[Finite element analysis of the stability of Mason type Ⅲ radial head fracture fixed with three cross-bridge headless compression screw and locking plate]

OBJECTIVE

To compare the biomechanical stability of three cross-bridge headless compression screws and locking plates in the fixation of Mason type Ⅲ radial head fractures by finite element method.

METHODS

Using reverse modeling technology, the radial CT data and internal fixation data of a healthy 25-year-old male were imported into the relevant software. Three-dimensional finite element model of 3 cross-bridge headless compression screws and locking plates for MasonⅢ radial head fractures were established, and the radial head was loaded with 100 N axial loading. The maximum displacement, maximum Von Mises stress and stress distribution of the two groups were compared.

RESULTS

The maximum displacements of the three cross-bridge screws group and locking plate group were 0.069 mm and 0.087 mm respectively, and the Von Mises stress peaks were 18.59 MPa and 31.85 MPa respectively. The stress distribution of the three screws group was more uniform.

CONCLUSION

Both internal fixation methods can provide good fixation effect. CoMPared with the locking plate fixation method, the 3 cross-bridge headless compression screws fixation is more stable and the stress distribution is more uniform.

Unusual case report of concomitant lunate and scaphoid fractures without associated dislocation in a 16-year-old male

INTRODUCTION AND IMPORTANCE

Lunate fractures without associated dislocations are rare injuries, combination scaphoid-lunate fractures without an associated dislocation are even more rare of which few are reported in the literature.

CASE PRESENTATION

This case report describes a 16-year-old otherwise healthy male with ipsilateral scaphoid and lunate fractures after punching a goalpost with his left hand, for which he had surgical management. This patient had a successful treatment with two headless compression screws through a single extended carpal tunnel approach. Surgery was performed within two weeks of injury after initially immobilized with a thumb spica splint. The postoperative period was complicated by noncompliance with weight-bearing status and missed three-month followup. However, by six months, subsequent visits demonstrated radiographic and clinical healing as well as full wrist range of motion without any other sequelae.

CLINICAL DISCUSSION

This case offers more evidence regarding this rare injury. Lunate fractures and scaphoid fractures can both be treated with open reduction and internal fixation using headless compression screws, however little evidence exists when it comes to treating them in combination.

CONCLUSION

The use of headless compression screws through a single extended carpal tunnel approach led to clinical and radiographic healing in a 16 year-old-male with combined scaphoid and lunate fractures at 6 month follow up.

Double screw versus angular stable plate fixation of scaphoid waist nonunions in combination with intraoperative extracorporeal shockwave therapy (ESWT)

INTRODUCTION

Over the past years, different fixation techniques focused on rotational stability in order to increase stability and stimulate union rates. Additionally, extracorporeal shockwave therapy (ESWT) has gained importance in the treatment of delayed and nonunions. Purpose of this study was to compare the radiological and clinical outcome of two headless compression screws (HCS) and plate fixation in scaphoid nonunions, in combination with intraoperative high energy ESWT.

MATERIALS AND METHODS

Thirty-eight patients with scaphoid nonunions were treated by using a nonvascularized bone graft from the iliac crest and stabilization with either two HCS or a volar angular stable scaphoid plate. All patients received one ESWT session with 3000 impulses and energy flux per pulse of 0.41 mJ/mm² intraoperatively. Clinical assessment included range of motion (ROM), pain according to the Visual Analog Scale (VAS), grip strength, disability of the Arm Shoulder and Hand Score, Patient-Rated Wrist Evaluation Score, Michigan Hand Outcomes Questionnaire and modified Green O'Brien (Mayo) Wrist Score. To confirm union, a CT scan of the wrist was performed.

RESULTS

Thirty-two patients returned for clinical and radiological examination. Out of these, 29 (91%) showed bony union. All patients treated with two HCS compared to 16 out of 19 (84%) patients treated by plate showed bony union on the CT scans. The difference was not statistically significant. However, at a mean follow-up interval of 34 months, no significant differences could be found in ROM, pain, grip strength and patient-reported outcome measurements between the two HCS and plate group. Height-to-length ratio and capitolunate angle improved significantly in both groups compared to preoperative.

CONCLUSIONS

Scaphoid nonunion stabilization by using two HCS or angular stable volar plate fixation and intraoperative ESWT results in comparable high union rates and good functional outcome. Due to the higher rate for a secondary intervention (plate removal), HCS might be preferable as first choice, whereas the scaphoid plate fixation should be reserved for recalcitrant (substantial bone loss, humpback deformity or failed prior surgical intervention) scaphoid nonunions.

Arthroscopic treatment of unstable scaphoid fracture and nonunion with two headless compression screws and distal radius bone graft

BACKGROUND

The treatment of unstable scaphoid fracture and nonunion remains a challenging problem for hand surgeons. Minimally invasive treatment has become the preferred method of treatment.

PURPOSE

This study introduces the arthroscopic technique with two headless compression screws (HCS) fixation and distal radius bone grafting for the treatment of unstable scaphoid fracture and nonunion, aiming to evaluate its clinical and radiological outcomes.

METHODS

It was a retrospective study. From January 2019 to February 2021, a total of 23 patients were included in the current study. Among them, 13 patients with unstable scaphoid fracture underwent arthroscopic treatment with two HCS; 10 patients with scaphoid nonunion underwent arthroscopic treatment with two HCS and a distal radius bone graft. The range of motion of the wrist, visual analog scale (VAS), grip strength, the Modified Mayo Wrist Score (MMWS), the Patient-Rated Wrist Evaluation (PRWE) score, and the Disability of the Arm, Shoulder and Hand (DASH) score were collected at preoperatively and the final follow-up. A computed tomography scan of the wrist was performed on each patient to analyze for union and postoperative osteoarthritis during the follow-up period.

