Results of polyaxial locked-plate fixation of periarticular fractures of the knee. Surgical technique

Analysis of 101 Mechanical Failures in Distal Femur Fractures Treated with 3 Generations of Precontoured Locking Plates

OBJECTIVES

To evaluate mechanical treatment failure in a large patient cohort sustaining a distal femur fracture treated with a distal femoral locking plate (DFLP).

DESIGN

This retrospective case-control series evaluated mechanical treatment failures of DFLPs.

SETTING

The study was conducted at 8 Level I trauma centers from 2010 to 2017.

PATIENTS AND PARTICIPANTS

One hundred one patients sustaining OTA/AO 33-A and C distal femur fractures were treated with DFLPs that experienced mechanical failure.

INTERVENTION

The intervention included the treatment of a distal femur fracture with a DFLP, affected by mechanical failure (implant failure by loosening or breakage).

MAIN OUTCOME MEASURE

The main outcome measures included injury and DFLP details; modes and timing of failure were studied.

RESULTS

One hundred forty-six nonunions were found overall (13.4%) including 101 mechanical failures (9.3%). Failures occurred in different manners, locations, and times depending on the DFLPs. For example, 33 of 101 stainless steel (SS) plates (33%) failed by bending or breaking in the working length, whereas no Ti plates failed here ( P < 0.05). Eleven of 12 failures with titanium-Less Invasive Stabilization System (92%) occurred by lost shaft fixation, mostly by the loosening of unicortical screws (91%). Sixteen of 44 variable -angled-LCP failures (36%) occurred at the distal plate-screw junction, whereas only 5 of 61 other DFLPs (8%) failed this way ( P < 0.05). Distal failures occurred on average at 23.7 weeks compared with others that occurred at 38.4 weeks ( P < 0.05). Variable -angled-LCP distal screw-plate junction failures occurred earlier (mean 21.4 weeks).

CONCLUSION

Nonunion and mechanical failure occurred in 14% and 9% of patients, respectively, in this large series of distal femur fracture treated with a DFLP. The mode, location, presence of a prosthesis, and timing of failure varied depending on the characteristics of DFLP. This information should be used to optimize implant usage and design to prolong the period of stable fixation before potential implant failures occur in patients with a prolonged time to union.

LEVEL OF EVIDENCE

Economic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Biomechanical comparison of intramedullary nail and plate osteosynthesis for extra-articular proximal tibial fractures with segmental bone defect

Purpose: Proximal tibial fractures are common, but the current available internal fixation strategies remain debatable, especially for comminuted fractures. This study aimed to compare the biomechanical stability of three internal fixation strategies for extra-articular comminuted proximal tibial fractures. Methods: A total of 90 synthetic tibiae models of simulated proximal tibial fractures with segmental bone defects were randomly divided into three groups: Single lateral plating (LP), double plating (DP) and intramedullary nailing (IN). Based on the different number of fixed screws, the above three groups were further divided into nine subgroups and subjected to axial compression, cyclic loading and static torsional testing. Results: The subgroup of intramedullary nailing with five proximal interlocking screws showed the highest axial stiffness of 384.36 ± 35.00 N/mm. The LP group obtained the lowest axial stiffness performance with a value of 96.59 ± 16.14 N/mm. As expected, the DP group offered significantly greater biomechanical stability than the LP group, with mean static axial stiffness and mean torque increasing by approximately 200% and 50%, respectively. According to static torsional experiments, the maximum torque of the DP subgroup was 3,308.32 ± 286.21 N mm, which outperformed all other groups in terms of torsional characteristics. Conclusion: Utilizing more than four distal screws did not provide improved biomechanical stability in the LP or DP groups, while a substantial increase in the biomechanical stability of DP was obtained when an additional medial plate was used. For the intramedullary nailing group, increasing the number of proximal interlocking screws could significantly improve biomechanical stability, and the intramedullary nailing with three proximal interlocking screws had similar static and cyclic stiffness as the DP group. The intramedullary nailing with five proximal screws had better axial stability, whereas DP had better torsional stability.

