Screw Position Following Percutaneous Versus Mini-Open Intramedullary Retrograde Screw Fixation of Metacarpal Fractures

BACKGROUND

Metacarpal fracture fixation using the retrograde intramedullary screw technique can be performed through two different approaches. The mini-open approach requires greater soft tissue dissection but allows for direct visualization of the metacarpal head compared with the percutaneous approach. Our aim was to determine which approach resulted in optimal screw position.

METHODS

Eighty-one consecutive patients that underwent intramedullary screw fixation for metacarpal fractures from 2016 to 2021 were identified. Patients were treated by 4 fellowship-trained orthopedic hand surgeons who employed the mini-open or percutaneous approach. Postoperative radiographs were reviewed for screw position.

RESULTS

A total of 81 patients (41 mini-open, 40 percutaneous) were included in this study. There were no significant differences between the two groups in age, sex, hand dominance, or affected digit. Postoperative screw position at first postoperative visit was not significantly different between the two groups on anteroposterior or lateral radiographs.

CONCLUSION

Postoperative screw position is not significantly different between the mini-open and percutaneous approaches for intramedullary screw fixation of metacarpal fractures.

LEVEL OF EVIDENCE

Level III, therapeutic.

Dorsal Plating, Lateral Plating, and Intramedullary Screw Fixation of Extra-Articular Proximal Phalangeal Fractures: A Cadaveric Biomechanical Comparison

PURPOSE

To provide a biomechanical comparison of dorsal plating, lateral plating and intramedullary screw [IMS] fixation for extra-articular proximal phalangeal fractures.

METHODS

Midshaft osteotomies were performed on 36 cadaveric proximal phalanges. The phalanges were fixed by dorsal plating, lateral plating or IMS fixation, and subjected to a four-point bending force. Force was applied to achieve displacement of 1 mm/s, until construct failure or to a maximum of 10 mm of displacement. Clinical failure was defined as 2 mm of displacement, and force required to result in 1 mm and 2 mm of displacement was recorded, as was mode of failure.

RESULTS

Dorsal plating [127.5 N ± 52.6; 46.51-229.17] and lateral plating [77.1 N ± 25.1; 48.3-113.8] required significantly greater force to achieve 1 mm of displacement when compared to IMS [41.2 N ± 12.4; 20.6-62.3]. Dorsal plating [339.2 N ± 91.8; 158.5-538.6] required significantly greater force than lateral plating [154.5 N ± 33.8; 99.0 -204.4] and intramedullary screw fixation [110.0 ± 38.6; 51.1-189.3] to result in 2 mm of displacement. Lateral and dorsal plating constructs failed through plate bending, screw cut-out or plate failure, whilst IMS failed via implant deformity. All three constructs required greater force to result in even 1 mm of displacement than what is likely subjected through rehabilitation via active motion.

CONCLUSIONS

Lateral plating and IMS fixation offer sufficient stiffness to withstand the likely forces subjected via early active motion without displacement.

CLINICAL RELEVANCE

Dorsal plating required significantly greater force than lateral plating and intramedullary screw fixation to achieve 1 mm of displacement when used in extra-articular proximal phalangeal fractures in an in vitro setting. However, all three modalities confer enough stability to likely withstand the forces associated with active range of motion.

Metacarpal Shortening with Intramedullary Screw Fixation: A Cadaveric Study

Background  Intramedullary screw fixation is a commonly used technique for the management of metacarpal fractures. However, compression across the fracture site can lead to unintentional shortening of the metacarpal. Questions/Purposes  Our aim was to evaluate the risk of overshortening with differing intramedullary device designs for fixation of metacarpals. Methods  The small finger metacarpal of nine fresh-frozen cadavers were included. A metacarpal neck fracture was simulated with a 5-mm osteotomy. Three different intramedullary screw designs were compared. Each screw was placed in a retrograde fashion into the intramedullary canal and the amount of shortening measured. Screws were reversed and the number of reverse turns with the screwdriver needed to release overshortening were measured. Results  The average shortening at the osteotomy site was 2.5 mm. The mean shortening was 80%, 58%, and 12% for the partially threaded screw, fully threaded screw, and threaded nail, respectively. The mean differences of the distance shortened were statistically significant for the threaded nail compared with the partially and fully threaded screws. The partially threaded screw had the most shortening, while the threaded nail provided the least amount of shortening. When the screws were reversed, the screws did not disengage until the screw was fully removed from the osteotomy site. Conclusion  The fully threaded nail demonstrates less shortening and possibly minimizes overshortening of fractures compared with partially threaded and fully threaded screw designs. Overshortening cannot be corrected by unscrewing the screw unless completely removed from the distal fragment. Clinical Relevance  Orthopaedic surgeons may select intermedullary screws based on the design that is suited for the particular metacarpal fracture pattern.