RESULTS

Significant improvement was only observed in wrist extension. Clinical outcomes including grip strength, VAS pain score, MMWS, PRWE score, and DASH score were significantly improved at the final follow-up. In the subgroup analysis, both patients stabilized with either two HCS or a distal radius bone graft and two HCS have improved clinical outcomes after surgery, respectively. All patients achieved union. No screw fixation failure occurred, and no other postoperative complication was observed in any of the patients.

CONCLUSIONS

The arthroscopic technique with two-HCS fixation and distal radius bone grafting is a reliable and effective technique for the treatment of unstable scaphoid fracture and nonunion, providing satisfactory union rates and clinical outcomes.

Clinical Results of Surgical Treatment for Comminuted Radial Head and Neck Fracture: Headless Compression Screws Versus Plate Fixation

Background

We surgically treated comminuted radial head and neck fractures using headless compression screws, including multiple screws for the radial head and a single oblique screw for the radial neck. This study aimed to compare the clinical and radiological results for comminuted radial head and neck fractures between surgery using headless compression screws with a single oblique screw for the radial neck, our new procedure, and a plate system precontoured to the proximal radius.

Methods

This retrospective study included 23 patients (11 and 12 in the screw and plate groups, respectively). The fractures were type 3 according to the Mason-Johnston classification modified by Broberg and Morrey. Clinical outcomes analyzed included the motion range of the elbow and forearm, Mayo Elbow Performance Score, and radiological assessments. In addition, postoperative complications were also investigated. The average follow-up was 18 months.

Results

The bone union was achieved in all the patients, and there were no significant differences in clinical outcomes and radiological assessments except forearm supination (p = 0.02). Furthermore, additional surgical procedures were performed in one and five patients in the screw and plate groups, respectively (p = 0.16). Posterior nerve palsy was observed in two patients in the plate group. Complications were observed in one and six patients in the screw and plate groups, respectively (p = 0.07).

Conclusion

Both surgical procedures achieved good clinical and radiological outcomes with bone and ligament injury repair. The screw group had a greater range of forearm supination than the plate group.

Radiological Outcomes of the Simplified Sauvé-Kapandji Procedure for Osteoarthritis of the Distal Radioulnar Joint

Background: We have been using a simplified Sauvé-Kapandji (SK) procedure using a headless compression screw for the treatment of osteoarthritis (OA) of the distal radio-ulnar joint (DRUJ). Unlike a standard SK procedure, the simplified SK procedure does not require exposure of the DRUJ to prepare the opposing surfaces of the sigmoid fossa and the ulnar head or any procedures to stabilise the proximal stump of the ulna. The aim of this study is to report the radiological outcomes of the simplified SK procedure. Methods: We retrospectively reviewed data of all patients who underwent a simplified SK procedure for osteoarthritis of the DRUJ at our hospital between October 2008 and September 2020 with a follow-up of at least 25 weeks. Baseline demographic and clinical characteristics were investigated. We also measured radiographic parameters and performed statistical analyses to evaluate the shelf-forming region, ulnar stump and deviation of the carpal region. Results: Our study included 10 patients with a mean follow-up of 52.3 weeks. There was no instance of complications such as nonunion of DRUJ arthrodesis, callus formation at ulnar pseudoarthrosis and painful instability at the proximal stump of the ulna. According to the Wilcoxon signed rank test, no radiographic parameters significantly changed during the follow-up period. There was a significant negative correlation between radioulnar width and the variation of ulnar translation index. Conclusions: All radiographic parameters were well maintained, at least during the short follow-up period. There was no instance of nonunion of DRUJ arthrodesis. The simplified SK with simple headless compression screw insertion may be a reliable method for treating OA of the DRUJ. Level of Evidence: Level IV (Therapeutic).

Distal interphalangeal joint arthrodesis with nonaxial multiple small screws: a biomechanical analysis with axial headless compression screw and clinical result of 15 consecutive cases

Background

The axial headless compression screw (AHCS) technique is a widely used method for distal interphalangeal joint (DIPJ) and thumb IPJ arthrodesis. However, it might not be suitable for cases over 10° flexion of fusion angle and extremely small-sized phalanx. Here, the authors describe the nonaxial multiple small screws (NMSS) technique, compare the mechanical strength of the NMSS technique with the AHCS technique, and suggest clinical outcomes of the NMSS technique.

Methods

DIPJ and thumb IPJ arthrodesis models were simulated in the 4th generation composite bone hand. Fixation with three 1.5 mm cortical screws (NMSS) or one HCS (AHCS) was performed in each pair of the phalanx. The bending stiffness and load to failure were tested in 10 pairs of each specimen, and the torsional stiffness and torque to failure were tested in seven pairs of each specimen. Moreover, 15 consecutive clinical DIPJ and thumb IPJ arthrodesis cases were reviewed retrospectively.

Results

The NMSS specimens showed significantly higher bending load to failure, torsional stiffness, and torque to failure than the AHCS specimens. All 15 arthrodesis cases were united without severe complications. The mean fusion angle was 16.3° for the nine cases of the flexed target position.

Conclusions

The NMSS technique showed biomechanical stability comparable to that of the AHCS technique in DIPJ and thumb IPJ arthrodesis. Thus, the NMSS technique could be used as a feasible option in DIPJ and thumb IPJ arthrodesis, especially when a small finger is indicated and a significant flexion angle is required.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05473-9.