The Epidemiology of Adult Distal Femoral Shaft Fractures in a Central London Major Trauma Centre Over Five Years

Background:

Distal femoral fractures account for 3-6% of adult femoral fractures and 0.4% of all fractures and are associated with significant morbidity and mortality rates. As countries develop inter-hospital trauma networks and adapt healthcare policy for an aging population there is growing importance for research within this field.

Methods:

Hospital coding and registry records at the central London Major Trauma Center identified 219 patients with distal femoral shaft fractures that occurred between December 2010 and January 2016. CT-Scans were reviewed resulting in exclusion of 73 inappropriately coded, 10 pediatric and 12 periprosthetic cases. Demographics, mechanism of injury, AO/OTA fracture classification and management were analyzed for the remaining 124 patients with 125 fractures. Mann Whitney U and Chi Squared tests were used during analyses.

Results:

The cases show bimodal distribution with younger patients being male (median age 65.6) compared to female (median age 71). Injury caused through high-energy mechanisms were more common in men (70.5%) whilst women sustained injuries mainly from low-energy mechanisms (82.7%) (p<0.0001). Majority of fractures were 33-A (52.0%) followed by 33-B (30.4%) and 33-C (17.6%). Ninety-two (73.6%) underwent operative management. The most common operation was locking plates (64.1%) followed by intramedullary nailing (19.6%).

Interpretation:

The epidemiology of a rare fracture pattern with variable degrees of complexity is described. A significant correlation between biological sex and mechanism of injury was identified. The fixation technique favored was multidirectional locking plates. Technical requirements for fixation and low prevalence of 33-C fractures warrant consideration of locating treatment at centers with high caseloads and experience.

Comparison of the pre-shaped anatomical locking plate of 3.5 mm versus 4.5 mm for the treatment of tibial plateau fractures

PURPOSE

Treatment of tibial plateau fractures is discussed. A retrospective comparative study of fractures treated with an anatomical locking plate of 4.5 mm or 3.5 mm. Our hypothesis is that the 3.5 mm plates give an equivalent hold of fractures with comparable results and better clinical tolerance.

METHODS

From May 2010 to October 2011, 18 patients were operated on using a 4.5-mm LCP™ anatomical plate (group A) and 20 patients received a3.5-mm LCP™ anatomical plate (group B). Groups were comparable. One fracture was open.

RESULTS

For the Group A, 14 patients had a follow up of 35.3 months and for the Group B, 16 patients had a follow up of 27 months. Mobility was comparable in both groups. The Hospital for Special Surgery (HSS) score was 86.4 versus 80.6, the Lysholm score was 83.6 versus 77 for groups A and B respectively. Consolidation was 3.25 months versus 3.35 months and mean axis was 183.1° versus 181.6° for groups A and B. Mechanical axes during revision were statistically different to the controlateral axes. One secondary displacement was noted in group A and one secondary displacement in group B. Group A had eight patients reporting discomfort with the material versus three in group B (p < 0.05).

CONCLUSION

The hypothesis is proven. In regards to the results, there is no significant difference between the two groups but the clinical tolerance was better in group B. More time is needed in the long term to better evaluate these severe fractures.

Role of navigated total knee arthroplasty for acute tibial fractures in the elderly

PURPOSE

The role of total knee arthroplasty (TKA) in acute tibial fractures with existing comminution/bone loss, osteoporosis or preexistent arthritis has been described in the literature. Many of these procedures necessitate the use of stems to off-load the component and augments/wedges to avoid overresection and hence restore the joint line. Conventional methods may not be consistently accurate in restoring the desired alignment within 3° of the anatomical axis in this complex scenario. Computer-assisted TKA has been demonstrated to reproducibly and accurately restore the mechanical axis and joint line in primary TKA. Literature review has sparse data on use of navigation in acute TKA.

