Chondrocyte death after drilling and articular screw insertion in a bovine model

SummaryObjectiveIntra-articular screws are used for internal fixation of osteochondral fragments after fracture or osteochondritis dissecans. This causes cartilage injury potentially leading to chondrocyte death. We have visualised/quantified the hole and zone of cell death (ZCD) in cartilage after drilling/insertion of various articular screws.MethodUsing an ex vivo bovine model with transmitted light and confocal laser scanning microscopy (CLSM), the holes and ZCD following drilling/insertion of articular screws (cortical screw, headless variable pitch metallic screw, headless variable pitch bioabsorbable screw) were evaluated. In situ chondrocyte death was determined by live/dead cell viability assay. An imaging/quantification protocol was developed to compare hole diameter and ZCD from drilling/insertion of screws into cartilage. The effect of saline irrigation during drilling on the ZCD was also quantified.ResultsScrew insertion created holes in cartilage that were significantly (P ≤ 0.001) less than the diameters of the equipment used. With a 1.5 mm drill, a ZCD of 580.2 ± 124 μm was produced which increased to 637.0 ± 44 μm following insertion of a 2 mm cortical screw although this was not significant (P > 0.05). The ZCD from insertion of the variable pitch headless screws (diam. 3.5 mm) was lower for the metallic compared to the bioabsorbable design (800.9 ± 159 vs 1,236.4 ± 212 μm, respectively; P < 0.01). The ZCD from drilling was reduced ∼50% (P < 0.001) by saline irrigation.ConclusionsCartilage injury during intra-articular screw fixation caused a ZCD around the hole irrespective of screw design. Saline irrigation significantly reduced the ZCD from drilling into cartilage

Biomechanical evaluation of a 6.5-mm headless, tapered variable pitch screw (Acutrak Plus) in equine and synthetic bone

Objectives – To compare compression pressure (CP) of 6.5mm Acutrak Plus (AP) and 4.5mm AO cortical screws (AO) when placed in simulated lateral condylar fractures of variable thickness in cadaveric equine third metacarpal (MC3) bones, and to compare pullout force and strength of AP and AO screws when placed in a synthetic bone substitute. Results – The AO screw configurations generated significantly greater compressive pressure compared to the AP configurations. The ratio of mean CP for AP screws to AO screws at 20, 12, and 8-mm, were 21.6%, 26.2%, and 34.2% respectively. For the pullout study, the AP constructs generated a significantly higher pullout force and strength (60% greater) when compared to the AO constructs. Conclusion – Mean CP for AP screw fixations are weaker than those for AO screw fixations, most notably with the 20 mm fragments. The 12- and 8-mm groups have comparatively better compression characteristics than the 20-mm group, however they are still significantly weaker than the AO fixations. Pullout characteristics for AP screws were expected however don’t correlate with compressions characteristics based mainly on screw thread design. Clinical Relevance – Given that the primary goals of surgical repair are to achieve rigid fixation, primary bone healing, and good articular alignment, based on these results, it is recommended that caution should be used when choosing the AP screw for repair of lateral condylar fractures, especially complete fractures. Since interfragmentary compression plays a factor in the overall stability of a repair, it is recommended for use only in patients with thin lateral condyle fracture fragments, as the compression tends to decrease with an increase in thickness. Typically, pullout and compression characteristics are directly proportional for many compression screws, but based on screw thread design, most notably the thread pitch and angulation, greater pullout characteristics are expected with the AP screw without the concurrent increased compressive force and strength. Further works needs to be performed including single cycle to failure and cyclic fatigue testing prior to use in clinical cases

A comparison of two headless compression screws for operative treatment of scaphoid fractures

