Are Quadrilateral Surface Buttress Plates Comparable to Traditional Forms of Transverse Acetabular Fracture Fixation?

Background

Several construct options exist for transverse acetabular fracture fixation. Accepted techniques use a combination of column plates and lag screws. Quadrilateral surface buttress plates have been introduced as potential fixation options, but as a result of their novelty, biomechanical data regarding their stabilizing effects are nonexistent. Therefore, we aimed to determine if this fixation method confers similar stability to traditional forms of fixation.

Questions/purposes

We biomechanically compared two acetabular fixation plates with quadrilateral surface buttressing with traditional forms of fixation using lag screws and column plates.

Methods

Thirty-five synthetic hemipelves with a transverse transtectal acetabular fracture were allocated to one of five groups: anterior column plate + posterior column lag screw, posterior column plate + anterior column lag screw, anterior and posterior column lag screws only, infrapectineal plate + anterior column plate, and suprapectineal plate alone. Specimens were loaded for 1500 cycles up to 2.5x body weight and stiffness was calculated. Thereafter, constructs were destructively loaded and failure loads were recorded.

Results

After 1500 cycles, final stiffness was not different with the numbers available between the infrapectineal (568 ± 43 N/mm) and suprapectineal groups (602 ± 87 N/mm, p = 0.988). Both quadrilateral plates were significantly stiffer than the posterior column buttress plate with supplemental lag screw fixation group (311 ± 99 N/mm, p < 0.006). No difference in stiffness was identified with the numbers available between the quadrilateral surface plating groups and the lag screw group (423 ± 219 N/mm, p > 0.223). The infrapectineal group failed at the highest loads (5.4 ± 0.6 kN) and this was significant relative to the suprapectineal (4.4 ± 0.3 kN; p = 0.023), lag screw (2.9 ± 0.8 kN; p < 0.001), and anterior buttress plate with posterior column lag screw (4.0 ± 0.6 kN; p = 0.001) groups.

Conclusions

Quadrilateral surface buttress plates spanning the posterior and anterior columns are biomechanically comparable and, in some cases, superior to traditional forms of fixation in this synthetic hemipelvis model.

Clinical Relevance

Quadrilateral surface buttress plates may present a viable alternative for the treatment of transtectal transverse acetabular fractures. Clinical studies are required to fully define the use of this new form of fixation for such fractures when accessed through the anterior intrapelvic approach.     

Effect of screw fixation on acetabular component alignment change in total hip arthroplasty

Purpose

The use of screws can enhance immediate cup fixation, but the influence of screw insertion on cup position has not previously been measured. The purpose of this study was to quantitatively evaluate the effect of intra-operative screw fixation on acetabular component alignment that has been inserted with the use of a navigation system.

Methods

We used a navigation system to measure cup alignment at the time of press-fit and after screw fixation in 144 hips undergoing total hip arthroplasty. We also compared those findings with factors measured from postoperative radiographs.

Results

The mean intra-operative change of cup position was 1.78° for inclination and 1.81° for anteversion. The intra-operative change of anteversion correlated with the number of screws. The intra-operative change of inclination also correlated with medial hip centre.

Conclusion

The insertion of screws can induce changes in cup alignment, especially when multiple screws are used or if a more medial hip centre is required for rigid acetabular fixation.     

Locking versus standard screw fixation for acetabular cups: is there a difference?

Introduction

Total hip replacement has been established as a valid treatment option for displaced subcapital fractures. However, insufficient primary fixation may be the reason for early loosening in these osteoporotic patients. Primary fixation of the cup is usually achieved by press-fit fixation that can be enhanced using screws. Locking the screws into their respective cups may seem to improve the primary fixation of the construct, as locked plates proved superior fixation for osteoporotic fractures.

Methods

The study consisted of three groups: in each group, three cups were fixed into blocks of foam bone using press-fit technique. In the first group, no additional screws were used, in the second group two standard screws were inserted, while in the third group two acetabular screws were cemented into the cup to simulate locked screw fixation. Load was applied onto the rim of the acetabular component to cause shearing between the cup and the block. Cup fixation was examined by a loading machine that acquired load versus displacement. The stiffness (load vs. displacement) was calculated.

