Effect of articular step-off and meniscectomy on joint alignment and contact pressures for fractures of the lateral tibial plateau

[The correct tibial slope? Comparison of measuring methods]

INTRODUCTION

From a biomechanical point of view, the tibial slope plays a significant role in relation to the loading of the ligament structures in the knee joint. Currently, there are various methods of measurement for the tibial slope, which makes it difficult to compare the measurement results obtained. These differences can be decisive factors for the indication and the extent respectively of the correction of the tibial slope. The aim of this work is to present the differences in results between the measurement methods, and to compare these with the posterior tibial slope (PTS).

METHODS

By means of a comparative analysis, six measurement techniques for the tibial slope were examined. Using six parameters (correlation coefficient, range, deviation of the average slope value, correction coefficient, difference in the corrected measurements, range of the corrected measurements), these results were compared with the PTS. In this prospective study, the PTS was measured in 107 (49 male, 58 female, age 42.6 ± 23.4 years) strictly lateral plain radiological projections of the tibia with the talocrural joint in comparison with the measurement methods according to Han, Brazier, Moore and Harvey, Pietrini and LaPrade and a supratuberosity measurement.

RESULTS

The posterior slope was observed at a mean value of 6.9° (± 8.6°). Compared with the PTS, tibial slope values were increased in 55.5 % of all measurements examined and decreased in 42.4 %. In 2 % the values were identical to those of PTS. The deviations observed were significant at up to +2.9° (± 1.7°) and -2.3° (± 1.5°) respectively in comparison with the measured PTS (p < 0.001). 25.9 % of the results showed a slope value more than 2°too high and 17.6 % one less than -2° too low. Thus, in 43 % of the results clinically relevant results that were too high or too low were observed for the tibial slope compared with the PTS (p < 0.001). The correlation analyses showed very high linear connections with PTS (p < 0.001) for all methods, from r2 = 0.88 (in Moore and Harvey) up to r2 = 0.98 (in Han). The ranges varied between 13.90° (Moore and Harvey) and 18.30° (Han).

CONCLUSION

Depending on the measurement method, the slope values obtained should be individually evaluated, in order to draw the correct clinical conclusions. In principle, the radiological assessment of the whole lower leg is essential, so that concomitant pathologies in the area of the entire tibia can be detected. In everyday clinical practice, the measurement according to Han et al., and thus a shorter X‑ray projection, makes it possible to draw optimal conclusions about the PTS. LOE: Prospective diagnostic study, Level II.

Biomechanical comparisons of plate placement for medial tibial plateau fractures (Schatzker type IV): A biomechanical study using porcine tibias

INTRODUCTION

Biomechanical studies on medial tibial plateau fractures (MTPFs) (Schatzker classification type IV) are currently few, while studies using locking plates (LPs) placed on medial proximal tibias are unavailable. Hence, we compared the biomechanical properties of plate osteosynthesis at the medial and anteromedial placements using large- and small-fragment LPs in porcine bones.

MATERIALS AND METHODS

MTPFs were internally fixed using LPs on 40 porcine tibias. Specimens were equally divided into four groups: medial placement using a large-fragment LP (LPs for the medial (LM) group), anteromedial placement using a large-fragment LP (LAM group), medial placement using a small-fragment LP (SM group), and anteromedial placement using a small-fragment LP (SAM group). The translation patterns of the constructs in each group were examined by cycling loading test (displacement and translation along the mechanical axis at 10-100, 100-500, 500-1000, 1000-1500, and 1500-2000 cycles). Then, articular gaps and step-off changes after 2000 cycles were compared among the four groups.