<p>Abstract</p> <p>Purpose</p> <p>The purpose of this study was to compare the interfragmentary compression force across a simulated scaphoid fracture by two commonly used compression screw systems; the Acutrak 2 Standard and the 3.0 mm Synthes headless compression screw.</p> <p>Methods</p> <p>Sixteen (8 pairs; 6 female, 2 male) cadaver scaphoids were randomly assigned to receive either the Acutrak 2 or Synthes screw with the contralateral scaphoid designated to receive the opposite. Guide wires were inserted under fluoroscopic control. Following transverse osteotomy, the distal and proximal fragments were placed on either side of a custom load cell, to measure interfragmentary compression. Screws were placed under fluoroscopic control using the manufacturer's recommended surgical technique. Compressive forces were measured during screw insertion. Recording continued for an additional 60s in order to measure any loss of compression after installation was complete. The peak and final interfragmentary compression were recorded and paired t-tests performed.</p> <p>Results</p> <p>The mean peak compression generated by the Acutrak 2 Standard was greater than that produced by the Synthes compression screw (103.9 ± 33.2 N vs. 88.7 ± 38.6 N respectively, p = 0.13). The mean final interfragmentary compression generated by the Acutrak 2 screw (68.6 ± 36.4 N) was significantly greater (p = 0.04) than the Synthes screw (37.2 ± 26.8 N). Specimens typically reached a steady state of compression by 120-150s after final tightening.</p> <p>Conclusion</p> <p>Peak interfragmentary compression observed during screw installation was similar for both screw systems. However, the mean interfragmentary compression generated by the Acutrak 2 Standard was significantly greater. Our study demonstrates that the Synthes headless compression screw experienced a greater loss of interfragmentary compressive force from the time of installation to the final steady state compression level. The higher post-installation compression of the Acutrak 2 Standard may be attributable to the greater number of threads throughout the entire length of the screw. The clinical significance of these results, are, at this point uncertain. We do demonstrate that a fully threaded design offers a more reliable compression that may translate to more predictable bony union.</p

Four Cases with Rare Complications of Intramedullary Screw Fixation for Jones Fracture

Active treatment with intramedullary screw fixation is now common for athletes with Jones fracture. Outcomes are generally good, but complications can occur. We report 4 rare complications of intramedullary screw fixa-tion. Two cases developed osteomyelitis and pseudarthrosis caused by thermal necrosis. In the other two cases, screw-related complications occurred during the insertion of the tapered headless screw. Although thermal necrosis and screw insertion failures are considered rare complications and not widely reported in the litera-ture, they do occur occasionally. Knowing the mechanisms underlying these complications could help prevent them, and knowing their course could lead caregivers to appropriate interventions when they do occur

The treatment of talar body fractures with compression screws: a case series

Fractures of talar body are rare and serious injuries and frequently seen in multiply injured and polytraumatised patients. The high variability of talar fractures, their relatively low incidence together with the high percentage of concomitant injuries makes treatment of these injuries a challenge to the surgeon

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.ope

Experimental trial on surgical treatment for transverse fractures of the proximal phalanx: technique using intramedullary conical compression screw versus lateral compression plate

AbstractObjectiveTo compare the mechanical parameters between two methods for stabilization through compression: 1.5mm axial compression plate versus conical compression screw used as an intramedullary tutor.MethodsPolyurethane models (Sawbone®) that simulated transverse fractures of the proximal phalanx were used. The models were divided into three groups: lateral plate, conical screw and no implant.ResultsGreater force was needed to result in fatigue in the synthesis using an intramedullary plate. Thus, this model was proven to be mechanically superior to the model with the lateral plate.ConclusionStabilization using the Acutrak® screw for treating fractures in the model used in this trial presents mechanical results that are statistically significantly superior to those from the axial compression technique using the lateral plate (Aptus Hand®)

Avulsion Fractures at the Base of the 2^nd Metacarpal Due to the Extensor Carpi Radialis Longus Tendon: A Case Report and Review of the Literature

Introduction: Simultaneous contraction of the extensor carpi radialis longus (ECRL) with forced hyperflexion of the wrist can result in avulsion of the tendon and its bony attachment at its insertion at the dorsum of the base of the second metacarpal. This is a rare and often unreported fracture pattern. Case Presentation: We present a 31- year- old male who sustained a hyperflexion injury. He was managed surgically and had good post-operative outcomes. A literature search revealed 16 papers covering 18 cases of similar injuries. 12 were initially managed surgically and 6 were managed conservatively. Conclusions: Of the open reductions and internal fixations, 11 (92%) were successful and patients made a full recovery. Conservative management was unsuccessful in 4 cases; one patient required surgery for metacarpal boss, one patient had retraction of the tendon at one week follow up and another had weak flexion of the wrist. We recommend open reduction and internal fixation for these injuries. It may allow a faster recovery and therefore allow an earlier return to work and activit

The Implants used for Intramedullary Fixation of Distal Fibula Fractures : A Review of Literature

Peer reviewedPostprin