Extensor Tendon Integrity After Percutaneous Placement of Intramedullary Metacarpal Screws: A Cadaveric Study

BACKGROUND

Intramedullary implants are an increasingly common method for fixation of metacarpal fractures. Numerous techniques for instrumentation have been described with varied consideration for the risk of extensor tendon injury. The current cadaveric study evaluates the prevalence and degree of extensor tendon injury and compares percutaneous approaches with different drilling techniques.

METHODS

Ninety-six metacarpals (thumbs excluded) from 24 fresh-frozen cadaveric upper extremities were used to compare 2 percutaneous approaches and 2 drilling techniques. This resulted in 4 subgroups available for comparison: oscillate to bone (OB), forward to bone (FB), oscillating through the skin (OS), and forward through the skin (FS). After instrumentation, the extensor tendons were dissected and disruption was characterized. The main outcome measures were tendon "hit rate" and relative extensor tendon defect width.

RESULTS

Tendon hit rate was significantly higher in the long finger (LF), that is, 79.2%, compared with other metacarpals: index finger, 20.8%; ring finger, 12.5%; and small finger 25%. The mean relative tendon disruption was significantly less in the OB group (16.05%) compared with the other groups: FB (31.84%), FS (31.50%), and OS (29.85%).

CONCLUSION

Retrograde intramedullary screw fixation of metacarpal fractures can be performed using percutaneous approaches without a significant disruption of the extensor mechanism. Instrumentation through a longitudinal stab incision down to the metacarpal head and the use of drill oscillation minimize injury to the extensor tendons. The LF extensor tendon is most at risk with retrograde intramedullary implant placement.

Metacarpal fractures

Metacarpal fractures are common and can be functionally disabling. The majority are managed non-operatively. When surgical intervention is indicated, various methods of fixation are available with the utility of each being based on injury pattern, patient function and surgeon preference. Early mobilization, especially in case of open reduction and internal fixation, is a critical component of treatment to prevent stiffness and restore function. When possible, a fixation construct that can withstand the applied forces of early postoperative motion is chosen. We provide an updated description for diagnosis, treatment options and operative fixation for metacarpal fractures.

Short-Term Outcomes of Jones-Specific Implant Versus Intramedullary Screw and Plate Fixation for Proximal Fifth Metatarsal Fractures

Although intramedullary screw fixation is commonly performed for proximal fifth metatarsal fractures, high rates of nonunion, refracture, and hardware prominence have been reported. The Jones Specific Implant (JSI) is a novel surgical implant which contours to the native curvature of the fifth metatarsal allowing for a more anatomic fixation. The purpose of this study was to compare short-term complication rates and outcomes of patients treated with the JSI to other fixation types such as plates and intramedullary screws. Electronic records were queried for adult patients with proximal fifth metatarsal fractures who underwent primary fixation from 2010 to 2021. All patients were treated by a foot and ankle fellowship-trained surgeon with intramedullary screws, plates, or JSI (Arthrex Inc., Naples, FL). Visual analog scale (VAS) and the American Orthopedic Foot and Ankle Score (AOFAS) were recorded and compared using univariate statistics. Eighty-five patients underwent fixation using intramedullary screw (n = 51, 60%), plate (n = 22, 25.9%), or JSI (n = 12, 14.1%) with a mean follow-up of 11.1 ± 14.6 months. The total cohort demonstrated a significant improvement in VAS pain (p < .0001) as well as AOFAS (p < .0001) scores. When comparing the cohort treated with JSI and the cohort treated with all other types of fixation, there were no significant differences in postoperative VAS or AOFAS scores. Only 3 complications, one with JSI (3.5%) required removal of the symptomatic hardware. The JSI is a novel treatment for proximal fifth metatarsal fractures, with similar early outcomes and complication rates when compared with intramedullary screw and plate fixation.