RESULTS

One-way analysis of variance (ANOVA) revealed no significant differences in displacement and translation during cyclic loading. One-way ANOVA followed by post hoc analysis revealed that the anterior gap was lower in LPs for the medial (LM) than in SM (P = 0.029) and SAM (P = 0.0026). The central gap was also lower in LM than in SM (P = 0.042) and SAM (P < 0.001), and it was lower in LAM than in SAM (P = 0.047). Likewise, the posterior gap was lower in LM than in LAM (P = 0.025) and SAM (P < 0.001). Furthermore, the central step-off of SAM was higher than that of LM, LAM, and SM (P < 0.001, P = 0.0014, and P = 0.0077, respectively). The posterior step-off was lower in LM than in SAM and LAM (P = 0.037 and P < 0.001), and it was also lower in SM than in SAM (P = 0.0082).

CONCLUSION

Medial LP placement for MTPFs in porcine bones resulted in significantly lower posterior step-offs after cyclic loading than anteromedial placement, and large-fragment LPs for MTPFs caused significantly lower fracture gaps in the central articular after cyclic loading than small-fragment LPs.

What factors are associated with loss of alignment after open reduction and internal fixation for tibial plateau fractures? A retrospective multicenter (TRON group) study

BACKGROUND

Tibial plateau fractures (TPFs) are one of the most challenging intra-articular fractures to treat. Along with reconstruction of the articular surfaces, appropriate alignment of the knee joints must be obtained and maintained after open reduction and internal fixation (ORIF) for TPFs because loss of alignment (LA) is associated with worse clinical outcomes. We aimed to investigate and clarify the risk factors related to LA after ORIF for TPFs.

METHODS

This multicenter, retrospective cohort study used data of hospitals of the Trauma Research Group (TRON group) from January 1, 2011, to December 31, 2020. Among 293 TPFs extracted from the database, we evaluated the alignment of the articular surface to the anatomical axis of the tibia in the immediate postoperative and last follow-up radiographs. We defined a change of alignment from the immediate postoperative radiograph as LA. We evaluated the risk factors of LA using univariate and multiple logistic regression analyses.

RESULTS

LA was observed in 27 fractures (9.2%). In multiple logistic regression analyses, preoperative articular step-off and postoperative condylar widening were statistically associated with LA (OR = 1.1, 95% CI: 1.02-1.19 and P = 0.012; OR = 1.04, 95% CI: 1.00-1.08, P = 0.045, respectively). We calculated the threshold by drawing a receiver operating characteristic curve using the final regression model. The threshold of postoperative widening was 8.2 mm. We divided the 293 TPFs into two groups according to this threshold and determined differences between the two groups using Fisher's exact test. The two groups were statistically significantly different (P = 0.00502).

CONCLUSIONS

Preoperative articular step-off and postoperative condylar widening could be associated with LA after ORIF for TPFs. We suggest that intraoperative restoration of condylar widening is important for the prevention of malalignment following ORIF for TPF.

Mismatch between Clinical-Functional and Radiological Outcome in Tibial Plateau Fractures: A Retrospective Study

BACKGROUND

The evaluation of tibial plateau fractures (TPF) encompasses the assessment of clinical-functional and radiological parameters. In this study, the authors aimed to investigate the potential correlation between these parameters by utilizing both the clinical-functional and the modified radiological Rasmussen score.

METHODS

In this retrospective monocentric study conducted at a level-I trauma center, patients who underwent surgery between January 2014 and December 2019 due to a TPF were included. The clinical-functional Rasmussen score prior to the injury, at 1-year postoperatively, and during the last follow-up (minimum 18 months) was assessed using a standardized questionnaire. Additionally, the modified radiological Rasmussen score was determined at the 1-year postoperative mark using conventional radiographs in two planes.

RESULTS

A total of 50 patients were included in this study, comprising 40% (n = 20) men, and 60% (n = 30) women, with an average age of 47 ± 11.8 years (range 26-73 years old). Among them, 52% (n = 26) had simple fractures (classified according to Schatzker I-III), while 48% (n = 24; according to Schatzker IV-VI) had complex fractures. The mean follow-up was 3.9 ± 1.6 years (range 1.6-7.5 years). The functional Rasmussen score assessed before the injury and at follow-up showed an "excellent" average result. However, there was a significant difference in the values of complex fractures compared to before the injury. One year postoperatively, both the clinical-functional score and the modified radiological score demonstrated a "good" average result. The "excellent" category was more frequently observed in the functional score, while the "fair" category was more common in the radiological score. There was no agreement between the categories in both scores in 66% of the cases.

