.028-inch d Kirschner wires obtained the highest rigidity in the transverse fracture pattern and three oblique 0.035-inch d Kirschner wires obtained the highest rigidity in the oblique fracture pattern.