Evaluation of Intramedullary Olecranon Screw Fixation for Simple Olecranon Fractures: A Biomechanical Study

PURPOSE

The purpose of this study was to biomechanically evaluate the stability of the 6.5 mm intramedullary (IM) olecranon screw compared to locking compression plate fixation for Orthopedic Trauma Association/AO Foundation (OTA/AO) 2U1B1 olecranon fractures under cyclic range of motion of the elbow.

METHODS

Twenty paired elbows were randomized to either IM olecranon screw or locking compression plate fixation of a simulated OTA/AO 2U1B1 fracture. Pullout strength was tested by increasing force applied to the triceps and proximal fragment. Fracture gap displacement was measured using differential variable reluctance transducers as the elbow was cycled through a 135° arc of motion using a servohydraulic testing system.

RESULTS

Analysis of variance revealed significant interaction between group and load on fracture distraction after the 500th cycle in three settings: between the plate at 5-pound load and screw at 35-pound load, the screw at 5-pound load and screw at 35-pound load, and between the plate at 15-pound load and screw at 35-pound load. The difference in the rate of failure between plate (2 of 80 samples) and screw (4 of 80 samples) was not statistically significant.

CONCLUSIONS

For OTA/AO 2U1B1 olecranon fractures, a single 6.5 mm IM olecranon screw demonstrated similar stability when compared to the locking compression plates throughout range of motion testing.

CLINICAL RELEVANCE

From a biomechanical perspective, 6.5 mm IM screws and locking compression plates have similar ability to maintain fracture reduction following simulated elbow range of motion exercises in OTA/AO 2U1B1 fractures, giving surgeons another option in the management of these fractures.

Intra-Articular Antegrade Intramedullary Screw Fixation for Proximal Phalanx Fractures: Impact of Articular Surface Defects on Joint Contact Pressures

BACKGROUND

Intramedullary headless screw fixation is increasingly used for fixation of proximal phalanx fractures. However, the impact of screw entry defects on joint contact pressures is not well defined and may have implications for arthrosis. The objective of this cadaveric biomechanical study was to assess joint contact pressures at the metacarpophalangeal (MCP) joint before and after passage of 2 sizes of antegrade intramedullary fixation.

METHODS

Seven fresh frozen cadaver specimens without arthritis or deformity were included in this study. Antegrade intramedullary screw fixation of proximal phalanx fracture was simulated using an intra-articular technique. Flexible pressure sensors were inserted into the MCP joints and cyclic loading was performed. Peak contact pressures were determined and averaged across loading cycles for each finger in the native state, with 2.4- and 3.5-mm drill defects in line with the medullary canal.

RESULTS

Peak pressure increased with the size of the drill hole defect. Contact pressure increases were greater in extension, with peak contact pressures increased by 24% for the 2.4-mm defect and 52% for the 3.5-mm defect. Increase in peak contact pressure was statistically significant with a 3.5-mm articular defect. Contact pressures were not consistently increased for the 2.4-mm defect. Testing in flexion of 45° resulted in reduced contact pressure for these defects.

CONCLUSIONS

Our study demonstrates that antegrade intramedullary fixation of proximal phalanx fractures can increase MCP joint peak contact pressures, particularly in an extended joint position. Effect increases with defect size. This has implications for the management of proximal phalanx fractures using this technique.

Cost Comparison of Kirschner Wire Versus Intramedullary Screw Fixation of Metacarpal and Phalangeal Fractures

BACKGROUND

Intramedullary screw fixation is a relatively new technique for fixation of metacarpal and phalangeal fractures. The objective of this study was to compare health care-associated costs and outcomes for intramedullary screw versus Kirschner wire (K-wire) fixation of hand fractures.

METHODS

A retrospective review of patients undergoing intramedullary screw fixation of hand fractures at a single center during 2016-2019 inclusive was conducted. Health care-associated costs were compared with age-matched and fracture pattern-matched controls who underwent K-wire fixation.