CONCLUSIONS

The data from this retrospective study demonstrated that patients with TPF are able to achieve a nearly equivalent functional level in the medium-term after a prolonged recovery period, comparable to their pre-injury state. However, it is important to note that the correlation between clinical-functional and radiological parameters is limited. Consequently, in order to create prospective outcome scores, it becomes crucial to objectively assess the multifaceted nature of TPF injuries in more detail, both clinically and radiologically.

Influence of articular step-off on contact mechanics in fractures of the posterolateral-central tibial plateau - a biomechanical study

BACKGROUND

The posterior quadrants of the tibial plateau are frequently involved in OTA type C tibial plateau fractures. The biomechanical influence of a residual articular step-off of the posterolateral-central (PLC) segment, which is difficult to visualize intraoperatively, remains unclear. Therefore, aim of this study was to investigate the contact area and stress of the tibial plateau in cases of different articular step-offs of the PLC segment.

METHODS

Seven human cadaveric knees were used to simulate articular impressions of the PLC segment with step-offs of 1 mm, 3 mm, and 5 mm. The knees were axially loaded up to 150 N during a total of 25 dynamic cycles of knee flexion up to 90°. Pressure mapping sensors were inserted into the medial and lateral joint compartments beneath the menisci to measure articular contact area and stress.

RESULTS

Between 60° and 90° of knee flexion, increasing PLC segment impressions of the tibial plateau led to increasing contact stress and a significantly reduced contact area. The largest decrease in the contact area was 30 %, with an articular step-off of 5 mm (0.003). An increase in contact stress, especially from a 3-mm step-off, was measured, with a doubling of the mean contact stress at 3-mm and 5-mm step-offs and 90° knee flexion (p = 0.06/0.05).

CONCLUSION

From a biomechanical point of view, posterior impressions of the PLC segment greater than a 1-mm step-off should be addressed as anatomically as possible, especially in active patients with the need for higher knee flexion angles.

Influence of reduction quality on functional outcome and quality of life in the surgical treatment of tibial plateau fractures: A retrospective cohort study

BACKGROUND

Despite a substantial improvement in the operative treatment of tibial plateau fractures, the surgical procedure remains controversial and is generally challenging, as patients may develop postoperative arthritis and functional impairment of the knee joint.

HYPOTHESIS

In the surgical treatment of tibial plateau fractures the intraoperative reposition quality has the greatest influence on the postoperative outcome, whereby misalignments of≥2mm lead to a worse result.

PATIENTS AND METHODS

Forty-one patients with tibial plateau fractures were postoperatively examined. The operative treatment was performed under reduction control using an intraoperative 3D C-arm. The follow-up collective was divided into two groups depending on the intraoperative reduction result. The postoperative results were then evaluated using the following parameters: Lysholm score, Rasmussen score, Tegner score, SF-36 score, range of motion and pain level.

RESULTS

Group 1 (articular surface incongruencies<2mm) tended to achieve a better result in all scores than group 2 (articular surface incongruencies≥2mm), in the Lysholm score (p=0.039), in the comparison of the range of motion (p=0.012) and the pain level (p=0.039) this was significant. Group 1 achieved an average of 90.71 points (group 2: 78.74) in the Lysholm score. The average range of motion of the knee joint was 138.93° in group 1 (group 2: 127.78°). The average value of the current pain level in group 1 was 1.14 (group 2: 2.63).

DISCUSSION

Both study groups achieved a very good result compared to the available literature. It appears that reduction quality - which can be analyzed with intraoperative 3D imaging - plays the most important role in postoperative quality of life and functional outcome. Intraoperative adjustments of the reduction should therefore be performed on joint surface irregularities with a size above 2mm.