Minimally Invasive Intramedullary Screw Versus Plate Fixation for Proximal Phalanx Fractures: A Biomechanical Study

PURPOSE

To compare the maximum interfragmentary displacement of short oblique proximal phalanx (P1) fractures fixed with an intramedullary headless compression screw (IMHCS) versus a plate-and-screws construct in a cadaveric model that generates finger motion via the flexor and extensor tendons of the fingers.

METHODS

We created a 30° oblique cut in 24 P1s of the index, middle, ring, and little fingers for 3 matched pairs of cadaveric hands. Twelve fractures were stabilized with an IMHCS using an antegrade, dorsal articular margin technique at the P1 base. The 12 matched-pair P1 fractures were stabilized with a radially placed 2.0-mm plate with 2 bicortical nonlocking screws on each side of the fracture. Hands were mounted to a frame allowing a computer-controlled, motor-driven, linear actuator powered movement of fingers via 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.

RESULTS

The observed mean displacement differences between IMHCS and plate-and-screws fixation was not statistically significant throughout all time points during the 2,000 cycles. A 2 one-sided test procedure for paired samples confirmed statistical equivalence in fracture displacement between fixation methods at the final 2,000-cycle time point.

CONCLUSIONS

The IMHCS provided biomechanical stability equivalent to plate-and-screws for short oblique P1 fractures at the 2,000-cycle mark in this cadaveric model.

CLINICAL RELEVANCE

Short oblique P1 fracture fixation with an IMHCS may provide adequate stability to withstand immediate postoperative active range of motion therapy.

Metacarpal shaft fixation: a biomechanical comparison of dorsal plating, lag screws, and headless compression screws

Background

Metacarpal shaft fractures are common and can be treated nonoperatively. Shortening, angulation, and rotational deformity are indications for surgical treatment. Various forms of treatment with advantages and disadvantages have been documented. The purpose of the study was to determine the stability of fracture fixation with intramedullary headless compression screws in two types of metacarpal shaft fractures and compare them to other common forms of rigid fixation: dorsal plating and lag screw fixation. It was hypothesized that headless compression screws would demonstrate a biomechanical stronger construct.

Methods

Five matched paired hands (age 60.9 ± 4.6 years), utilizing non-thumb metacarpals, were used for comparative fixation in two fracture types created by an osteotomy. In transverse diaphyseal fractures, fixation by headless compression screws (n = 7) and plating (n = 8) were compared. In long oblique diaphyseal fractures, headless compression screws (n = 8) were compared with plating (n = 8) and lag screws (n = 7). Testing was performed using an MTS frame producing an apex dorsal, three point bending force. Peak load to failure and stiffness were calculated from the load-displacement curve generated.

Results

For transverse fractures, headless compression screws had a significantly higher stiffness and peak load to failure, means 249.4 N/mm and 584.8 N, than plates, means 129.02 N/mm and 303.9 N (both p < 0.001). For long oblique fractures, stiffness and peak load to failure for headless compression screws were means 209 N/mm and 758.4 N, for plates 258.7 N/mm and 518.5 N, and for lag screws 172.18 N/mm and 234.11 N. There was significance in peak load to failure for headless compression screws vs plates (p = 0.023), headless compression screws vs lag screws (p < 0.001), and plates vs lag screws (p = 0.009). There was no significant difference in stiffness between groups.

Conclusion

Intramedullary fixation of diaphyseal metacarpal fractures with a headless compression screw provides excellent biomechanical stability. Coupled with lower risks for adverse effects, headless compression screws may be a preferable option for those requiring rapid return to sport or work.

Level of evidence

Basic Science Study, Biomechanics.

Peroneus brevis as source of instability in Jones fracture fixation

Purpose

Intramedullary screw fixation is currently considered the gold standard treatment for Jones fractures in the athlete. Besides biological factors (i.e., poor vascularization), mechanical instability induced by the pull of the peroneus brevis tendon (PBT) contributes to deficient Jones fracture healing. This biomechanical study aimed to simulate loads induced by the PBT at the fifth metatarsal and to compare the stability of two intramedullary screw constructs in a Jones fracture fixation model.

Methods

Jones fractures were created in 24 human paired specimens, and fixation was achieved with either a solid Jones fracture specific screw (JFXS) (Jones Screw; Arthrex Inc., Naples FL, USA) or a cannulated headless compression screw (HCS) (HCS; DePuySynthes, Solothurn, Switzerland). The PBT was fixed to a mechanical load frame by the use of a cryoclamp. Constructs were loaded in tension for 1000 cycles, followed by an ultimate load test. Construct failure was defined by exceeding 10° of dorsal angulation.

Results

Preliminary failure occurred more often in HCS constructs (33%) compared to JFXS constructs (0%) (P = 0.044). Mean tensile load to failure reached 123.8 ± 91.4 N in the JFXS group and 91.5 ± 62.2 N in the HCS group (P = 0.337). The mean slope of the load-displacement curve was 24.2 ± 10.4 N/mm for JFXS constructs and 24.7 ± 5.5 N/mm for HCS constructs, respectively (P = 0.887).

Conclusion

This is the first study evaluating the effect of PBT pull on the mechanical stability of Jones fracture fixation. Higher preliminary failure rates of HCS were found under cyclic loading conditions compared to JFXS.

Electronic supplementary material

The online version of this article (10.1007/s00264-020-04581-2) contains supplementary material, which is available to authorized users.