RESULTS

Fifty patients met the study inclusion criteria, incorporating 62 fractures (29 K-wire, 33 intramedullary screw fixation). The median age was 34.6 years (18.0-90.1 years). There was no significant difference in primary operative costs (£1130.4 ± £162.7 for K-wire vs £1087.0 ± £104.2 for intramedullary screw), outpatient follow-up costs (£958.7 ± £149.4 for K-wire vs £782.4 ± £143.8 for intramedullary screw), or total health care-associated costs (£2089.1 ± £209.0 for K-wire vs £1869.4 ± £195.3 for intramedullary screw). However, follow-up costs were significantly lower for the uncomplicated intramedullary screw cohort (£847.1 ± £109.1 for K-wire vs £657.5 ± £130.8 for intramedullary screw, P = .05). Subgroup analysis also revealed that overall costs were significantly higher for buried K-wire techniques. Complication rates, time to return to active work, and Disabilities of the Arm, Shoulder, and Hand scores were similar.

CONCLUSIONS

This study identified significantly lower outpatient follow-up costs for uncomplicated intramedullary screw fixation of hand fractures compared with K-wires, along with a trend toward lower overall health care-associated costs. In addition, buried K-wire techniques were also found to carry a significantly higher financial burden. Higher powered prospective studies are required to determine indirect costs.

Intramedullary Metacarpal Fracture Fixation: A Biomechanical Study of Screw Diameter and Comparison With Intramedullary Wire Stabilization

PURPOSE

Interest in intramedullary metacarpal fracture fixation (IMFF) with screws is increasing. However, the optimal screw diameter for fracture fixation is not yet established. In theory, larger screws should be more stable, but there is concern about long-term sequelae of larger metacarpal head defects and extensor mechanism injury created during insertion as well as implant cost. Therefore, the purpose of this study was to compare different diameter screws for IMFF to a popular and more cost-effective alternative of intramedullary wiring.

METHODS

Thirty-two cadaveric metacarpals were used in a transverse metacarpal shaft fracture model. Treatment groups consisted of IMFF with 3.0 × 60 mm, 3.5 x 60 mm, and 4.5 x 60 mm screws as well as 4 1.1-mm intramedullary wires. Cyclic cantilever bending was performed with the metacarpals mounted at 45° to simulate physiologic loading. Cyclical loading at 10, 20, and 30 N was performed to determine fracture displacement, stiffness, and ultimate force.

RESULTS

At 10, 20, and 30 N of cyclical loading, all screw diameters tested provided similar stability as measured by fracture displacement and were superior to the wire group. However, ultimate force under load to failure testing was similar between the 3.5- and 4.5-mm screws and superior to 3.0-mm screws and wires.

CONCLUSIONS

For IMFF, 3.0, 3.5, and 4.5-mm diameter screws provide adequate stability for early active motion and are superior to wires. When comparing the different screw diameters, 3.5- and 4.5-mm diameter screws offer similar construct stability and strength superior to the 3.0-mm diameter screw. Therefore, to minimize metacarpal head morbidity, smaller screw diameters may be preferable.

CLINICAL RELEVANCE

This study suggests that IMFF with screws is biomechanically superior to wires in cantilever bending strength in the transverse fracture model. However, smaller screws may be sufficient to permit early active motion while minimizing metacarpal head morbidity.

Complications Following Intramedullary Screw Fixation for Metacarpal Fractures: A Systematic Review

PURPOSE

There has been a recent increase in the use of intramedullary screws (IMS) for the surgical treatment of metacarpal fractures. While IMS fixation has been shown to produce excellent functional outcomes, postoperative complications have yet to be fully explored in a comprehensive way. This systematic review quantified the incidence, treatment, and results of complications following IMS fixation for metacarpal fractures.

METHODS

A systematic review was performed using PubMed, Cochrane Central, EBSCO, and EMBASE databases. All clinical studies that documented IMS complications following metacarpal fracture fixation were included. Descriptive statistics were analyzed for all available data.

RESULTS

Twenty-six studies were included: 2 randomized trials, 4 cohort studies, 19 case series, and 1 case report. Among the 1,014 fractures studied, 47 complications were reported across all studies (4.6%). Stiffness was the most common, followed by extension lag, loss of reduction, shortening, and complex regional pain syndrome. Other complications included screw fracture, bending, and migration; early-onset arthrosis; infection; tendon adhesion; hypertrophic scar; hematoma; and nickel allergy. Eighteen of the 47 (38%) patients with complications underwent revision surgery.