LEVEL OF EVIDENCE

III; retrospective case control study.

Revisiting the management of tibial plateau fractures

Three-dimensional imaging has changed the understanding and management of tibial plateau fractures. In the 1970s, Schatzker proposed a classification for tibial plateau fractures, which highlighted the morphology of the six principal types. More recently, this original classification was complimented by an extended one underscoring the importance of understanding where the split wedge fragment(s) is/are located in three dimensions. The extended classification introduced the split wedge fragment and the continuity of the rim as the determinants of joint stability and the critical role that this plays in the management of tibial plateau fractures. The current manuscript re-emphasizes contemporary concepts of tibial plateau stability and depicts key issues which must be considered when planning the definitive surgical fixation of tibial plateau fractures.

[Change in the treatment of tibial plateau fractures]

BACKGROUND

The treatment of tibial plateau fractures has experienced a number of very different conceptual developments in recent years, not only with respect to technical innovations but also against the background of changing fracture patterns and the growing requirements of patients.

OBJECTIVE

What developments in recent years have had a significant impact on current treatment strategies for tibial plateau fractures?

METHODS

Narrative review of publications listed in PubMed on the topic of treatment of complex tibial plateau fractures.

RESULTS

While the two-dimensional classifications are becoming less important, computed tomography (CT)-based three-dimensional assessment of fracture progression and an access strategy based on it are coming to the fore. Direct dorsal approaches have been shown to be superior, particularly in the case of relevant posteromedial and/or posterolateral fracture involvement. The step-by-step approach extension via specific osteotomies of ligamentous attachments also enables a needs-dependent and fracture-dependent complete joint visualization and reduction control. In the treatment of geriatric tibial plateau fractures, primary treatment with endoprostheses is becoming increasingly more important to enable early mobilization under full load bearing with significantly shorter rehabilitation times.

CONCLUSION

Modern developments in the context of fracture treatment around the tibial plateau have led to a relevant reduction of infections and improved surgical outcomes; however, the high demands and the improved understanding of fractures still underline the great challenge in the treatment of complex fracture patterns.

Biomechanical Comparison of 2 Double Plating Methods in a Coronal Fracture Model of Bicondylar Tibial Plateau Fractures

OBJECTIVES

Because management of bicondylar tibial plateau fractures are complicated even for expert surgeons, with using a coronal fracture model, we aimed to compare 2 kinds of double locked plating techniques that consisted of the lateral locking plate and the medial locking plate inserted medial anteriorly (MA-ly) or medial posteriorly (MP-ly).

METHODS

Fourteen fresh-frozen tibias stabilized with the MA or MP methods were allocated into 2 groups with similar bone mineral density values. Implanted samples were tested under incremental fatigue loading conditions using a customized load applicator. An optical motion tracking system was used to assess relative displacements and rotations of fracture fragments during loading. Static and dynamic global stiffness, failure load, failure cycles, as well as movements of fracture fragments were measured.

RESULTS

There were no significant differences between the 2 fixation methods regarding global stiffness, failure load, or failure cycles (P = 0.67-0.98, depending on the parameter). The kinematic evaluations, however, revealed that different positions of the medial locking plates altered the directions of movements for the medial-anterior or medial-posterior fracture segments.

CONCLUSIONS

The mechanical stability of tibia-implant constructs fixed with the double plating methods was not remarkably affected by the location of the medial locking plate. Depending on clinical conditions and surgeons' preferences, bicondylar tibial plateau fractures can be managed with either MA or MP methods.

A lateral fracture step-off of 2mm increases intra-articular pressure following tibial plateau fracture

INTRODUCTION

The aim of this study was to evaluate the effects of increasing posttraumatic step-offs after lateral tibial plateau fracture reduction on the intra-articular pressure.