Results

Screws, either locked or non-locked, enhanced cup fixation by 26 % (p value <0.01). No significant changes were found between the locking and non-locking screws groups.

Discussion

These experimental results indicate that acetabular screws enhance primary cup fixation. This may become significant in conditions where the acetabular bone stock is suboptimal, such as when performing total hip arthroplasty after displaced subcapital fractures. However, there is no superiority for locked screws over standard screw fixation.     

The treatment of femoral neck fractures: results using cephalocervical screws with sliding mechanism

Background

A new device for the treatment of femoral neck fractures that uses 2 cephalocervical screws in a sliding mechanism allowing linear intraoperative and postoperative compression has been developed. The purpose of this retrospective study was to determine the results using this device for the treatment of stable and unstable femoral neck fractures.

Methods

Between November 2007 and November 2011, 61 consecutive skeletally mature patients with femoral neck fractures were treated with a new cephalocervical screw (Dual SC screw; KISCO DIR Co., Ltd., Kobe). All contactable patients were followed up for a minimum of 16 weeks postoperatively (range 16–123 weeks). Clinical and radiographic examinations were performed at the final evaluation. Healing and return to activities of daily living were used to evaluate outcomes.

Results

There were 51 women and 10 men with a mean age of 80.8 years (range, 41–99). The average of surgical time was 33.1 min (21–66 min). One patient died, one was too infirm for follow-up, and eleven could not be located, leaving 48 patients available for final evaluation (78.7 %). The overall incidence of nonunion was 10.4 %. Fracture nonunion was less common for undisplaced fractures than for displaced fractures (1 of 21 [4.8 %] vs. 4 of 27 [14.8 %]). The mean amount of collapse of the neck was 5.45 mm (3.92 mm in undisplaced and 6.64 mm in displaced). Radiographic analysis at final evaluation revealed no implant failures. 62.5 % of the patients recovered their prefracture status.

Conclusion

The Dual SC screw device appears to be a reliable implant for the treatment of femoral neck fractures. Its design contributes to overcome the implant failures such as a medial migration, cut-out, or back-out; besides, the union rate of this implant was considered superior to that of existing systems. If the early shortening of the neck occurs after this surgery, the surgeons should be considered to keep them partially weight bearing or choose a replacement procedure for such patients.     

Screw perforation features in 129 consecutive patients performed computer-guided cervical pedicle screw insertion

Study design

A cross-sectional study of the data retrospectively collected by chart review.

Objectives

This study aimed to clarify screw perforation features in 129 consecutive patients treated with computer-assisted cervical pedicle screw (CPS) insertion and to determine important considerations for computer-assisted CPS insertion.

Summary of background data

CPS fixation has been criticized for the potential risk of serious injury to neurovascular structures. To avoid such serious risks, computed tomography (CT)-based navigation has been used during CPS insertion, but screw perforation can occur even with the use of a navigation system.

Methods

The records of 129 consecutive patients who underwent cervical (C2–C7) pedicle screw insertion using a CT-based navigation system from September 1997 to August 2013 were reviewed. Postoperative CT images were used to evaluate the accuracy of screw placement. The screw insertion status was classified as grade 1 (no perforation), indicating that the screw was accurately inserted in pedicle; grade 2 (minor perforation), indicating perforation of less than 50 % of the screw diameter; and grade 3 (major perforation), indicating perforation of 50 % or more of the screw diameter. We analyzed the direction and rate of screw perforation according to the vertebral level.

Results

The rate of grade 3 pedicle screw perforations was 6.7 % (39/579), whereas the combined rate of grades 2 and 3 perforations was 20.0 % (116/579). No clinically significant complications, such as vertebral artery injury, spinal cord injury, or nerve root injury, were caused by the screw perforations. Of the screws showing grade 3 perforation, 30.8 % screws were medially perforated and 69.2 % screws were laterally perforated. Of the screws showing grades 2 and 3 perforation, 21.6 % screws were medially perforated and 78.4 % screws were laterally perforated. Furthermore, we evaluated screw perforation rates according to the vertebral level. Grade 3 pedicle screw perforation occurred in 6.1 % of C2 screws; 7.5 % of C3 screws; 13.0 % of C4 screws; 6.5 % of C5 screws; 3.2 % of C6 screws; and 4.0 % of C7 screws. Grades 2 and 3 pedicle screw perforations occurred in 12.1 % of C2 screws, 22.6 % of C3 screws, 31.5 % of C4 screws, 22.2 % of C5 screws, 14.4 % of C6 screws, and 12.1 % of C7 screws. C3–5 screw perforation rate was significantly higher than C6–7 (p = 0.0024).

