Torque resistance after fixation of Jones fractures with intramedullary screws

BACKGROUND: Intramedullary screws frequently are used for fixation of Jones fractures of the fifth metarsal. While the ability of intramedullary screw fixation in fifth metatarsals to resist bending and tensile forces is well known, the ability to withstand torsion has not been studied. This paper compares the torsional stiffness of Jones fractures treated with 6.5-mm short- threaded intramedullary screws to those treated with 5.0-mm cannulated short-threaded intramedullary screws. METHODS: Nine fresh-frozen, matched pairs of cadaver fifth metatarsals had an acute Jones fracture simulated with an osteotomy. They were stabilized with intramedullary screws and then loaded to failure. RESULTS: The torsional stiffness of the metatarsals fixed with the 6.5-mm did not differ significantly from that using 5.0-mm screws. However, to achieve stability, the 5.0-mm screw had to be long enough to reach the metatarsal head and neck. This tended to straighten the normally curved fifth metatarsal bone and caused lateral gapping at the fracture site. CONCLUSION: Both 5.0-mm or 6.5-mm screws provide equal torsional rigidity, but 5.0-mm screws may need to be longer, which could potentially straighten the fifth metatarsal shaft in patients who have a curved fifth metatarsal.     

Intramedullary screw fixation of Jones fractures

BACKGROUND: Jones fractures of the fifth metatarsal can be stabilized using intramedullary screw fixation techniques. A range of screw diameters from 4.5 mm to 6.5 mm can be used, but the optimal screw for this procedure has yet to be defined. In clinical practice, we have observed that failure is more likely when smaller diameter screws are used. METHODS: Experimental Jones fractures were created in 23 pairs of human cadaver fifth metatarsals, which were fixed using either 5.0 mm or 6.5 mm screws. Fracture stiffness and pull-out strengths were measured for either screw type and their relationships with bone mineral density and medullary canal diameter were determined. RESULTS: There was no significant difference in the bending stiffness of fractures stabilized with 5.0 mm and 6.5 mm screws; however, different mechanisms of failure were noted for either screw type. Poor thread purchase within the medullary canal was noted with the 5.0 mm screws, while excellent purchase was noted with 6.5 mm screws. Pull-out strength testing revealed significantly higher pullout strengths for the larger 6.5 mm screws. There was no significant difference in bone mineral density or medullary canal diameter between right and left metatarsals. CONCLUSIONS: Fifth metatarsals can often accommodate a 6.5 mm screw for the stabilization of Jones fractures. Larger diameter screws did not result in greater fracture stiffness in our model, but did result in significantly greater pull-out strengths. CLINICAL RELEVANCE: Larger diameter screws may be more appropriate for intramedullary screw fixation of Jones fractures.     

Torsional strains in the proximal fifth metatarsal: implications for Jones and stress fracture management

BACKGROUND: Reports of nonunion of proximal fifth metatarsal fractures treated by internal fixation indicate that current fixation methods do not always adequately address the stresses to which the bone is subjected during ambulation. In particular, the insertion sites of the peroneus brevis and peroneus tertius tendons on the fifth metatarsal suggest that their actions can impose torsional stresses on the areas of the bone in which Jones fractures and stress fractures occur. Intramedullary screw fixation, however, offers little resistance to rotation of the proximal and distal fragments relative to one another. METHODS: To determine the potential for the existence of torsional stresses in the fifth metatarsal during post-operative ambulation, a simplified cadaver model of single-limb stance was used in which cadaver feet were subjected to concurrent axial and tendon forces while monitoring the outputs of stacked rosette strain gauges placed at the typical sites of Jones and stress fractures. Principal strain and shear strain magnitudes and directions were measured. RESULTS: The shear strain magnitudes and strain axis directions indicated the presence of torsional stresses in the underlying bone potentially capable of causing internal rotation of the proximal fragment relative to the distal end of the bone. CONCLUSIONS: This finding has implications for the treatment of both Jones fractures and stress fractures of the proximal fifth metatarsal. An internal fixation device that has the capability to resist torsion as well as tension and bending would appear optimal to treat these fractures.     