METHODS

9 cases of acute tibial fractures (6 tibial plateau and 3 diaphyseal) were treated by navigated primary knee arthroplasty and followed up over 26-month duration.

RESULTS

All fractures healed without notable complications. Mean range of movement was 114°. Mean Knee Society score was 84. Out of 9 cases 5 were graded as excellent, 3 good and 1 fair. All knees were corrected to within a mean of 1.7° of the calculated mechanical axis.

CONCLUSION

Total knee arthroplasty should be considered a treatment option for acute upper tibial fractures in the elderly with coexistent knee arthritis and poor bone stock. Computer-assisted navigation aids in restoration of mechanical axis and component positioning.

Reliability of locked plating in tibial plateau fractures with a medial component

BACKGROUND

Tibial plateau fractures are notoriously difficult to manage, particularly when there is a medial or posteromedial component. We report a retrospective analysis of our experience with consecutive tibial plateau fractures including a medial component that were managed using a single lateral locking plate.

HYPOTHESIS

Tibial plateau fractures with a medial component can be effectively managed using a single lateral locking plate.

MATERIALS AND METHODS

From January 2005 to December 2008, 20 patients (ten women and ten men, mean age 47 years) were managed for tibial plateau fractures having a medial component, including five Schatzker IV, five Schatzker V, and ten Schatzker VI. One patient had an open fracture. A single lateral anatomically contoured locking compression plate (LCP™) was used with or without additional isolated screws. Mobilization was started immediately after the procedure, and non-weight-bearing was maintained for at least 6 weeks.

RESULTS

All patients were followed until healing. A final evaluation was available for 13 patients after a mean of 39.1 months (12-72); five patients were lost to follow-up and two died. Early revision was needed in one patient for 20° malreduction within the fracture site. We recorded one case each of deep vein thrombosis, superficial infection, knee stiffness, and spontaneously regressive common fibular nerve dysfunction. At final evaluation (n=13), mean range of motion was 0°/2°/130° with a mean Lysholm score of 94.1 (73-100) and a mean HSS score of 93.6 (74-99). All previously employed patients returned to work at the same level after a mean of 4.5 months. Mean healing time (n=20) was 10 weeks (6-12). Initially, articular step-offs greater than 2mm were noted in five patients. At healing, no further displacements or aggravation of articular step-offs were recorded. The reductions remained stable over time. At final evaluation (n=13), mean tibiofemoral mechanical angle was 179.7° (176-184) and no patients had evidence of osteoarthritis.

DISCUSSION

The radiological and clinical outcomes in our patients were satisfactory. A single lateral locked plate ensured stable reduction of tibial plateau fractures with a medial component. Biomechanical studies of these fractures have provided conflicting data on the stability of reduction using single plate systems. However, previously reported clinical outcomes are similar to those found in our study and support the effectiveness of favouring the use of single locking plate fixation.

LEVEL OF EVIDENCE

Level IV, noncomparative retrospective study.

Acute primary total knee arthroplasty for peri-articular knee fractures in patients over 65 years of age

Peri-articular knee fractures in osteoporotic or osteoarthritic bone present a challenge to fixation, mobilisation or non-operative management. We present a series of 15 proximal tibial and 11 distal femoral fractures treated with total knee arthroplasty at over mean follow-up period of 38.8 months. The mean age of the patients was 80 years. The choice of the implant and level of constraint was determined as per the nature of injury and preference of the surgeon dealing with the fracture. Patients were allowed rapid mobilisation with immediate full weight-bearing. Good clinical results were achieved with fracture healing, sound fixation and well-aligned flexible knees. Mean Knee Society knee score was 90.2; Knee Society function score was 35.5; Oxford Knee score was 39.5; and Short Form (SF)-36 physical function score was 37.3 and mental score 50.6. Good correlation was noted between Knee society knee score and SF-36 physical function score (Pearson's 0.76, p=0.001), suggesting that generic health would dictate the final function achieved, whilst high knee scores suggest the satisfactory results of the operation. Analogous to arthroplasty for hip fractures, this technique should be considered as a treatment option in elderly peri-articular knee fractures with osteoporosis and/or osteoarthritis.