Conclusions

Careful insertion of pedicle screws is necessary, especially at C3 to C5, even when using a CT-based navigation system. Pedicle screws tend to be laterally perforated.     

Intraoperative evaluation of dorsal screw prominence after polyaxial volar plate fixation of distal radius fractures utilizing the Hoya view: a cadaveric study

Background

The irregular nature of the dorsal surface of the distal radius makes it difficult to detect prominent screws with volar plate fixation for distal radius fractures using standard fluoroscopic images. This study evaluates the accuracy of a new radiographic method, the Hoya view, for the assessment of dorsal cortical screw penetration with volar plate fixation.

Methods

Eight cadaveric upper extremities underwent application of a volar distal radius plate with polyaxial locking screws placed distally. Utilizing a mini C-arm, lateral and Hoya views were obtained with notation of any dorsal cortical screw prominence. Dissection of the cadavers was then performed for direct visualization of screw prominence. The screws were then exchanged sequentially for screws 2-mm longer than their initial measurements with repeated imaging and direct visualization.

Results

The Hoya view revealed that 9.4 % of the screws penetrated the dorsal cortex with an average screw prominence of 1.08 mm (range 0.5–2 mm). None of the six prominent screws were detected with lateral views. With the Hoya view, six of six prominent screws were identified. With locking screws exchanged for screws 2-mm longer, 76.6 % of the screws had violated the dorsal cortex; of these, 24.5 % were detected with lateral imaging versus 100 % with the Hoya view.

Conclusions

This study supports the intraoperative use of the Hoya view to evaluate screw length and dorsal cortical screw penetration in volar plate fixation of distal radius fractures. However, this view may be difficult to obtain in patients with limitations in elbow or shoulder range of motion.     

Paediatric lateral humeral condyle fractures: internal oblique radiographs alter the course of conservative treatment

Introduction

At first presentation of paediatric humeral lateral condyle fractures, radiological methods such as computerised tomography, ultrasonography, magnetic resonance imaging, arthrography, and internal oblique radiography are used to determine stability. Very few studies show which radiological method should be used to evaluate displacement at follow-up for conservatively treated patients. This study aimed to show that internal oblique radiography is a simple, effective method to determine the subsequent development of fracture displacement in patients with an initially non-displaced or minimally displaced fracture.

Materials and methods

In this retrospective study, 27 paediatric patients with non-displaced or minimally displaced (<2 mm) humerus lateral condyle fracture were evaluated by elbow anteroposterior radiograph. The degree of fracture displacement was evaluated by anteroposterior then by internal oblique radiographs. The first follow-up was made between the 5th and 8th day and thereafter at intervals of 7–10 days.

Results

Of the 27 patients identified with non-displaced or minimally displaced (<2 mm) fracture from the initial anteroposterior radiograph, 16 were accepted as displacement >2 mm as a result of the evaluation of the internal oblique radiography and underwent surgery. At follow-up, 2 of 11 patients were defined with displacement from anteroposterior and internal oblique radiographs and 4 from the internal oblique radiographs and underwent surgery. Conservative treatment was applied to 5 patients.

Conclusions

Internal oblique radiography is the best imaging showing subsequent fracture displacement in initially non-displaced or minimally displaced humerus lateral condyle fractures. At the first week follow-up, anteroposterior and particularly internal oblique radiographs should be taken of conservatively treated patients.     

Revision rates and cumulative financial burden in patients treated with hemiarthroplasty compared to cannulated screws after femoral neck fractures

Introduction

This study compares re-operation rates and financial burden following the treatment of femoral neck fractures treated with hemiarthroplasty compared to non-displaced femoral neck fractures treated with cannulated screws.