Fully threaded headless compression screw versus partially threaded cancellous lag screw in medial malleolus fractures: clinical and radiological outcomes

PURPOSE

The aim of this study was to evaluate the clinical and radiological results of medial malleolar fractures, which were treated with fully threaded headless compression screws and to compare the clinical and radiological results of this screws and partially threaded cancellous lag screws.

METHODS

Sixty-one patients who attended the final follow-up examination were included in the study. Group 1 comprised 29 patients applied with fully threaded headless compression screws and Group 2 comprised 32 patients with partially threaded cancellous lag screws. Radiological evaluation was made with standard radiographs. The clinical evaluations were applied using the AOFAS ankle hindfoot scale. Pain or sensitivity by touching over the medial malleolus was recorded and scored according to Visual Analog Scale.

RESULTS

No significant differences were determined between the groups with respect to age, gender, fracture type, follow-up time, bone union time and AOFAS scores. The medial sensitivity associated with implant irritation was significantly lower in Group 1. There was no need for removal of the fixation material in any patient of Group 1.

CONCLUSIONS

The results of this study showed satisfactory results in the two fixation techniques in medial malleolar fractures. However, the rates of medial sensitivity associated with implant irritation were lower in the group where fully threaded headless compression screws were used. Therefore, to prevent postoperative patient dissatisfaction caused by persistent medial sensitivity associated with implant irritation, despite successful surgical treatment, the primary choice may be fully threaded headless compression screws.

Comparison of compression screws used for mandible head fracture treatment-experimental study

OBJECTIVES

Compression screws that can fix a fracture of the condylar head of the mandible are available. Although typical titanium lag screws are generally used, a series of headless screws have been designed for this purpose. The "headless" advantage derived from the complete submergence of the screw in the bone after fixation is the lack of irritation of the lateral ligament of the temporo-mandibular joint by the screw head. The aim of this study is to compare the compression force of typically used lag screws with that of newly developed headless compression screws.

MATERIALS AND METHODS

This study tested five types of screws with a 14-mm length: 10 2.0-mm lag screws and 40 headless screws (four groups of equal size: 1.5-mm H screws, 1.8-mm H screws, 2.0-mm H screws, and 1.8-mm W screws). Two cuboid blocks of standardized polyurethane foam were fixed by one screw. The maximal compression force (F in N) and torque at maximal compression force (T in Ncm) were tested according to the guidelines of the American Society for Testing and Materials (ASTM F1839-08).

RESULTS

The test results were as follows: 2.0-mm lag screw: F = 211.5 ± 20.7 and T = 21.1 ± 1.6; 1.5-mm H screw: F = 47.2 ± 5.6 and T = 18.2 ± 1.1; 1.8-mm H screw: F = 95.5 ± 9.8 and T = 18.2 ± 1.1; 2.0-mm H screw: F = 145.1 ± 18.4 and T = 25.5 ± 1.5; and 1.8-mm W screw: F = 180.5 ± 8.7 and T = 26.4 ± 2.8. Each type of screw significantly differed from one another as far as compression forces (F) were considered (p < 0.05): the best is the lag screw contrary to the thinnest H screw which is the worst one. For all tested screws, the compression force depended on the torque (S curve relationship was revealed, p < 0.05) and screw diameter (a larger diameter yielded greater compression, p < 0.05).

CONCLUSIONS

The 8-mm headless screws featured only a small loss of compression ability compared to the titanium lag screws.

CLINICAL RELEVANCE

Headless screws are mechanically attractive fixation materials for condylar head fracture treatment.

A Comparative Study of Tensile Strength of Three Operative Fixation Techniques for Metacarpal Shaft Fractures in Adults: A Cadaver Study

Background

We sought to estimate the ultimate tensile strength after metacarpal shaft fracture repair in adults using three operative fixation methods: plate fixation, Kirschner wire (K-wire) fixation, and intramedullary headless compression screw fixation. We also compared the advantages and disadvantages of each operative technique.

Methods

We acquired 30 metacarpal bones from four Korean adult cadavers without trauma, operative history, or deformities. The 30 metacarpal bones were divided into ten groups consisting of three metacarpal bones each with matching sizes and lengths. They were fractured, reduced, and fixed with plate and screws, K-wires, or headless compression screws. We performed force testing, collected ultimate tensile strength data, and created a stress-strain graph.

Results

The ultimate tensile strength of ten groups according to the fixation method was as follows: late and screw fixation, 246.1 N (range, 175.3 to 452.4 N); K-wire fixation, 134.6 N (62.7 to 175.0 N); and intramedullary headless compression screw fixation, 181.2 N (119.2 to 211.7 N). The median tensile strength of each fixation method was significantly different. In addition, the post-hoc test showed significant difference between the plate and screw fixation and K-wire fixation, between the headless compression screw fixation and K-wire fixation, and between the headless compression screw fixation and plate and screw fixation.

Conclusions

The tensile strength median values decreased in the following order showing significant differences among the fixation methods: plate and screw fixation, headless compression screw fixation, K-wire fixation. Significant differences were also observed between the plate and screw fixation and K-wire fixation, between the headless compression screw fixation and K-wire fixation, and between the headless compression screw fixation and plate and screw fixation.

Treatment of scaphoid waist nonunion by one, two headless compression screws or plate with or without additional extracorporeal shockwave therapy

INTRODUCTION

Scaphoid nonunion remains challenging for hand surgeons. Several treatment options are available such as: non-vascularized or vascularized bone grafting, with or without additional stabilization. In the last few decades, extracorporeal shockwave therapy (ESWT) has become an established procedure for treating delayed and nonunions. Purpose of this retrospective follow-up study was (a) to investigate union rate and clinical outcome of the different implants [either one/two headless compression screws (HCS) or a plate] and (b) union rate and clinical outcome using only surgery, or a combination of surgery and ESWT.