MATERIALS AND METHODS

In eight fresh-frozen human cadaveric knees with intact menisci, a standardized sagittal osteotomy of the lateral tibial condyle was performed as an OTA/AO type 41-B1 fracture-model. The fragment was fixed by a customized sled including an angular stable tibia plate to evaluate step-offs from 0 mm to 8 mm in 1mm increments. In a servo-hydraulic testing machine, an axial force was applied to the tibial plateau in 0° (700N), 15° (700N), 30° (700N), 60° (350N), and 90 ° (350N) of flexion while the joint pressure was recorded by two pressure sensors.

RESULTS

A 1mm step-off did not result in an increased joint pressure. At 60° of flexion a 2mm step-off increased the lateral joint pressure by 61.84kPa (P = 0.0027). In 30° of flexion, a 3mm step raised the lateral joint pressure by 66.80kPa (p = 0.0017), whereas in 0°, 15° and 90° of flexion, a 4mm step increased the pressure by >50kPa (P < 0.05). Concomitant medial joint pressure increments were lower than those in the lateral plateau. A significant increase of 19-24kPa in the medial joint pressure was detected in 90° of flexion with a 1mm lateral step (P = 0.0075), in 15° and 60° of flexion with a 2mm step (P < 0.05), in 0° of flexion with a 4mm step (P = 0.0215) and in 30° of flexion with a 7mm step (P = 0.0487).

CONCLUSION

Lateral fracture step-offs of 2mm or larger should be reduced intraoperatively to avoid large increases in lateral joint pressure.

Initial displacement of the intra-articular surface after articular fracture correlates with PTA in C57BL/6 mice but not "superhealer" MRL/MpJ mice

Posttraumatic arthritis (PTA) occurs commonly after articular fracture and may arise, in part, from joint surface incongruity after injury. MRL/MpJ (MRL) "super-healer" mice are protected from PTA compared to C57BL/6 (B6) mice following articular fracture. However, the relationship between the initial displacement of the articular surface, biologic response, and susceptibility to PTA after fracture remains unclear. The objective of this study was to assess whether joint incongruity after articular fracture, as measured by in vivo micro-computed tomography (microCT), could predict pathomechanisms of PTA in mice. B6 and MRL mice (n = 12/strain) received a closed articular fracture (fx) of the left tibial plateau. Articular incongruity was quantified as bone surface deviations (BSD) for each in vivo microCT scan obtained from pre-fx to 8 weeks post-fx, followed by histologic assessment of arthritis. Serum concentrations of bone formation (PINP) and bone resorption (CTX-I) biomarkers were quantified longitudinally. Both strains showed increases in surface incongruity over time, as measured by increases in BSD. In B6 mice, acute surface incongruity was significantly correlated to the severity of PTA (R ²  = 0.988; p = .0006), but not in MRL mice (R ²  = 0.224; p = .220). PINP concentrations significantly decreased immediately post-fx in B6 mice (p = .023) but not in MRL mice, indicating higher bone synthesis in MRL mice. MRL/MpJ mice demonstrate a unique biologic response to articular fracture such that the observed articular bone surface displacement does not correlate with the severity of subsequent PTA. Clinical Relevance: Identifying therapies to enhance acute biologic repair following articular fracture may mitigate the risk of articular surface displacement for PTA.

Posterior tibial slope of the knee measured on X-rays in a Turkish population

PURPOSE

Posterior tibial inclination of the knee joint should be considered during anterior cruciate ligament reconstruction and total knee replacement surgery. This inclination is called the posterior tibial slope (PTS) angle. The PTS differs among populations and the aim of this study was to determine the mean PTS in a Turkish population.

METHODS

PTS was measured retrospectively on lateral knee X-rays (n = 1024). The angle between the line connecting the anterior and posterior points of the lateral tibial plateau and the tibial longitudinal axis was taken as the PTS angle. Intra- and inter-observer agreement regarding the measurements on 20 X-rays were checked.