Methods

Data was retrospectively analyzed from a prospective database at a university hospital setting on patients undergoing hemiarthroplasty after femoral neck fractures and those with non-displaced femoral neck fractures treated with cannulated screws over a 7-year period. Re-operation rates were determined and financial data was analyzed. Charges refer to amounts billed by the hospital to insurance carriers, while costs refer to financial burden carried by the hospital during treatment.

Results

There were 491 femoral neck fractures (475 patients) that underwent hemiarthroplasty (HA) and 120 non-displaced fractures (119 patients) treated with cannulated screw (CannS) fixation. Both groups had similar age, sex, Charlson co-morbidity scores, pre-operative Parker mobility scores, and 12-month mortality. There were 29 (5.9 %) reoperations in the HA group and 16 (13.3 %) in the CannS group (P = 0.007). The majority of re-operations occurred within 12 months for both groups [21/29 (72 %) HA group; 15/16 (94 %) CannS group; P = 0.13]. Average hospital charges per patient for the index procedure were higher in the HA group ($17,880 ± 745) compared to the CannS group ($14,104 ± 5,047; P < 0.001). After accounting for additional procedures related to their initial surgical fixation, average hospital charges and costs remained higher in the HA group.

Conclusion

Patients treated with hemiarthroplasty for femoral neck fractures have lower re-operation rates than patients treated with cannulated screws for non-displaced femoral neck fractures, with 80 % of re-operations occurring in the first 12 months. Hospital charges and costs to the hospital for treating patients undergoing hemiarthroplasty were higher than patients treated with cannulated screws for the index procedure alone, and after accounting for re-operations.     

Management of severe periacetabular bone loss combined with pelvic discontinuity in revision hip arthroplasty

Purpose

Revision of failed total hip arthroplasty with massive acetabular bone loss resulting in pelvic discontinuity represents a rare but challenging problem. The objective of this study was to present short to mid-term results of revision total hip arthroplasty with a custom-made acetabular implant in a consecutive series of patients with pelvic discontinuity.

Methods

We retrospectively reviewed 18 consecutive patients with massive acetabular bone loss (Paprosky Type 3B) resulting in pelvic discontinuity reconstructed with revision total hip arthroplasty using a custom-made acetabular component. The prosthesis was created on the basis of a thin-cut 1-mm computed tomography (CT) scan of the pelvis. Initial stability of the implant was obtained by screw fixation. Harris hip score and sequential radiographs were used to evaluate the clinical and radiographic results.

Results

At an average follow up of 30 months (range 17–62 months) 16 of 18 (88.9 %) custom-made implants were considered radiographically stable without signs of acetabular migration of more than 2 mm in the horizontal or vertical direction, implant rotation or screw breakage. Complications included two periprosthetic joint infections treated with explantation of the implant. Three patients had recurrent dislocations postoperatively. The mean Harris hip score improved from 28?±?12 points preoperatively to 69?±?13 points at the time of last follow up.

Conclusion

Treatment of acetabular bone loss and pelvic discontinuity with a custom-made acetabular component can provide a durable solution with good clinical and radiographic results.     

Percutaneous fixation of acetabular fractures: computer-assisted determination of safe zones, angles and lengths for screw insertion

Introduction

Percutaneous retrograde screw fixation for acetabular fractures is a demanding procedure due to the complex anatomy of the pelvis and the varying narrow safe bony corridors. Limited information is available on optimal screw placement and the geometry of safe zones for screw insertion in the pelvis.

Methods

Three-dimensional reconstructions of 50 consecutive CT scans of polytrauma patients (35 males, 15 females) were used to introduce three virtual CAD bolts (representing screws) into the anterior column (superior ramus of the pubic bone), posterior column (the ischial bone) and the supraacetabular region, as performed during percutaneous screw fixation. The three-dimensional (3D) position of these screws was evaluated with a computer software (MIMICS) after virtual optimal insertion. The 3D position, the narrowest zone and the distance to the hip joint of the two columns and the supraacetabular region were defined.