MATERIALS AND METHODS

The study included 42 patients with scaphoid nonunions of the waist with a mean follow-up of 52 months. All patients received a non-vascularized bone graft from the iliac crest and stabilization was achieved by using one, two HCS or a plate. ESWT was performed with 3000 impulses, energy flux density per pulse 0.41 mJ/mm² within 2 weeks after surgery. Clinical assessment included range of motion (ROM), pain according to the Visual Analog Scale (VAS), grip strength, Disability of the Arm Shoulder and Hand Score, Patient-Rated Wrist Evaluation Score, Michigan Hand Outcomes Questionnaire and modified Green O'Brien (Mayo) Wrist Score. In addition, each patient had a CT scan of the wrist.

RESULTS

A total of 33/42 (79%) patients showed union at the follow-up investigation. Patients treated with additional ESWT showed bony healing in 21/26 (81%) and without ESWT in 12/16 (75%). Patients that were stabilized using one HCS showed bony healing in 6/10 (60%), with two HCS 10/12 (83%) and by plate 17/20 (85%). The ESWT group had a significantly lower pain score according to the VAS and better modified Green O'Brien (Mayo) Score. No differences could be found in respect of ROM, grip strength, functional outcome score depending of which stabilization method was used.

CONCLUSIONS

Stabilization of scaphoid waist nonunions with two HCS or plate showed higher union rates than a stabilization using only one HCS. In addition, ESWT combined with a nonvascularized bone graft from the iliac crest seems a suitable option for treating scaphoid nonunions.

A comparative study of the effect of drilling depth on generation of compressive force by headless compression screws using conical and cylindrical type of drill bit

Background

This study was conducted to measure the effect of different drilling depths on compression forces generated by two commonly used headless compression screws using the two different types of drill bit, the Acutrak® mini (conical type drill bit) and the Synthes 3.0 HCS® (cylindrical type drill bit).

Methods

A load cell was placed between two Sawbone blocks, which were 12 mm and 40 mm in thickness, respectively. After placing the guide pin into the center of the block, the drilling depth of the Acutrak® mini and Synthes HCS® screws ranged from 16 to 28 mm and 22 to 28 mm, respectively. The 24-mm screws were inserted and the compression force was measured immediately and at 30 min post-insertion.

Results

The Acutrak® mini generated greater compression force compared to the Synthes 3.0 HCS® when drilled to a depth of less than 24 mm. The compression force of the Acutrak® mini showed a strong inverse correlation with the drilling depth. There was no significant inverse correlation observed between the compression force of the Synthes HCS® and the drilling depth.

Conclusions

If the screw length and the drill depth are the same, the Synthes 3.0 HCS® (cylindrical type drill bit) is safer and easier to use as it has no change in the compression force even when over-drilling because the compression force of the two screws is similar. As for the Acutrak® mini (conical type drill bit), while it is technically demanding due to varying compression force according to the drill depth, it can be used in certain cases because it can give stronger compression force through under-drilling.

Does fully-threaded Headless Compression Screw provide a length-stable fixation in undisplaced femoral neck fractures?

OBJECTIVE

Femoral neck shortening is a common complication after surgical treatment for intracapsular femoral neck fractures. This study investigated whether fully-threaded Headless Compression Screw (FTHCS) can be a more length-stable implant than partially-threaded cannulated screw (PTCS) in reducing femoral neck shortening.

METHODS

A total of 50 patients with undisplaced femoral neck fractures (17 treated by internal fixation with three FTHCS, and 33 treated by three PTCS) from 2011 to 2014 were enrolled in this study. The radiography of the hips and medical records were reviewed for proximal femur geometry and complications.

RESULTS

Significant shortening of the femoral neck length until union were noted in both group (FTHCS group: -2.5 mm, p = 0.045; PTCS group: -2.4 mm, p = 0.011). There was no significant difference in the length of femoral neck shortening between groups (p = 0.855). Age was the only significant risk factor for >5 mm of femoral neck shortening (p = 0.041). The femoral neck-shaft angle tended to reduce and become more varus in both groups (FTHCS: -2.7°, SD = 4.5, p = 0.028; PTCS: -5.0°, SD = 8.3, p = 0.002), but the differences between groups were nonsignificant (p = 0.577). The complication rates were similar between FTHCS and PTCS (17.6% and 21.2%, p > 0.999).

CONCLUSION

The FTHCSs may be a substitute for PTCSs, but it cannot prevent femoral neck shortening and varus collapse after fracture fixation. Future studies should focus on how to preserve femoral neck length and hip function after femoral neck fractures.

Headless compression screw for horizontal medial malleolus fractures

BACKGROUND

Horizontal medial malleolus fractures are caused by the application of rotational force through the ankle joint in several orientations. Multiple techniques are available for the fixation of medial malleolar fractures.

METHODS

Horizontal medial malleolus osteotomies were performed in eighteen synthetic distal tibiae and randomized into two fixation groups: 1) two parallel unicortical cancellous screws or 2) two Acutrak 2 headless compression screws. Specimens were subjected to offset axial tension loading. Frontal plane interfragmentary motion was monitored.