CONCLUSIONS

Complications following IMS fixation of metacarpal fractures are relatively uncommon.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

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 Compression Screw Fixation of Proximal Phalangeal Fractures: A Systematic Literature Review

Proximal phalangeal fractures have traditionally been fixed via either Kirschner wires or dorsal plating. Concerns regarding lack of compression and potential for infection with wire fixation, and adhesion formation and stiffness with plating, have lead to alternative fixation methods, such as intramedullary screw fixation. However, the literature regarding this modality is limited. Methods: A systematic review was performed to review the literature regarding intramedullary screw fixation for proximal phalangeal fractures. English language studies that reported original data and commented on at least one postoperative measure of function were eligible for inclusion. 4 studies were eligible for inclusion, with a further 3 studies assessing proximal and middle phalanges analysed separately. Total active motion was greater than 240° in all proximal phalangeal studies; mean post-operative DASH was 3.62. 6% of patients sustained a major complication. Intramedullary screw fixation of proximal phalangeal fractures is safe, providing stable fixation to allow early motion.

Biomechanical Analysis of Conventional Partially Threaded Screws Versus Headless Compression Screws in Proximal Fifth Metatarsal (Jones) Fracture Fixation

BACKGROUND

Intramedullary screw fixation of Jones fractures using partially threaded screws is a common method of fixation for these injuries, but refracture continues to be a problem. Various other fixation strategies, such as headless compression screws, plantar plating, and tension-band wiring. have been developed to mitigate these issues. Biomechanical studies with regard to these other fixation strategies are limited. Herein, we investigate the compression strength and angular stiffness of Jones fractures fixed with Herbert-style headless compression screws.

METHODS

Jones fractures were created in 10 fresh-frozen pairs of cadaveric fifth metatarsals. A bone from each pair was instrumented with either a conventional, partially threaded screw 5.0 or 6.5 mm in diameter, or a headless compression screw 5.0 or 7.0 mm in diameter. Sizes were determined via sequential tapping until a snug fit was obtained. Each metatarsal was stressed via cantilever bending over 1000 cycles. We monitored compression and displacement throughout.

RESULTS

Headless compression screws achieved a significantly higher amount of stiffness than conventional, partially threaded screws (P = 0.005). There was no statistically significant difference with respect to compression.

CONCLUSION

In a cadaveric model, headless compression screws achieved a greater amount of fracture stiffness versus conventional, partially threaded screws.Levels of Evidence: Therapeutic, Level V: Biomechanical.

In vitro Biomechanical Analysis of Proximal Phalangeal Osteotomy Fixation

Background  Corrective osteotomies of the proximal phalanx are typically stabilized with plate and screws. Although intramedullary headless screws form an alternative fixation method in the treatment of acute phalangeal fractures, reports about fixation of opening wedge corrective osteotomies with these implants are lacking. Objective  The goal of the present study was to biomechanically compare the failure force of both fixation methods for this specific indication. Methods  Twenty-four cadaver phalanges were equally distributed between apex volar and apex lateral opening wedge osteotomy groups. In each group, half of the osteotomies were fixed with a 1.3-mm dorsal locking plate, the other half with a 2.4-mm intramedullary headless screw. A three-point bending test was performed. Results  The mean maximal failure force after apex lateral osteotomy was 178.4 N for the plate-screw construct and 144.0 N after intramedullary headless screw fixation. After apex volar osteotomy, mean maximal force was 237.6 N in the plate-screw group and 160.9 N in the intramedullary headless screw group. Mean stiffness after apex lateral osteotomy was 63.3 N/mm in the plate-screw group, and 55.9 N/mm in the intramedullary headless screw group. Mean stiffness after apex volar osteotomy was 197.5 N/mm and 60.0 N/mm for the plate-screw and intramedullary headless screw group, respectively. Conclusion  For apex volar osteotomies, dorsally applied angular stable plate and screws provide significantly stronger fixation than intramedullary headless screws. For apex lateral osteotomies, fixation force is comparable. Clinical relevance  These data are useful when considering fixation of opening wedge osteotomies with intramedullary screws.