Results

The mean maximal screw length for the three virtual screws measured between 107.4 and 148?±?18.7?mm. The narrowest zone of the pelvic bone (superior pubic ramus) had a width of 9.2?±?2.4?mm. The average distances between the bolts and the hip joint were 3.9 and 19.4?±?7.4?mm. For the anterior column (superior pubic ramus) screw, the mean lateral angle to the sagittal midline plane was 39.0?±?3.2° and the mean posterior angle to the transversal midline plane was 15.1?±?4.0°. The mean supraacetabular screw angles measured 22.4?±?3.4° (medial), 35.3?±?4.6° (cranial) and the mean angles for the ischial screw were 12.0?±?5.4° (posterior) and 18.4?±?4.0° (lateral).

Conclusions

The zones for safe screw positioning are very narrow, making percutaneous screw fixation of the acetabulum a challenging procedure. The predefined angles for the most frequently positioned percutaneous screws may aid in preoperative planning, decrease operative and radiation times and help to increase safe insertion of screws.     

A new fixation method for Hoffa fracture

Purpose

To investigate the clinical effect of a new fixation method for Hoffa fractures.

Methods

We treated eleven patients with Hoffa fracture using the new fixation method (fixation with one screw inserted from the femoral intercondylar notch and two screws inserted from the nonarticular lateral (or medial) surface of the fractured condylar fragment; the two sets of screws were crossed).

Results

After an average follow-up period of 24 months (range 5–28 months), all fractures had healed. The average healing time was 11.6 weeks (range 9–14 weeks). On the version of the Knee Society Score modified by Dr. John Insall in 1993, the average score was 174.6 points (range 125–199 points).

Conclusions

The new fixation method for Hoffa fracture is effective, and may provide a new way to treat Hoffa fractures.     

Position of polyaxial versus monoaxial screws in locked plating for proximal humeral fractures: analysis of a prospective randomized study

Background

Aim of the study was to compare the chosen position of polyaxial locking screws with the position of monoaxial screws in the humeral head of proximal humeral fractures treated by locked plating.

Methods

In a prospective randomized observational study, 124 consecutive patients (mean age 70.9 ± 14.8 years) sustaining a displaced proximal humeral fracture were treated with either monoaxial or polyaxial screw-inserted locking plate fixation. The chosen positions of locking screws were identified from standardized postoperative radiographs in anteroposterior and outlet-view, with regard to a regional mapping of the humeral head.

Results

In monoaxial locking technique, a mean of 6 screws purchased the humeral head (95 % CI 5.1–6.2), and in polyaxial locking technique, a mean of 4 screws (95 % CI 3.3–4.5), respectively. Screws were placed in the regions superolateral: monoaxial 24.8 %, polyaxial 20.7 % (p = 0.49); superomedial: monoaxial 21.9 %, polyaxial 20.0 % (p = 0.433); inferolateral: monoaxial 32.5 %, polyaxial 35.0 % (p = 0.354); inferomedial: monoaxial 20.8 %, polyaxial 24.2 % (p = 0.07), superoposterior: monoaxial 45.5 %, polyaxial 30.8 % (p = 0.57); superoanterior: monoaxial 4.4 %, polyaxial 8.3 % (p = 0.33); inferoposterior: monoaxial 22.5 %, polyaxial 29.8 % (p = 0.49) and inferoanterior: monoaxial 27.5 %, polyaxial: 31.2 % (p = 0.09).

Conclusion

The chosen screws’ position in monoaxial and polyaxial locking plate fixation of displaced proximal humeral fractures do not differ significantly. However, loss of fixation is observed more frequently if the fixation did not include at least one screw within the superoposterior region of the humeral head, suggesting that a screw purchasing the superoposterior region is beneficial in locked plating of proximal humeral fractures.

Level of evidence

Treatment Study, Level II.     

Free-hand placement of occipital condyle screws: a cadaveric study

Purpose

Cranio-vertebral junction fixation is challenging due to the complex topographical anatomy and the presence of important anatomical structures. There are several limitations to the traditional occipital squama fixation methods. The purpose of this work is to assess the safety and feasibility of a new optimum trajectory of occipital condyle (OC) screws for occipitocervical fixation via a free-hand technique.