RESULTS

The mean PTS angle for the entire cohort was 8.36 ± 3.3° (range: 2.1-18.7°); it was 8.57 ± 3.4° (range: 2.3-17.4°) in men and 8.16 ± 3.2° (range: 2.1-18.7°) in women. Although no significant correlation was detected between PTS and age, PTS was higher in men than in women.

CONCLUSION

The increasing number of total knee replacement surgeries has increased the need for studies on implant mismatch. In this study, reference PTS values were determined for a Turkish population. It may be beneficial to use patient-specific implants in some cases.

Postoperative Dorsal Proximal Interphalangeal Joint Subluxation in Volar Base Middle Phalanx Fractures

Introduction  This study was designed to assess factors associated with postoperative dorsal proximal interphalangeal (PIP) joint subluxation after operative treatment of volar base middle phalanx fractures. Our second purpose was to study the association between postoperative dorsal subluxation with postoperative arthritis. Materials and Methods  We identified 44 surgically treated volar base PIP joint fractures with available pre- and postoperative radiographs between 2002 and 2015 at two academic medical systems with a median follow-up of 3.5 months. Demographic, injury, radiographic, and treatment data that might be associated with postoperative dorsal subluxation were collected. Three hand surgeons independently assessed subluxation and arthritis on radiographs. Bivariate analysis was performed to analyze our two study purposes. Results  Six of 44 (14%) had postoperative dorsal subluxation after initial surgery. Bivariate analysis showed no factors with statistically significant association with postoperative subluxation, assessed independently by three hand surgeons on radiographs. Fifty per cent of the joints with postoperative arthritis had postoperative subluxation compared with 21% of joints without postoperative subluxation. No significant association was found between postoperative dorsal subluxation with postoperative arthritis. Conclusion  The association of persistent subluxation and early arthrosis in dorsal PIP joint fracture dislocations needs further study. At this time, it is unclear in what ways persistent subluxation or arthrosis affects the rate of reoperation. Level of Evidence  This is a therapeutic level IV study.

Morphometric study of gender difference in osteoarthritis posterior tibial slope using three-dimensional magnetic resonance imaging

Posterior tibial slope (PTS) is an important parameter of sagittal alignment associated with postoperative stability and kinematics after total knee arthroplasty (TKA). However, data are limited regarding the innate gender differences in PTS in Koreans. The current study separately measured the PTS of the medial and lateral tibial plateau on magnetic resonance images of 511 patients with knee joint osteoarthritis who had Kellgren and Lawrence grade 3 and 4 (430 women, 81 men) and compared the measurements between and within the genders. The tibia was then rotated to the tibial plateau with the tibial centroid axis and the PTS was evaluated from best-fit planes on the surface of the proximal tibia and individually for the medial, lateral, and overall plateaus. The average overall PTS was 10.0° ± 3.5°. The average overall PTS of the female and male patients was 10.2° ± 3.4° and 8.8° ± 4.0°, respectively. The average medial PTS was 10.4° ± 4.0°, significantly greater than the mean lateral PTS of 8.7° ± 3.9° (P < 0.05). The average medial and lateral tibial slopes for female patients were 10.7° ± 3.8° and 8.8° ± 3.8°, respectively, while the average medial and lateral tibial slopes for male patients were 8.9° ± 4.8° and 7.9° ± 4.7°, respectively. The medial and overall PTS were significantly greater in female patients than in male patients (P < 0.05). The results showed a gender difference in PTS and that medial PTS was greater than lateral PTS. These findings have clinical relevance in knee reconstructive surgery for determining ideal placement of the posterior slope tibial component. Surgeons should be aware of variability and gender differences in the tibial slope of patients undergoing TKA.