The Effect of Intra-carpal Kirschner Wire Augmentation in Screw Fixation of Scaphoid - A Retrospective Cohort Study

Introduction:

Scaphoid fractures are most often treated with a single headless compression screw. However, intercarpal Kirschner wire (K-wire) might be added to improve stability and fracture outcomes. This study will determine if there is a difference in treatment outcome (union rate and time to union) between scaphoid fracture fixations using a single headless compression screw with and without augmentation using a intracarpal intramedullary K-wire.

Material and Methods:

We conducted a retrospective review of patients who underwent surgery for isolated scaphoid fractures over a 15 years period from December 2000 to December 2015. Only patients who underwent open surgery with bone grafting were included. They were divided into a group treated with a single screw fixation, and another group treated with screw and K-wire fixations.

Results:

Forty-four (58.7%) patients had single screw fixation and 31 (41.3%) had screw augmented with K-wire fixation. The overall union rate was 88.0%, with an overall mean time to union of 5.3 months. There was no difference in union rate (p=0.84) and time to union (p=0.66) between the single screw group and combined screw and K-wire group. Univariate analysis found that older age (t=-2.11, p=0.04) had a significant effect on union rate. Regression model showed that age had a significant effect on months to union.

Conclusion:

In open fixation of scaphoid fractures with compression screw and bone grafting, union rate and time to union is comparable whether or not screw fixation was augmented with an intracarpal K-wire. There was no increased risk of complications associated with augmented screw. Age of patient affected time to union and union rate.

Intramedullary screw fixation for metacarpal shaft fractures: a biomechanical human cadaver study

Intramedullary cannulated compression screws have been introduced for the fixation of unstable metacarpal fractures. In the present study, this technique was compared with dorsal compression plating to evaluate its biomechanical performance in stabilizing metacarpal shaft fractures. In a first set of experiments, the biomechanical characteristics of the screws were analysed in an artificial bone model. In subsequent experiments, midshaft osteotomies were performed in human cadaver metacarpals, followed by plating or intramedullary screw osteosynthesis. The metacarpals were tested to failure in cantilever bending, following a stepwise increasing cyclic loading protocol. We found a significantly lower load at failure and a significantly lower number of cycles to failure in the intramedullary screw group, but both methods offered sufficient stability under these loads. With reference to published loads on the metacarpals during use of the hand, we conclude that intramedullary osteosynthesis yields sufficient strength and stiffness for early active motion. A difference in its fixation stability is noted compared with plate fixation, which may not be clinically relevant.

Evaluation of Two Types of Intramedullary Jones Fracture Fixation in a Cyclic and Ultimate Load Model

Implant choice is a matter of concern in athletes and active patients who sustain a Jones fracture because they are prone to failure including non-union, screw failure, and refracture. The aim of this study was to compare the biomechanical behavior of a Jones fracture-specific screw (JFXS) with a cannulated headless compression screw (HCS) in a simulated partial weight-bearing and ultimate load Jones fracture fixation model. Ten matched pairs of human anatomical specimens underwent Jones fracture creation and consecutive intramedullary stabilization with a solid JFXS or a cannulated HCS. The bone mineral density was assessed prior to testing. Cyclic plantar to dorsal loading was applied for 1000 cycles, followed by load to failure testing. Angulation was measured by an opto-electronic motion capture system and mode of failure classification was determined by video analysis. Paired analysis showed no statistically significant difference between both screw constructs. Ultimate load reached 236.9 ± 107.8 N in the JFXS group compared with 210.8 ± 150.7 N in the HCS group (p = 0.429). The bone mineral density correlated positive with the pooled ultimate load (R = 0.580, p = 0.007) for all constructs and negatively with angulation (R = -0.680, p = 0.002) throughout cyclic loading. Solid fracture-specific and cannulated headless compression screws provide equal ultimate loads and stiffness for Jones fracture fixation. A low bone mineral density significantly impairs the construct stability and the ultimate load of both intramedullary screw constructs. © 2019 The Authors. Journal of Orthopaedic Research ® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society J Orthop Res 38:911-917, 2020.