Methods

Eight different parameters of OC morphology were studied in fifty adult skulls. Free-hand placement of OC screws was performed in five cadavers using 3.5-mm titanium polyaxial screws and a 3-mm rod construct (C0–C1–C2). Postoperative computed tomography was performed to determine the success of the screw placement and their angulation, length and effect on hypoglossal canal volume.

Results

The average length, width and height of the OC were 24.2 ± 3.6, 14.2 ± 1.9, and 10.7 ± 2 mm, respectively. The average medio-lateral, hypoglossal canal and atlanto-occipital joint angles were 38.8° medially ±5°, 7.4° rostrally ±1.9° and 23.4° caudally ±3.5°, respectively. The ten screws were successfully inserted using a free-hand technique with bicortical purchase. There was no vertebral artery injury or breach of the hypoglossal canal in any specimen. The average screw length was 22.2 ± 3.9 mm. The average medio-lateral angle was 30° medially ±6.7°. The average cranio-caudal angle was 4° caudally ±6.2°.

Conclusions

The free-hand technique of OC screw placement is a safe and viable option for occipitocervical fixation and may be a preferred alternative in selected cases. However, further studies are needed to compare its safety and reliability to other more established methods.     

The effect of two different trochanteric nail lag-screw designs on fixation stability of four-part intertrochanteric fractures: a clinical and biomechanical study

Objectives

To compare lag-screw sliding characteristics and fixation stability of two cephalomedullary nails (CMN) with different lag-screw designs (solid and telescopic), we conducted a biomechanical study and an analysis of clinical results.

Methods

Six pairs of cadaver femurs with simulated intertrochanteric fractures were randomly assigned to one of two CMN fixations. Femur constructs were statically then cyclically loaded on an MTS machine. Lag-screw sliding and inferior and lateral femoral head displacements were measured, following which failure strength of the construct was determined. Forty-five patients with intertrochanteric fractures treated with these CMN were identified. Medical records and radiographs were reviewed and analyzed using Fisher’s exact test and Student’s t test to determine lag-screw sliding.

Results

No difference was seen with cycling in inferior femoral head displacement between the two screw designs. The solid screw had an average inferior head displacement of 1.75 mm compared with 1.59 mm for the telescoping screw (p = 0.772). The solid lag screws slid an average of 2.79 mm lateral from the nail, whereas the telescoping screws slid an average of 0.27 mm (p = 0.003). In our clinical review, the average lateral sliding of the telescoping screw was 0.5 mm and of the solid screw was 3.7 mm (p < 0.001). Despite differences in lateral sliding, there were no reoperations for prominent or painful hardware in either group.

Conclusions

Both designs are acceptable devices for stabilization of intertrochanteric fractures. Clinical and biomechanical data demonstrate greater lateral sliding in the solid lag-screw group, making for greater potential for lateral-sided hip pain in CMNs with solid lag screws as opposed to telescoping lag screws.     

Percutaneous screw fixation for the acetabular fracture with quadrilateral plate involved by three-dimensional fluoroscopy navigation: surgical technique

BackgroundThe percutaneous three-dimensional (3D)-fluoroscopic-navigated screw directing to the quadrilateral plate was attempted.Materials and methodsFive patients with acetabular fractures were treated by 3D navigated percutaneous screw. The quadrilateral plate was involved in all the patients. The Arcadis 3D (ARCADIS Orbic 3D^®; Siemens AG Healthcare Sector, Erlangen, Germany) and computer navigation system (stryker navigation system) were employed, screwing trajectory was attempted to anchor the quadrilateral plate perpendicularly to the fracture line and close to the joint cartilage as much as possible. Parameters including fracture gap closure (P1), distance to the joint cartilage (P2), angulations between the screw and the fracture line (P3), were measured with the software installed on the machine of Arcadis 3D.ResultSeven screws were inserted with the use of 3D fluoroscopic navigation. The quadrilateral plate was hold by percutaneous screws. The closure of fracture gap was achieved in 3 patients by 2–3 mm. The nearest distance from the screw to the joint cartilage was ranged from <1 mm to 6 mm. The angulations between the screw and the fracture line was 80–90° in three patients, it was 60° and 65° respectively on the rest two patients. All patients felt pain free 1 week after the operation. No complication was noted postoperatively.ConclusionThe surgical technique of percutaneous screwing for the acetabular fracture with three-dimensional fluoroscopy-based navigation was demonstrated.     