Screw Length Associated With Fracture Gapping of Fifth Metatarsal Base Fracture With Intramedullary Screw Fixation: A Cadaveric Study

Intramedullary screw fixation is a well-established surgical treatment for fifth metatarsal Jones fractures, due to its minimally invasive nature, and potential early return to activity. Due to the curvature of the fifth metatarsal, optimal length of the screw is needed to prevent gapping at the fracture site. The placement of a straight screw induces straightening of a naturally curved bone. The purpose of this study was to aid surgeons in determining an appropriate screw length for intramedullary fixation of a fifth metatarsal Jones fracture in order to prevent fracture gapping. A transverse osteotomy of the fifth metatarsal was made in 10 cadaver specimens at the level of a traditional Jones fracture. Inserted screws were sequentially increased in length until plantar gapping at the fracture site was noted. The angle (degree) of plantar gapping was measured with each increase in screw length and diameter. The mean length of the cadaveric fifth metatarsals was 73.76 mm (range 67.42-81.73). The mean screw length that caused gapping at the fracture site was 49.89 mm (range 44-55), representing 67.05% (range 61.26-75.35) of the fifth metatarsal length. The correlation coefficient revealed that gapping of the fracture site is most likely to occur when the screw length is 66% the length of the metatarsal length (r_s = 0.66; 95% confidence interval: 0.06-0.91; p = .04). The angle of the initial gapping was 2.85° (range 2°-4°). With an incremental increase in screw length, the angle was 3.85° (range 3°-6°), and with an incremental increase in screw diameter, the angle was 3.70° (range 2°-5°). Our study demonstrated that screw lengths exceeding 66% of the metatarsal length lead to plantar fracture gapping. Additionally, gapping was accentuated with larger diameter screws due to angle variance.     

Intramedullary screw fixation of the fifth metatarsal: an anatomic study and improved technique

Intramedullary screw fixation has been found to be a reliable treatment for certain fractures of the fifth metatarsal. Techniques for this treatment have been described relying largely on intraoperative fluoroscopy. Ten human cadaver specimens had their fifth metatarsals osteotomized and underwent retrograde intramedullary pin placement. Anatomic landmarks and the location of the sural nerve in relation to this starting point were measured. The trajectory of a pin reducing the osteotomy was analyzed. Using the resultant starting point and guide pin trajectory, intramedullary screw placement was performed reliably without the aid of fluoroscopy. This study demonstrates that intramedullary screw fixation of proximal fifth metatarsal fractures may be performed with the use of anatomic landmarks, which decreases the amount of intraoperative fluoroscopy needed.     

Intramedullary screw fixation of Jones fractures: a biomechanical study.

The management of proximal fifth metatarsal ("Jones") fractures in athletes has become increasingly more aggressive, despite a lack of biomechanical data in the literature. A cadaver biomechanical study was conducted to evaluate the strength of intramedullary fixation of simulated Jones fractures loaded to failure via three-point bending on a Materials Testing System machine. In a series of eight intact fifth metatarsal control specimens, the force to failure (fracture) was measured for comparison with repaired specimens. Acute fractures were simulated in 10 pairs of feet via osteotomy at the typical fracture location and were fixed with either a 4.5-mm malleolar screw or a 4.5-mm partially threaded, cancellous, cannulated screw, both placed using conventional intramedullary techniques. Force at initial displacement averaged 73.9 N (SD, 64.7 N) for the malleolar screws and 72.5 N (SD, 42.3 N) for the cannulated screws. Force at complete displacement averaged 519.3 N (SD, 226.2 N) for the malleolar screws and 608.4 N (SD, 179.7 N) for the cannulated screws. The force to failure of the intact specimens was significantly greater than the initial and complete forces to failure for the fixed specimens (P < 0.05, independent measures analysis of variance). There was no statistical difference between the average forces at initial displacement or at complete displacement in the fixed metatarsal specimens for the two different types of screws, but the forces at complete displacement for each screw type were significantly greater than the forces at initial displacement (P < 0.05). On the basis of literature review and data generated from this study, it is apparent that the forces necessary to cause displacement of the stabilized Jones fracture are above what would be transmitted within the lateral midfoot during normal weightbearing. The choice of screw and intramedullary technique of fixation is a matter of surgeon preference, because the choice of screw makes no biomechanical difference.     

