Distal Femoral Locking Compression Plate Fixation in Distal Femoral Fractures: Early Results. Malaysian Orthopaedic Journal, 1 (1). pp. 12-17. ISSN 1985 2533 Abstract : We conducted a retrospective review on eleven patients who were treated for Type A and C distal femoral fractures (based on AO classification) between January 2004 and December 2004. All fractures were fixed with titanium distal femoral locking compression plate. The patient’s ages ranged from 15 to 85 with a mean of 44. Clinical assessment was conducted at least 6 months post-operatively using the Schatzker scoring system. Results showed that four patients had excellent results, four good, two fair and one failure.
Biomechanical analysis of distal femur fracture fixation: fixed- angle screw-plate construct versus condylar blade plate J Orthop Trauma. 2007 Jan;21(1):43-6.. The objective of this study is to establish the relative strength of fixation of a locking distal femoral plate compared with the condylar blade plate. Eight matched pairs of fresh-frozen cadaveric femurs were selected and evaluated for bone density. RESULTS: Significantly greater subsidence (total axial displacement) occurred with the blade plate (1.70 +/- 0.45 mm; range, 1.21-2.48 mm) than with the locking plate fixation (1.04 +/- 0.33 mm; range, 0.67-1.60 mm) after cyclic loading (P = 0.03). In load-to-failure testing, force absorbed by the locking plate before failure (9085 +/- 1585 N; range, 7269-11,850 N) was significantly greater than the load tolerated by the blade plate construct (5591 +/ - 945 N; range, 3546-6684 N; P = 0.001). CONCLUSIONS: The locking screw-plate construct proved stronger than the blade plate in both cyclic loading and ultimate strength in biomechanical testing of a simulated A3 distal femur fracture.
Distal femoral fixation: a biomechanical comparison of trigen retrograde intramedullary (i.m.) nail, dynamic condylar screw (DCS), and locking compression plate (LCP) condylar plate. J Trauma. 2009 Feb;66(2):443-9 BACKGROUND: The purpose of this study was to establish if there are biomechanical differences between implants in stiffness of construct, microdisplacement, and fatigue failure in a supracondylar femoral fracture model. METHODS: A retrograde intramedullary (i.m.) nail, dynamic condylar screw (DCS), and locked condylar plate (LCP) were tested using 33-cm long synthetic femurs. A standardized supracondylar medial segmental defect was created in the distal femur bone models. RESULTS: It was observed that there were statistically significant differences in micromotion across the fracture gap and overall stiffness of various implant constructs. The stiffness of the i.m. nail, DCS, and LCP were 1,106, 750, and 625 N/mm, respectively. The average total micromotion across the fracture gap for the i.m. nail, DCS, and LCP were 1.96, 10.55, and 17.74 mm, respectively. In fatigue testing, the i.m. nail distal screws failed at 9,000 cycles, the DCS did not fail (80,000 cycles completed), and the LCP failed at 19,000 and 23,500 cycles. CONCLUSIONS: When considering micromotion and construct stiffness, the i.m. nail had statistically significant higher stiffness and significantly lower micromotion across the fracture gap with axial compression. Hence, the i.m. nail tested had the greatest stability for type 33-A fractures. However, the nail demonstrated the least amount of resistance to fatigue failure with type 33-C fractures, whereas the DCS did not fail with testing in any pattern.