Accuracy of lower cervical pedicle screw placement with assistance of distinct navigation systems: a human cadaveric study

Purpose

Evaluate the accuracy of five different techniques for lower cervical pedicle screw placement.

Methods

Forty human cadaveric cervical spines were equally divided into five groups, and each group had eight specimens. Pedicle screws with dia. 3.5 mm were used. Group 1 was blind screw placement without any assistance; Group 2–5 was assisted by the X-ray fluoroscopy, virtual fluoroscopy navigation system, CT-based navigation system, and Iso-C 3D navigation system, respectively. Thereafter, cortical integrity of each pedicle was evaluated by anatomic dissection of the specimens.

Results

A total of 398 pedicle screws were inserted. In the Group 1–5, the average operation time per sample was 27 ± 3.0, 112 ± 10.3, 69 ± 6.4, 98 ± 11.0, and 91 ± 6.0 min, respectively. The outcome for excellent, fair and poor were 29 (36.3 %), 21 (26.2 %) and 30 (37.5 %) in Group 1; 35 (44.9 %), 29 (37.2 %) and 14 (17.9 %) in Group 2; 34 (42.5 %), 36 (45.0 %) and 10 (12.5 %) in Group 3; 70 (87.5 %), 10 (12.5 %) and 0 (0.0 %) in Group 4; 72 (90.0 %), 8 (10.0 %) and 0 (0.0 %) in Group 5.

Conclusions

Blind screw placement was surely unsafe. Lower cervical pedicle screw placement assisted by the CT-based navigation system or the Iso-C 3D navigation system significantly improved the accuracy compared to the fluoroscopy assistance and the virtual fluoroscopy navigation assistance.     

Comparison between bovine bone and titanium interference screws for implant fixation in ACL reconstruction: a biomechanical study

Introduction

The application of interference screws for the fixation of bone-patellar tendon-bone (BPTB) grafts is a well-established technique in anterior-cruciate ligament reconstruction. Interference screws derived from bovine compact bone are a biological alternative to metallic or biodegradable polymer interference screws.

Materials and methods

In 60 porcine specimens, the tibial part of an anterior-cruciate ligament reconstruction was performed using a BPTB graft. To secure the graft, either an 8-mm titanium interference screw or a self-made bovine interference screw (BC), or a commercial bovine compact bone screw (Tutofix^®) was used. The maximum failure load was determined by means of a universal testing machine with computer interface at a testing speed of 50 mm/min. In a second test series, cyclic sub-maximal load was applied to the test specimen from 40 to 400 N with a number of 1,000 load cycles and a frequency of 1 Hz. Subsequently, the maximum failure load was determined. The stiffness of the test specimen was investigated in both test series. Each type of interference screw was tested 10 times.

Results

A secure fixation of the grafts was achieved with all interference screws. In the experiments on the maximum load to failures, the titanium screws showed significantly higher failure loads than the Tutofix^® screws (P = 0.005). The stiffness of the grafts fixed with BC screws was significantly higher as compared to the fixation with Tutofix^® screws (P = 0.005). After cyclic sub-maximal loading, the maximum failure load of the titanium screws was significantly higher than that of the Tutofix^® screws (P = 0.033). The fixation of the BC screws showed a significantly higher failure load (P = 0.021) and stiffness (P = 0.032) than the Tutofix^® screw fixation. Except for two screw head fractures and two intra-tendinous graft ruptures, the failure mode was slippage in the interface between interference screw and bone plug.

Conclusion

Interference screws derived from bovine compact bone show similar good results as the titanium interference screws. Therefore, the safety and in vivo performance of products derived from xenogenic bone should be the focus of further investigations.     