FINDINGS

The headless compression group (1699 (SD 947) N/mm) had significantly greater proximal-distal stiffness than the unicortical group (668 (SD 298) N/mm), (P = 0.012). Similarly, the headless compression group (604 (SD 148) N/mm) had significantly greater medial-lateral stiffness than the unicortical group (281 (SD 152) N/mm), (P < 0.001). The force at 2 mm of lateral displacement was significantly greater in the headless compression group (955 (SD 79) N) compared to the unicortical group (679 (SD 198) N), (P = 0.003). At 2 mm of distal displacement, the mean force was higher in the headless compression group (1037 (SD 122) N) compared to the unicortical group (729 (SD 229) N), but the difference was not significant (P = 0.131).

INTERPRETATION

A headless compression screw construct was significantly stiffer in both the proximal-distal and medial-lateral directions, indicating greater resistance to both axial and shear loading. Additionally, they had significantly greater load at clinical failure based on lateral displacement. The low-profile design of the headless compression screw minimizes soft tissue irritation and reduces need for implant removal.

Effects of Removal and Reinsertion of Headless Compression Screws

PURPOSE

This study investigates the loss of compression when 3 commonly used headless compression screws are backed out (reversed), and assesses the ability to re-establish compression with screws of greater diameter.

METHODS

Two investigators tested 3 screw designs (Acutrak 2, Synthes HCS, Medartis SpeedTip CCS) in 2 diameters and lengths. Each design had 10 test cycles in a polyurethane foam bone model with compression recorded using a washer load cell. A 28-mm screw of the narrower diameter was inserted until 2 mm recessed and then reversed 30°, 60°, 90°, 180°, 270°, 360°, and 720°. After this the screw was removed completely and a 24-mm screw of greater diameter inserted until recessed 2 mm with the compressive force again recorded.

RESULTS

All screws showed an immediate, statistically significant loss of compression at 30° of reversing. The Acutrak 2 Micro screw demonstrated not only the greatest mean compressive force, but also the fastest compressive loss. Insertion of the shorter screw of greater diameter was associated with re-establishment of compression to levels comparable with the original screw.

CONCLUSIONS

This study reaffirms the importance of establishing the correct screw length before insertion due to the immediate loss of compression with reversal of these devices.

CLINICAL RELEVANCE

If a headless compression screw penetrates the far joint surface, the screw should be completely removed and replaced with a shorter screw of greater diameter.

Stabilization of scaphoid type B2 fractures with one or two headless compression screws

INTRODUCTION

Fractures of the scaphoid account for the most commonly injured carpal bone. Minimally displaced fractures of the waist will heal in 85-90% when using a below elbow cast. However, fractures with displacement have a higher risk for nonunion. Therefore, open reduction and fixation with headless compression screws (HCS) have become the preferred method of treatment. The aim of this study was to compare the radiological and clinical outcome of unstable scaphoid B2 type fractures, stabilized using one or two headless compression screws.

PATIENTS AND METHODS

A total of 47 unstable scaphoid B2 type fractures were included in this retrospective follow-up study. Twelve patients were not accessable and three refused to attend follow-up checks. Therefore, a total of 32 patients were included in this study with a mean follow-up interval of 43 (12-81) months. Twenty-two patients were treated using one HCS and ten with two HCS. Clinical assessment included range of motion (ROM), pain according to the visual analogue scale (VAS), grip strength, Disability of the Arm, Shoulder and Hand Score, Patient-Rated Wrist Evaluation Score, Michigan Hand Outcomes Questionnaire and modified Green O'Brien Wrist Score. The follow-up study on each patient included a CT-Scan of the wrist which was analyzed for union, osteoarthritis, dorsiflexed intercalated segment instability and humpback deformity.

RESULTS

Radiologically, 29/32 (91%) of the scaphoid B2 type fractures showed union, 10/10 (100%) in the two HCS group and 19/22 (86%) in the one HCS group (p < 0.05). No significant differences could be found in respect to ROM, grip strength, VAS and scores between the groups. Screw removal was necessary in two patients in the two HCS group and one in the one HCS group.

CONCLUSION

The unstable B2 type fractures of the scaphoid, when using two HCS without bone grafting is a safe method, shows a significantly higher union rate and equal clinical outcome compared to stabilization using only one HCS.

A Complicated Course of a Coronal Shear Fracture Type IV of the Distal Part of Humerus Resulting in Resurfacing Radiocapitellar Joint Replacement

Background:

Coronal shear fracture type IV of the distal part of humerus is a very rare injury with articular complexity potentially leading to posttraumatic osteoarthritis. One option for surgical treatment of advanced unicompartmental radiocapitellar osteoarthritis is resurfacing radiocapitellar joint replacement.

Method:

A 62-year- old female sustained a coronal shear fracture type IV of the distal part of left humerus that was primarily treated with open reduction and internal fixation using headless compression screws. Three years postoperatively, there was a migration of one screw into radiocapitellar joint that led to circular deep cartilage defect of radial head. Four years after ORIF, a distinctive radiocapitellar osteoarthritis has evolved leading to a resurfacing radiocapitellar joint replacement using the Lateral Resurfacing Elbow^TM (LRE) system.

Result:

At the 2-year follow-up after that procedure, there was an excellent subjective and functional outcome. Radiographically, no loosening or subsidence of implant without any signs of overstuffing could be found. The patient reported that she would have the same procedure again.

Conclusion:

The goal of unicompartmental radiocapitellar replacement is to obtain stability in elbow joint by avoiding cubitus valgus with subsequent instability of the distal radioulnar joint, and it does not alter the unaffected ulnohumeral joint. Additionally, the feature of the LRE^TM system is that the radial head is not excised, and so will receive the anatomical length of the overall radius articulating with the capitellum by preserving the annular ligament. In the literature only three publications could be found in which short-term results with the use of the LRE^TM system have been described. Hence, further studies are needed to validate this concept.