Influence of reduction accuracy in lateral tibial plateau fractures on intra-articular friction - a biomechanical study

BACKGROUND

Lateral tibial split fractures (LTSF) usually require surgical therapy with screw or plate osteosynthesis. Excellent anatomical reduction of the fracture is thereby essential to avoid post-traumatic osteoarthritis. In clinical practice, a gap and step of 2 mm have been propagated as maximum tolerable limit. To date, biomechanical studies regarding tibial fractures have been limited to pressure measurement, but the relationship between dissipated energy (DE) as a friction parameter and reduction accuracy in LTSF has not been investigated. In past experiments, we developed a new method to measure DE in ovine knee joints. To determine weather non-anatomical fracture reduction with lateral gap or vertical step condition leads to relevant changes in DE in the human knee joint, we tested the applicability of the new method on human LTSFs and investigated whether the current limit of 2 mm gap and step is durable from a biomechanical point of view.

METHODS

Seven right human, native knee joint specimens were cyclically moved under 400 N axial load using a robotic system. During the cyclic motion, the flexion angle and the respective torque were recorded and the DE was calculated. First, DE was measured after an anterolateral approach had been performed (condition "native"). Then a LTSF was set with a chisel, reduced anatomically, fixed with two set screws and DE was measured ("even"). DE of further reductions was then measured with gaps of 1 mm and 2 mm, and a 2 mm step down or a 2 mm step up was measured.

RESULTS

We successfully established a measurement protocol for DE in human knee joints with LTSF. While gaps led to small though statistically significant increase (1 mm gap:ΔDE compared with native = 0.030 J/cycle, (+ 21%), p = 0.02; 2 mm gap:ΔDE = 0.032 J/cycle, (+ 22%), p = 0.009), this increase almost doubled when reducing in a step-down condition (ΔDE = 0.058 J/cycle, (+ 56%), p = 0.042) and even tripled in the step-up condition (ΔDE = 0.097 J/cycle, (+ 94%), p = 0.004).

CONCLUSIONS

Based on our biomechanical findings, we suggest avoiding step conditions in the daily work in the operating theatre. Gap conditions can be handled a bit more generously.

The effect of coronal splits on the structural stability of bi-condylar tibial plateau fractures: a biomechanical investigation

INTRODUCTION

Surgical treatment of bi-condylar tibial plateau fractures is still challenging due to the complexity of the fracture and the difficult surgical approach. Coronal fracture lines are associated with a high risk of fixation failure. However, previous biomechanical studies and fracture classifications have disregarded coronal fracture lines.

MATERIALS AND METHODS

This study aimed to develop a clinically relevant fracture model (Fracture C) and compare its mechanical behavior with the traditional Horwitz model (Fracture H). Twelve samples of fourth-generation tibia Sawbones were utilized to realize two fracture models with (Fracture C) or without (Fracture H) a coronal fracture line and both fixed with lateral locking plates. Loading of the tibial plateau was introduced through artificial femur condyles to cyclically load the fracture constructs until failure. Stiffness, fracture gap movements, failure loads as well as relative displacements and rotations of fracture fragments were measured.

RESULTS

The presence of a coronal fracture line reduced fracture construct stiffness by 43% (p = 0.013) and decreased the failure load by 38% from 593 ± 159 to 368 ± 63 N (p = 0.016). Largest displacements were observed at the medial aspect between the tibial plateau and the tibial shaft in the longitudinal direction. Again, the presence of the coronal fracture line reduced the stability of the fragments and created increased joint incongruities.

CONCLUSIONS

Coronal articular fracture lines substantially affect the mechanical response of tibia implant structures specifically on the medial side. With this in mind, utilizing a clinically relevant fracture model for biomechanical evaluations regarding bi-condylar tibial plateau fractures is strongly recommended.

How can the articular surface of the tibial plateau be best exposed? A comparison of specific surgical approaches

INTRODUCTION

The correct choice of a fracture-specific surgical approach with an articular accessibility in complex tibial plateau fractures to facilitate durable fracture fixation of the anatomic articular reconstruction is under debate, as the most important risk factor for malreduction in complex tibial plateau fractures is an impaired visualization of the articular surface.