Intramedullary screw fixation of proximal fifth metatarsal fractures: a biomechanical study

Intramedullary screw fixation is a popular technique for treatment of proximal fifth metatarsal fractures. The purpose of this study was to compare the fixation rigidity of a 5.5 mm partially threaded cannulated titanium screw, with presumed superior endosteal purchase, to a similar 4.5 mm screw. Acute fifth metatarsal fractures were simulated in cadavers, stabilized with intramedullary screws, and loaded to failure in three-point bending. The initial failure loads for the metatarsals fixed with 4.5 mm and 5.5 mm screws were not significantly different (332.4 N vs. 335.2 N, respectively), nor were the ultimate failure loads (849.8 N vs. 702.2 N, respectively). Based upon our results, maximizing screw diameter does not appear to be critical for fixation rigidity and may increase the risk of intraoperative or postoperative fracture.     

Jones type fifth metatarsal fracture fixation in athletes: A review and current concept

Jones type fifth metatarsal fracture is a common occurrence among athletes at all levels. These fractures may occur due to several mechanisms, but inversions and twisting injuries are considered some of the leading causes in sports. However, while Jones fracture incidences are frequent in the sporting world, there is still a lack of consensus on how such fractures should be effectively managed. There are numerous treatment options for patients with fifth metatarsal Jones fractures. The role of nonoperative treatment remains controversial, with concerns about delayed union and nonunion. Surgical stabilization of metatarsal Jones fractures is therefore often recommended for athletes, as it is often associated with a low number of complications and a higher rate of union than nonoperative management. This review will focus on literature regarding the prevalence of Jones type fifth metatarsal fracture, alongside the efficacy of both conservative and surgical treatment within this population.     

The Use of Percutaneous Screw Fixation Without Fracture Site Preparation in the Treatment of Fifth Metatarsal Base Nonunion

Nonunion after a proximal fifth metatarsal fracture can cause considerable pain, with high morbidity and loss of work. Although many authors advocate early surgical management of zone 3 injuries (Jones fractures), zone 1 and 2 fractures are generally expected to heal with conservative management. Uncommonly, zone 1 and 2 fractures can develop nonunions. The aim of this study was to evaluate the efficacy of closed intramedullary screw fixation for nonunions of the fifth metatarsal base. We performed a prospective study involving all fifth metatarsal base nonunions treated in our department over 2 years. Only minimally displaced adult fractures were considered for this study. The fracture pattern was categorized using the Dameron classification (zone 1, styloid process; zone 2, metadiaphyseal area; zone 3, proximal diaphysis). All nonunions were fixed percutaneously under radiographic guidance, without fracture site preparation. Zone 1 injuries were fixed using a 3-mm headless compression screw, and those of zones 2 and 3, with an intramedullary 4-mm screw. Of 30 patients included in this study, a minimum 6-month clinical follow-up was obtained. The average time from injury to treatment was 5.9 months (range 3 to 36). There were no smokers in this patient cohort. There were 12 zone 1 injuries, 9 zone 2 injuries, and 9 zone 3 injuries. All patients achieved union by 3 months after screw fixation, with 29 of 30 achieving union by 6 weeks. All patients had resolution of symptoms. There were no complications. We conclude that percutaneous fixation of fifth metatarsal base nonunions, without fracture site preparation, achieves excellent results. We believe that the screw alters the strain of the fracture, thus promoting fibrous-to-osseous conversion and therefore union.     