Non-structural cancellous bone graft and headless compression screw fixation for treatment of scaphoid waist non-union

PURPOSE

Scaphoid fracture commonly occurs around the mid-third of the scaphoid, and non-union of this fracture has several treatment options. The authors performed autologous cancellous bone graft from the iliac crest and headless compression screw fixation for the treatment of Mack-Lichtman type II scaphoid waist non-union. The purpose of this study was to determine whether this procedure was effective in achieving bony union and restoration of alignment.

METHODS

Medical records and radiographs of 30 patients who underwent cancellous bone graft and headless compression screw fixation for non-union of scaphoid waist fracture were retrospectively reviewed. There were 28 men and 2 women, with a mean age of 32.8 years (range: 21-63). The mean time to surgery was 10 months (range: 3-25) and mean follow-up was 37.5 months (range: 15-52). The authors analyzed bony union, lateral intrascaphoid angle, scapholunate angle, radiolunate angle and scaphoid length on radiographs and evaluated the Modified Mayo wrist score (MMWS) as a functional outcome.

RESULTS

Bony union was achieved in all cases. The lateral intrascaphoid angle improved from 40° to 32° (P<0.001). The scapholunate angle also improved from 61° to 56° (P=0.009). The radiolunate angle decreased from 8° to 4° (P=0.048) and scaphoid length increased from 22mm to 26mm (P<0.001) postoperatively. Wrist motion and MMWS improved significantly at last follow-up. However, there were no significant differences between scaphoid deformity correction angle and pre- to post-operative difference in MMWS.

CONCLUSIONS

Non-structural autologous cancellous bone graft from the iliac crest and headless screw fixation provided reliable results and can be one of the effective treatment options for patients with symptomatic Mack-Lichtman type II non-union in the mid-third of the scaphoid.

LEVEL OF EVIDENCE

Level III.

Pediatric conjoint Hoffa's fracture: An uncommon injury and review of literature

Coronal plane fracture of femoral condyles was first elaborated by Hoffa. These are difficult articular injuries, often described in adult skeleton and very rarely in pediatric age group. Conjoint variety with intact bone bridge between condyles in intercondylar notch area is rare. We report a conjoint variety of bicondylar Hoffa's fracture in a child which was surgically treated using headless compression screws along with a brief review of literature about fracture entity and complexities associated with it.

Rotational stability in screw-fixed scaphoid fractures compared to plate-fixed scaphoid fractures

BACKGROUND

The literature describes the treatment of scaphoid fractures comparing the volar and dorsal approaches, the advantages and disadvantages of percutaneous screw fixation, as well as the treatment of scaphoid nonunions using different types of cancellous or corticocancellous bone grafts. Yet, to date no studies are available comparing the outcome of rotational stability in screw-fixed scaphoid fractures to angular stable systems. The purpose of this study is to provide reliable data about rotational stability in stabilised scaphoid fractures and to gain information about the rigidity and the stability of the different types of fixation.

METHODS

Three groups of different stabilisation methods on standardised scaphoid B2 fractures were tested for rotational stability. Stabilisation was achieved using one or two cannulated compression screws (CCS) or angular stable plating. We performed ten repetitive cycles up to 10°, 20° and 30° rotation, measuring the maximum torque and the average dissipated work at angle level.

RESULTS

Our study showed that rotational stability using a two CCS fixation is significantly (p < 0.05) higher than single CCS fixation. Using the angular stable plate system was also superior to the single CCS (p < 0.05). There was, however, no significant difference between two CCS fixation and angular stable plate fixation.

CONCLUSION

Even though indications of using screws or plate systems might be different and plate osteosynthesis may be preferable in treatment of dislocated or comminuted fractures as well as for nonunions, our study showed a better rotational stability by choosing more than just one screw for osteosynthesis. Angular stable plating of scaphoid fractures also provides more rotational stability than single CCS fixation. The authors therefore hypothesise higher union rates in scaphoid fractures using more stable fixation systems.

A central threadless shaft screw is better than a fully threaded variable pitch screw for unstable scaphoid nonunion: a biomechanical study

INTRODUCTION

An interpositional wedge bone graft is a procedure performed to restore carpal height and scaphoid length for displaced scaphoid nonunions with carpal instability. The purpose of this study was to investigate which headless screw design (threadless central shaft screw or fully threaded variable pitch compression screw) is biomechanically preferred when an interpositional bone graft is needed.

METHODS

A total of 24 cadaveric scaphoid interpositional bone grafts were divided into three groups and fixed with HCS 3.0, Herbert-Whipple or Acutrak mini-screws, and the relative biochemical stability of each was measured. The specimens were tested using an Instron tensile testing machine to calculate stiffness and load to failure. To measure compression forces at different interfragmentary gaps, 30 interpositional polyurethane bone graft models were generated with three pieces of cancellous sawbone block, and two custom-made load-cells were inserted in each gap. The models were then divided into three groups and fixed with the above screw types. The compression forces at different interfragmentary gaps were measured immediately and 30 min after screw fixation.

RESULTS

The average stiffness and load to failure were similar among the three groups (p>0.05). The average compression force measured at each interfragmentary gap was highest in the HCS 3.0 fixation group, followed by the Herbert-Whipple and Acutrak mini-screw fixation groups both immediately after screw fixation and after 30 min (at which time there were significant decreases in force). The compression forces measured at different interfragmentary gaps were almost identical in the HCS 3.0 and Herbert-Whipple screw fixation groups; however, the force measured at the leading side was significantly lower than that measured at the trailing side in the Acutrak mini-screw fixation group.