Polyaxial locking plate fixation in distal femur fractures: a biomechanical comparison. J Orthop Trauma. 2008 Oct;22(9):624-8. Bachground: This study compares the mechanical stability of a conventional locking plate with that of a new polyaxial design. METHODS: A comminuted supracondylar femur fracture (AO/OTA33-A3) gap model was created in fourth-generation synthetic composite bones. Fixation was obtained with 2 different plate constructs: (1) a conventional locking plate (uniaxial screw heads threading directly into plate) and (2) a polyaxial locking plate (screw heads are captured and "locked" into a fixed angle using locking caps). Eight specimens of each type were then tested in axial, torsional, and cyclic axial modes on a material testing machine. RESULTS: The mean axial stiffness for the polyaxial locking plate was 24.4% greater than the conventional locking plate (168.2 vs 127.1 N/mm; P < 0.0001). The mean torsional stiffness was also greater for the polyaxial plate (2.78 vs 2.57 Nm/degree; P = 0.0226). Cyclic axial loading caused significantly less (P = 0.0034) mean irreversible deformation in the polyaxial plate (5.6 mm) than in the conventional plate (8.8 mm). The mean ultimate load to failure was significantly higher (P = 0.0005) for the polyaxial plate (1560 N) than for the conventional plate (1337 N). CONCLUSIONS: The tested plate construct with its polyaxial locking screw mechanism provides a biomechanically sound fixation option for supracondylar femur fractures. The frictional locking mechanism allows maintenance of angular stability while affording the option of variable screw placement.
LISS stands for Less Invasive Stabilization System. A LISS plate is similar to a buttress plate with several modifications. The screw holes in a LISS plate are round and threaded so that the screws are locked onto the plate. This allows adequate stabilization with only unicortical screws rather than the bicortical fixation required with standard compression or buttress plates. The plate does not have to be close to bone and therefore it does not need to be closely contoured to the periarticular surface as with a standard buttress plate (note the simple shape of the distal end of the plate). These modification allow easier insertion and less damage to the bone and its blood supply. Note the specially shaped unicortical screws used with the LISS plate
LISS plate fixation Treatment Of Distal Femoral Fractures Using The Less Invasive Stabilization System (LISS) Plates J.Orthopaedics 2008;5(4)e10 J.Orthopaedics 2008;5(4)e10 Purpose: To review clinical and radiological outcome of distal femoral fractures treated with the Less Invasive Stabilisation System (LISS). Results: A total of 40 patients were identified. Amongst these, 3 patients were lost to follow up or died and 37 patients (24 females and 13 males) were included in final analysis. There were 23 acute femoral fractures and 14 periprosthetic fractures. The commonest cause of injury was simple mechanical fall. According to the AO classification, 15 patients with type 33A, 4 patients with type 33C, 13 patients with type 32A and 2 patients with type 32B and 3 patients with type 32C. Overall, the mean age was 67+/- 23.62 (Mean+/-SD) years. Follow up period was 12+/-6.92 (Mean+/-SD) months. At the time of follow-up, fractures in 25 patients had united and the remaining patients were proceeding to union. Average time to union was 4.0+/-1.48(Mean+/- SD) months. Conclusion: LISS technique can achieve 100% union rate in both acute distal femoral and periprosthetic fractures. Most fractures proceed to union without the need for primary bone grafting and there were no deep infections, thromboembolic events, persistent pain or malunion. However, the procedure requires careful planning and experience in the operative technique.
The clinical and radiological outcomes of the LISS plate for distal femoral fractures: A systematic review. Injury. 2009 May 30. UK PURPOSE: The purpose of this systematic review was to assess the literature evaluating the clinical and radiological outcomes following less invasive surgical stabilisation system (LISS) fixation of distal femoral fractures (AO 32/33). METHODS: A review of EMBASE, Medline, CINAHL and AMED from their inception to November 2008, sources of grey literature and a pertinent hand search of specialist orthopaedic journals was undertaken. RESULTS: Twenty- one studies assessing 663 patients with 694 fractures were reviewed. The findings suggest that the LISS system may be an appropriate fixation method for the management of distal femoral fractures. However, there remains a high incidence of loss of reduction (n=134; 19%), delayed or non-union (n=40; 6%) and implant failure (n=38; 5%). On analysis, such complications were largely confined to articles published before 2005, therefore during the infancy of the widespread clinical application of this trauma system. On critical appraisal, the evidence-base remains limited by recruiting small, under-powered sample sizes and poorly accounting for confounding variables such as osteoporosis, diabetes, multi-trauma and fracture classification. CONCLUSION: Further study is required to assess the outcomes of LISS fixation in specific patient populations, and to compare the outcome of this fixation method to condylar plates and intrameduallary devices, to determine the optimal management strategy for this complex patient group.