Bending stiffness and pull-out strength of tapered, variable pitch screws, and 6.5-mm cancellous screws in acute Jones fractures

BACKGROUND: Stabilization of fifth metatarsal Jones fractures with intramedullary screws is popular, particularly in athletes, because nonoperative treatment involves prolonged casting and a distinct risk of nonunion or delayed union. Conventional lag screws of various diameters are routinely used for Jones fracture fixation. More recently, tapered, headless, variable pitch screws have become available as an option. These screws have the advantage of not having a protruding screw head, but information regarding their performance in Jones fracture fixation is limited. To determine whether differences exist in the mechanical integrity of fifth metatarsals fixed with each type of screw, this study was designed to compare Jones fracture fixation with 6.5-mm partially-threaded lag screws and headless, tapered, variable pitch compression screws with a 4-mm leading-thread diameter and 5-mm trailing-thread diameter. METHODS: Simulated Jones fractures were created in 20 matched pairs of fresh-frozen fifth metatarsals. One bone from each pair was stabilized with a tapered, variable pitch screw, and the contralateral with a 6.5-mm partially-threaded cancellous lag screw. The stiffness in lateral-to-medial bending of the resulting constructs and the resistance of the screws to pulling out of the distal fragment were quantified. RESULTS: There was no demonstrable difference in bending stiffness between metatarsals fixed with the two types of screws (p = 0.688). The 6.5-mm screw provided significantly higher resistance to pull-out (p = 0.001). CONCLUSIONS: Headless, tapered, variable pitch compression screws of the size tested are not entirely comparable to 6.5-mm lag screws in this application. They are effective in resisting bending but do not offer equivalent resistance to thread pull-out.     

Fifth metatarsal tuberosity fracture fixation: a biomechanical study

This study tested the hypothesis that fixation of a fifth metatarsal tuberosity fracture with a lag screw that engages the intact medial cortex is biomechanically stronger than fixation with a long intramedullary screw (control). The right and left feet from 10 male cadavers were alternately assigned to the two fixation groups. After fracture reduction and fixation, each specimen was potted in acrylic cement and tested on a servohydraulic testing machine. The repairs were then distracted until failure by placing the peroneus brevis tendon under tension at a rate of 1 mm/s. The lag screw technique resulted in a significantly greater mean (+/- SD) load to failure (150 +/- 90 N) than did intramedullary screw fixation (70 +/- 60 N) (p < .05) and may offer a useful method of internal fixation of fifth metatarsal tuberosity fractures when surgical stabilization is indicated.     

LCP distal ulna hook plate as alternative fixation for fifth metatarsal base fracture

Intramedullary screw fixation is the most common treatment for fifth metatarsal base fractures. Screw application does not achieve accurate reduction in fracture with small fragments, osteoporotic bone, or Lawrence zone 1 fractures, however. On the basis of similar anatomical architectures between the distal ulna and the fifth metatarsal base, the purpose of this study was to assess the results of a locking compression plate (LCP) distal ulna hook plate in stabilizing displaced zone 1 or 2 fifth metatarsal base fractures. Nineteen patients with Lawrence zone 1 (n = 12) or 2 (n = 7) fractures of the fifth metatarsal base were treated surgically with an LCP distal ulna hook plate. The patients were evaluated clinically and radiographically, and functional outcomes were graded by using the American Orthopaedic Foot and Ankle Society (AOFAS) midfoot scoring system. Radiographic bony union was obtained in all patients, at an average of 7.4 weeks. The mean AOFAS midfoot score improved from 26 (range, 0–45) preoperatively to 94 (range, 72–100) points at the final follow-up. There were three patients with post-traumatic cubometatarsal arthrosis and one patient with sural nerve neuropraxia. In our experience, the distal ulna hook plate achieves a high rate of bony consolidation and anatomically suitable fixation in zone 1 or 2 fifth metatarsal base fractures. We also suggest that the LCP distal ulna hook plate should be considered as an alternative treatment in multifragmentary, osteoporotic, and tuberosity avulsion (zone 1) fifth metatarsal base fractures.     