CONCLUSION

The threadless central shaft screw design is biomechanically preferred over the fully threaded variable pitch screw design because it achieves higher and identical compression forces at different interfragmentary gaps with similar stiffness and load to failure.

Dimensional analysis of the distal phalanx with consideration of distal interphalangeal joint arthrodesis using a headless compression screw

BACKGROUND

Headless compression screws have been used for arthrodesis of the distal interphalangeal joint with good clinical results. However, some distal phalanges are too small, thus precluding their use, or increasing complication rates.

METHODS

In order to validate our digital measurements, radiographs of five cadaveric hands were obtained. The distal phalanges of these fingers were measured using our institution's digital radiograph software. The cadavers were then dissected, and the actual phalanges were measured to confirm the accuracy of the digital measurements; 200 consecutive hand radiographs were then measured to obtain average width and heights of the narrowest measurements of the distal phalanx of each finger. Subgroup analysis of each finger for age and gender was completed.

RESULTS AND CONCLUSIONS

Females were routinely smaller than their male counterparts. No age-related differences were seen. A substantial number of fingers were found to be too small to allow for use of headless compression screws; 42 % of small finger distal phalanges are too small to accommodate 2.8-mm threads, and that number increases to 81 % with 3.2-mm threads and 97 % with 3.5-mm threads. Few distal phalanges, regardless of which finger, are large enough to accommodate 3.5-mm-diameter threads; 22% of female ring finger distal phalanges are smaller than 2.8 mm, and 66 % of ring fingers are smaller than 3.2 mm. Based on our measurements, a surprising number of distal phalanges are smaller than the trailing thread diameter of commonly commercially available headless screws. Care must be taken in selecting implants for distal interphalangeal (DIP) fusion.

A clinical evaluation of alternative fixation techniques for medial malleolus fractures

BACKGROUND

Medial malleolus fractures have traditionally been managed using partially threaded screws and/or Kirschner wire fixation. Using these conventional techniques, a non-union rate of as high as 20% has been reported. In addition too many patients complaining of prominent hardware as a source of pain post-fixation. This study was designed to assess the outcomes of medial malleolar fixation using a headless compression screw in terms of union rate, the need for hardware removal, and pain over the hardware site.

SETTING

Saint Louis University and Mercy Medical Center, Level 1 Trauma Centers, St. Louis, MO.

METHODS

After IRB approval, we used billing records to identify all patients with ankle fractures involving the medial malleolus. Medical records and radiographs were reviewed to identify patients with medial malleolar fractures treated with headless compression screw fixation. Our inclusion criteria included follow-up until full weight bearing and a healed fracture. Follow-up clinical records and radiographs were reviewed to determine union, complication rate and perception of pain over the site of medial malleolus fixation. Sixty-four ankles were fixed via headless compression screws and 44 had adequate follow-up for additional evaluation.

RESULTS

Seven patients had isolated medial malleolar fractures, 23 patients had bimalleolar fractures, and 14 patients had trimalleolar fractures. One patient (2%) required hardware removal due to cellulitis. One patient (2%) had a delayed union, which healed without additional intervention. Ten patients (23%) reported mild discomfort to palpation over the medial malleolus. The median follow-up was 35 weeks (range: 12-208 weeks). There were no screw removals for painful hardware and no cases of non-union.

CONCLUSIONS

Headless compression screws provide effective compression of medial malleolus fractures and result in good clinical outcomes. The headless compression screw is a beneficial alternative to the conventional methods of medial malleolus fixation.

Insertion profiles of 4 headless compression screws

PURPOSE

In practice, the surgeon must rely on screw position (insertion depth) and tactile feedback from the screwdriver (insertion torque) to gauge compression. In this study, we identified the relationship between interfragmentary compression and these 2 factors.

METHODS

The Acutrak Standard, Acutrak Mini, Synthes 3.0, and Herbert-Whipple implants were tested using a polyurethane foam scaphoid model. A specialized testing jig simultaneously measured compression force, insertion torque, and insertion depth at half-screw-turn intervals until failure occurred.

RESULTS

The peak compression occurs at an insertion depth of -3.1 mm, -2.8 mm, 0.9 mm, and 1.5 mm for the Acutrak Mini, Acutrak Standard, Herbert-Whipple, and Synthes screws respectively (insertion depth is positive when the screw is proud above the bone and negative when buried). The compression and insertion torque at a depth of -2 mm were found to be 113 ± 18 N and 0.348 ± 0.052 Nm for the Acutrak Standard, 104 ± 15 N and 0.175 ± 0.008 Nm for the Acutrak Mini, 78 ± 9 N and 0.245 ± 0.006 Nm for the Herbert-Whipple, and 67 ± 2N, 0.233 ± 0.010 Nm for the Synthes headless compression screws.

CONCLUSIONS

All 4 screws generated a sizable amount of compression (> 60 N) over a wide range of insertion depths. The compression at the commonly recommended insertion depth of -2 mm was not significantly different between screws; thus, implant selection should not be based on compression profile alone. Conically shaped screws (Acutrak) generated their peak compression when they were fully buried in the foam whereas the shanked screws (Synthes and Herbert-Whipple) reached peak compression before they were fully inserted. Because insertion torque correlated poorly with compression, surgeons should avoid using tactile judgment of torque as a proxy for compression.

CLINICAL RELEVANCE

Knowledge of the insertion profile may improve our understanding of the implants, provide a better basis for comparing screws, and enable the surgeon to optimize compression.