Intramedullary Screw and Kirschner Wire Fixation for Unstable Scaphoid Nonunion

Surgical treatment of scaphoid nonunion is not always successful, often requiring stabilization and bone grafting to achieve healing. Even after intramedullary screw fixation, residual instability may still hinder union. The purpose of this study was to describe the addition of Kirschner wires (KWs) through the capitate and the lunate to supplement an intramedullary screw for temporary enhanced stability, possibly improving healing of unstable fractures. A case-control study reviewing 25 cases with addition of KWs and 19 controls was performed. Demographic and fracture information, time to diagnosis, and healing time were documented. We found no differences in population characteristics, fracture characteristics, or outcome measures between patients treated with this method and those treated with a screw alone. We had no complications related to the addition of KWs. Preoperative lunate type and scapholunate gapping was suggestive but not significantly associated with KW insertion. Addition of KWs is safe and may be considered in scaphoid nonunion in the presence of intraoperative suboptimal stability. Intraoperative stability may possibly be inferred by reviewing preoperative radiographs for signs of instability.

Biomechanical Comparison of Intramedullary Screw Versus Low-Profile Plate Fixation of a Jones Fracture

BACKGROUND

Intramedullary screw fixation of fifth metatarsal Jones fractures often produces satisfactory results, however, nonunion and refracture rates are not negligible. The low-profile "hook" plate is an alternative fixation method that has been promoted to offer improved rotational control at the fracture site, but this remains to be proven. The purpose of this study was to document biomechanical performance differences between this type of plate and a contemporary solid, dual-pitch intramedullary screw in a cadaveric Jones fracture model.

METHODS

Simulated Jones fractures were created in 8 matched pairs of fresh-frozen cadaveric fifth metatarsals. One bone from each pair was stabilized using an intramedullary TriMed Jones Screw and the other using a TriMed Jones Fracture Plate (TriMed, Inc, Santa Clarita, CA). Controlled bending and torsional loads were applied. Bending stiffness and fracture site angulation, as well as torsional stiffness, peak torque, and fracture site rotation were quantified and compared.

RESULTS

Intramedullary screw fixation demonstrated greater bending stiffness and less fracture site angulation than plate fixation during plantar-to-dorsal and lateral-to-medial bending. Torsional stiffness of screw-fixed metatarsals exceeded that of plate-fixed bones at initial loading; however, as rotation progressed, the plate resisted torque better than the screw. No difference in peak torque was demonstrable between fixation methods, but it was reached earlier in specimens fixed with screws and later in those fixed with plates as rotation progressed.

CONCLUSION

In this cadaveric Jones fracture model, intramedullary screw fixation demonstrated bending stiffness and resistance to early torsional loading that was superior to that offered by plate fixation.

CLINICAL RELEVANCE

Although low-profile "hook" plates offer an alternative for fixation of fifth metatarsal Jones fractures, intramedullary screw fixation may provide better resistance to bending and initiation of fracture site rotation. The influence of these mechanical characteristics on fracture healing is unknown, and further clinical investigation is warranted.

Comparison of Hallux Interphalangeal Joint Arthrodesis Fixation Techniques: A Retrospective Multicenter Study

Few studies have investigated the complications that occur after hallux interphalangeal joint arthrodesis. The present study evaluated complications in 152 patients aged 18 to 80 years from 2005 to 2012 from 4 different academic institutions after hallux interphalangeal joint arthrodesis. Overall, 65.8% of the patients had ≥1 complication. Infections occurred in 16.5%, dehiscence in 12.5%, and reoperations in 27.0%. The clinical nonunion rate was ≥17.8%, and the radiographic nonunion rate was ≥13.8%. After logistic regression analysis, only the study site and peripheral neuropathy were associated with having ≥1 complication (p < .01 and p < .05, respectively). Single screw fixation compared with other fixation did not have a statistically significant influence on the postoperative complications. However, when fixation was expanded to 4 categories, single screw fixation had lower infection and reoperation rates than either crossed Kirschner wires or other fixation category but not compared with crossed screws on multivariate logistic regression analysis. Although additional studies are warranted, the findings from the present study might aid in both the prognosis of complications and the support of the use of a single screw over crossed Kirchner wire fixation in hallux interphalangeal joint arthrodesis.