Interventions for treating proximal fifth metatarsal fractures in adults: A meta-analysis of the current evidence-base

Background

This study assessed the clinical and radiological outcomes of different non-surgical interventions, surgical versus non-surgical interventions, and different surgical interventions used in the management of proximal fifth metatarsal fractures.

Methods

A systematic review of published and unpublished literature was undertaken.

Results

Six studies, assessing 330 patients and 333 fractures of the proximal fifth metatarsal were reviewed. Four studies assessed outcomes following tuberosity fractures, whilst 2 studies recruited patients following proximal diaphyseal or Jones fractures. The findings suggested that bandage is superior to below knee cast immobilisation for patient-reported functional and pain scores, with no difference in fracture union or re-fracture, and a shorter duration to return to work. There was no significant difference in complication rates or functional outcomes for patients managed in a plaster slipper compared to a bandage post-injury. When comparing surgical and non-surgical management, intramedullary screw fixation results in a shorter time to fracture union, reduced complication rates and earlier return to pre-injury activities compared to non-surgical cast immobilisation. However, the evidence-base is limited in it size and presented with a number of methodological limitations.

Conclusions

Further well-conducted randomised controlled trials are required to determine the optimal management strategy for the different types of proximal fifth metatarsal fractures.     

Fractures of the Proximal Fifth Metatarsal: Selecting the Best Treatment Option

Because of circulatory differences in the three zones of the proximal fifth metatarsal, the location of a fracture must be considered when selecting treatment. The most proximal portion of the base of the fifth metatarsal has good blood supply. Fractures in this zone usually extend into the fifth metatarsocuboid joint. The second zone is associated with Sir Robert Jones, who in 1902 first asserted that fractures of the fifth metatarsal are commonly caused by indirect violence. Fractures in this zone take longer to heal than more proximal fractures, and treatment should be individualized. Whether to use a functional metatarsal brace, a stiff-soled shoe, a short-leg cast, or even internal fixation with a screw depends on the patient's lifestyle and desired activity level. Fractures in the third zone occur between the distalmost portion of the metaphysis and the proximal 1.5 cm of the diaphyseal tubular bone. This zone begins just distal to the ligamentous complex holding the proximal fourth and fifth metatarsals together. In active athletes, fractures in this zone often are stress injuries. For anatomic and mechanical reasons, such fractures are the most difficult to heal. Without surgical treatment, they may take 2 to 21 months to unite and are therefore more likely to need aggressive treatment.     

Biomechanical Comparison of Cannulated Screw Osteosynthesis With Tension-Band Wiring for Proximal Fractures of the Fifth Metatarsal (Jones Fracture)

Jones fractures, which lie at the junction of the diaphysis to the metaphysis of the fifth metatarsal, are a well-described clinical issue. There are various surgical approaches, including the commonly performed cannulated screw osteosyntheses, and the less frequently used tension-band approach. The aim is to compare the biomechanical stability of these osteosyntheses. We performed an osteotomy on 16 fresh frozen fifth metatarsal bones from body donors representing a Jones fracture. The fractures were treated pairwise with screw osteosynthesis or tension-band wiring. This was followed by cyclic axial bending until osteosynthesis failure. Stability under axial bending force was higher in the screw osteosynthesis (mean: 70.0 ± 66.5 N) compared to the tension-band wiring (mean: 35.7 ± 23.3 N) group although not reaching statistical significance (p = .116). The study shows no statistically significant difference in biomechanical stability under axial loading between screw osteosynthesis and tension band wiring. Based on the data obtained, no differences can be observed from a biomechanical point of view. The study supports the established method of treating Jones fractures primarily with screw osteosynthesis. In addition, the data suggest that tension band wiring may be a good alternative osteosynthesis, for example, after failed casting treatment or failure of primary osteosynthesis.     