Displaced mid-shaft clavicular fractures: surgical treatment with intramedullary screw fixation

Introduction

Clavicle fractures account for around 4 % of all fractures and up to 44 % of fractures of the shoulder girdle. Fractures of the middle third account for approximately 80 % of all clavicle fractures. Management of mid-shaft clavicular fractures is often challenging and the outcome can be unsatisfactory.

Materials and methods

We prospectively evaluated 20 patients (16 males and 4 females) with an average age of 31 years (range 18–50 years) presented with fresh mid-shaft clavicular fractures who underwent open intramedullary fixation using a 6.5 partially threaded cancellous screw. The screw was inserted from the lateral fragment after retrograde drilling of that fragment. Average follow-up period was 16 months (range 10–24).

Results

All cases united within 7–9 weeks (mean 8.2). Superficial infection was observed in one patient, three experienced decreased sensation over the site of incision, and four had symptoms of frozen shoulder.

Discussion and conclusion

The technique is safe, simple, reliable method for fixation of displaced mid-shaft clavicle fractures with minimal complications and excellent functional outcomes. No complaints or indications for hardware removal after fractures healing.     

Accuracy of screw fixation using the O-arm<Superscript>®</Superscript> and StealthStation<Superscript>®</Superscript> navigation system for unstable pelvic ring fractures

Purpose

Screw fixation for unstable pelvic ring fractures is generally performed using the C-arm. However, some studies reported erroneous piercing with screws, nerve injuries, and vessel injuries. Recent studies have reported the efficacy of screw fixations using navigation systems. The purpose of this retrospective study was to investigate the accuracy of screw fixation using the O-arm^® imaging system and StealthStation^® navigation system for unstable pelvic ring fractures.

Methods

The participants were 10 patients with unstable pelvic ring fractures, who underwent screw fixations using the O-arm StealthStation navigation system (nine cases with iliosacral screw and one case with lateral compression screw). We investigated operation duration, bleeding during operation, the presence of complications during operation, and the presence of cortical bone perforation by the screws based on postoperative CT scan images. We also measured the difference in screw tip positions between intraoperative navigation screen shot images and postoperative CT scan images.

Results

The average operation duration was 71 min, average bleeding was 12 ml, and there were no nerve or vessel injuries during the operation. There was no cortical bone perforation by the screws. The average difference between intraoperative navigation images and postoperative CT images was 2.5 ± 0.9 mm, for all 18 screws used in this study.

Conclusion

Our results suggest that the O-arm StealthStation navigation system provides accurate screw fixation for unstable pelvic ring fractures.

     

Posterior fixation of type IV humeral capitellum fractures with fully threaded screws in adolescents

Purpose

Humeral capitellum fractures comprise approximately 1% of all elbow fractures. In this study, we examined the clinical, radiographic, and functional outcomes following operative stabilization of Bryan and Morrey type IV fractures of the capitellum in adolescents. We applied headless cannulated screws in a posteroanterior direction without damaging the articular cartilage surface of the fractures.

Methods

Eight adolescent patients (six male, two female) with a mean age of 15 ± 2.1 years (range 13–18 years) were treated for type IV (McKee) humerus capitellum fractures. In the preoperative radiological evaluation, anteroposterior and lateral radiographs and computed tomography (CT) images were performed. A lateral surgical approach was used, and cannulated fully threaded headless screws were applied in a posteroanterior direction as fixation materials in the fracture reduction. The Mayo Elbow Performance Score was used in the evaluation of elbow joint functions.

Results

Patients were followed up for a mean of 24.6 months. Fracture union was achieved at a mean of 5 ± 0.92 weeks (range 4–6 weeks). The mean elbow extension flexion arc was 135° ± 13.47° (range 110°–150º) and the mean pronation supination arc was 156° ± 4.43° (150°–160°). In one patient, there was nonconformity in the humerus trochlea and in another patient, there was keloid formation on the surgical scar. All patients attained excellent results according to the Mayo Elbow Performance Score.

Conclusions

In the treatment of type IV capitellum fractures in adolescents, open reduction with a lateral surgical approach and fixation using posteroanterior directed, cannulated, fully threaded, headless screws is a reliable method to achieve a pain-free functional elbow joint.