Biplanar fixation of a locking plate in the diaphysis improves construct strength

BACKGROUND

Elevation of a locking plate over the bone surface not only supports biological fixation, but also decreases the torsional strength of the fixation construct. Biplanar fixation by means of a staggered screw hole arrangement may combat this decreased torsional strength caused by plate elevation. This biomechanical study evaluated the effect of biplanar fixation on the torsional strength of locking plate fixation in the femoral diaphysis.

METHODS

Custom titanium plates were manufactured with either a linear or staggered hole pattern to evaluate planar and biplanar fixation, respectively. Fixation strength under torsional loading was evaluated in surrogates of the femoral diaphysis representative of osteoporotic and non-osteoporotic bone. Furthermore, fixation strength was determined for plate fixation with unicortical or bicortical locking screws. Five specimens per configuration were loaded to failure in torsion to determine their strength, stiffness, and failure mode.

FINDINGS

In osteoporotic bone, biplanar fixation was 32% stronger (P=0.01) than planar fixation when unicortical screws were used and 9% stronger (P=0.02) when bicortical screws were used. In non-osteoporotic bone, biplanar fixation was 55% stronger (P<0.001) than planar fixation when unicortical screws were used and 42% (P<0.001) stronger when bicortical screws were used.

INTERPRETATION

A biplanar screw configuration improves the torsional strength of diaphyseal plate fixation relative to a planar configuration in both osteoporotic and normal bone. With biplanar fixation, unicortical screws provide the same fixation strength as bicortical screws in non-osteoporotic bone.

Periarticular fractures around the hip and knee: fix or replace?

The number of periarticular fragility fractures around the hip and knee is increasing. If surgical treatment is indicated, open reduction and internal fixation or replacement can often be viable options. In contrast to secondary replacement, the use of replacement in the acute stage might be advantageous because early rehabilitation and weightbearing can be initiated. This article describes the current literature related to internal fixation or primary replacement in periarticular fractures around the hip and knee.

The strength of polyaxial locking interfaces of distal radius plates

BACKGROUND

Currently available polyaxial locking plates represent the consequent enhancement of fixed-angle, first-generation locking plates. In contrast to fixed-angle locking plates which are sufficiently investigated, the strength of the new polyaxial locking options has not yet been evaluated biomechanically. This study investigates the mechanical strength of single polyaxial interfaces of different volar radius plates.

METHODS

Single screw-plate interfaces of the implants Palmar 2.7 (Königsee Implantate und Instrumente zur Osteosynthese GmbH, Allendorf, Germany), VariAx (Stryker Leibinger GmbH & Co. KG, Freiburg, Germany) und Viper (Integra LifeSciences Corporation, Plainsboro, NJ, USA) were tested by cantilever bending. The strength of 0 degrees, 10 degrees and 20 degrees screw locking angle was obtained during static and dynamic loading.

FINDINGS

The Palmar 2.7 interfaces showed greater ultimate strength and fatigue strength than the interfaces of the other implants. The strength of the VariAx interfaces was about 60% of Palmar 2.7 in both, static and dynamic loading. No dynamic testing was applied to the Viper plate because of its low ultimate strength. By static loading, an increase in screw locking angle caused a reduction of strength for the Palmar 2.7 and Viper locking interfaces. No influence was observed for the VariAx locking interfaces. During dynamic loading; angulation had no influence on the locking strength of Palmar 2.7. However, reduction of locking strength with increasing screw angulation was observed for VariAx.

INTERPRETATION

The strength of the polyaxial locking interfaces differs remarkably between the examined implants. Depending on the implant an increase of the screw locking angle causes a reduction of ultimate or fatigue strength, but not in all cases a significant impact was observed.