Metatarsal fractures

Metatarsal fractures are relatively common and if malunited, a frequent source of pain and disability. Nondisplaced fractures and fractures of the second to fourth metatarsal with displacement in the horizontal plane can be treated conservatively with protected weight bearing in a cast shoe for 4-6 weeks. In most displaced fractures, closed reduction can be achieved but maintenance of the reduction needs internal fixation. Percutaneous pinning is suitable for most fractures of the lesser metatarsals. Fractures with joint involvement and multiple fragments frequently require open reduction and plate fixation. Transverse fractures at the metaphyseal-diaphyseal junction of the fifth metatarsal ("Jones fractures") require an individualized approach tailored to the level of activity and time to union. Avulsion fractures of the fifth metatarsal bone are treated by open reduction and tension-band wiring or screw fixation if displaced more than 2 mm or with more that 30% of the joint involved. The metatarsals are the most common site of stress fractures, most of which are treated nonoperatively. Symptomatic posttraumatic deformities need adequate correction, in most cases by osteotomy across the former fracture site.     

Tailor's bunion: clinical evaluation and correction by distal metaphyseal osteotomy with cortical screw fixation

Fifth metatarsal distal metaphyseal osteotomy represents a very common surgical procedure performed for tailor's bunion deformity. The authors advocate using a cortical bone screw for fixation device offers many advantages over conventional devices (i.e., Kirschner wire). The purpose of this paper is to offer a means to thoroughly evaluate tailor's bunion deformity clinically, biomechanically, and radiographically. This will allow the podiatric surgeon to choose a procedure of choice to correct the deformity. The technique of fifth metatarsal distal metaphyseal osteotomy with cortical bone screw fixation using AO4 principles is fully described.     

Relative stability of tension band versus two-cortex screw fixation for treating fifth metatarsal base avulsion fractures.

This study assesses the strength of fixating avulsion fractures of the fifth metatarsal base with a 4.0-mm partially threaded cancellous screw crossing two cortices as compared to tension banding. Our data showed statistically significant fixation strength improvement over tension banding for avulsion fractures (p < 0.02) in both polystyrene foam models and fresh, nonpreserved frozen cadaveric samples. In cadavers, the screw fixations were able to withstand more than three times the load sustained by the tension band fixations. The study utilized the Instron 8500 tensiometer to apply physiologic loads to test the constructs until failure. The displacement and load data at failure show the limitations of both fixations. By increasing the load resistance while maintaining compression, the bicortical cancellous screw fixation created greater stability at the avulsion fracture of the fifth metatarsal base as compared to tension band stabilization.     

Treatment strategies for acute fractures and nonunions of the proximal fifth metatarsal

There are at least three distinct fracture patterns that occur in the proximal fifth metatarsal: tuberosity avulsion fractures, acute Jones fractures, and diaphyseal stress fractures. Each of these fracture patterns has its own mechanism of injury, location, treatment options, and prognosis regarding delayed union and nonunion. Tuberosity avulsion fractures are the most common in this region of the foot. The majority heal with symptomatic care in a hard-soled shoe. The true Jones fracture is an acute injury involving the fourth-fifth intermetatarsal facet. These injuries are best treated with non-weight-bearing cast immobilization for 6 to 8 weeks. The rate of successful union with this treatment has been reported to be between 72% and 93%. For the high-performance athlete with an acute Jones fracture, early intramedullary-screw fixation is an accepted treatment option. Nonacute diaphyseal stress fractures of the proximal fifth metatarsal and Jones fractures that develop into delayed unions and nonunions can both be managed with operative fixation with either closed axial intramedullary-screw fixation or autogenous corticocancellous grafting. Early results with the use of electrical stimulation are promising; however, prospective studies are needed to better define the role of this modality in managing these injuries.