MATERIALS AND METHODS

Six established surgical approaches were simulated on 12 cadaver knees. The visible articular surface was labeled with an electrocautery device for each approach and subsequently analyzed with ImageJ. Areas of each hemiplateau were compared using the Student's t test.

RESULTS

In the lateral tibial plateau, the dorsal 19.0 ± 5.8% of the articular surface could be exposed via the postero-lateral approach. Via the antero-lateral arthrotomy, 36.6 ± 9.4% of the anterior articular surface was visible. The additional osteotomy of the lateral femoral epicondyle significantly increased the exposure to 65.6 ± 7.7% (p < 0.001). In the medial tibial plateau, the osteotomy of the medial femoral epicondyle significantly improved visualization of the medial articular surface (62.3 ± 8.6%) compared to the postero-medial approach (14.0 ± 7.3%) and the antero-medial approach (36.9 ± 9.2%) of the articular (p < 0.001).

CONCLUSIONS

Visualization of the tibial articular surface is limited through specific surgical approaches. Extension by osteotomy of the femoral epicondyle led to a significant improvement in the articular exposure without, however, obtaining sufficient visibility of the posterior joint segments, which should be included in the preoperative strategy. The proposed surgical approach-specific map of the tibial plateau may constitute an important instrument in the toolbox of an experienced surgeon to treat complex tibial plateau fractures at the highest level.

LEVEL OF EVIDENCE

Level IV.

Surgical Management of Displaced Intra-Articular Calcaneal Fractures: What Matters Most?

Displaced intra-articular calcaneal fractures are severe, complex injuries that can cause significant long-term functional impairment. Despite the controversies of whether these fractures should be treated operatively or nonoperatively, functional improvement can be seen with confounding variables that can be controlled by the surgeon. This article reviews prognostic factors that are associated with good functional outcomes following operatively treated displaced intra-articular calcaneal fractures.

[Extended medial and extended lateral approach for tibial plateau fractures]

OBJECTIVE

Complete visualization of the articular surface in comminuted uni- or bicondylar tibial plateau fractures as a prerequisite for anatomical reconstruction to reduce the risk of posttraumatic osteoarthritis.

INDICATIONS

Unicondylar lateral or medial as well as bicondylar intra-articular tibial plateau fractures with central and/or dorsal fracture lines; comminuted destruction of the medial or lateral tibial plateau with dislocation of >2 mm.

CONTRAINDICATIONS

Critical soft tissue in the approach area, femoral condylar fracture, intraligamentous ruptures of the medial or lateral ligaments or the posterolateral corner.

SURGICAL TECHNIQUE

Medial: via the medial or anteromedial approach; lateral: via the antero- or posterolateral approach for open reduction and internal fixation of the tibial plateau fracture. Sharp dissection down to the medial/lateral ligamentous accompanying structures with subsequent presentation of the medial/lateral femoral epicondyle. Medial: approximately 2 × 2 cm osteotomy of the medial femoral epicondyle. Lateral: osteotomy of an approximately 1 × 1 × 0.5 cm bone block of the lateral femoral epicondyle either with protection or including the popliteus tendon running ventrally in the sulcus popliteus. In this case, a violation of the articular condyle should be avoided.

POSTOPERATIVE MANAGEMENT

Early functional posttreatment with full mobilization and 10-20 kg partial load bearing on forearm crutches, fracture-dependent for 6-12 weeks.

RESULTS

Very good visualization of the comminuted articular surface with postoperatively anatomical reconstruction of complex fracture patterns without postoperative concomitant instabilities.

Contribution of minimally invasive bone augmentation to primary stabilization of the osteosynthesis of Schatzker type II tibial plateau fractures: Balloon vs bone tamp

BACKGROUND

Schatzker type II tibial plateau fractures necessitate the least invasive treatment possible. Arthroscopic reduction by bone tamp followed by osteosynthesis is the current gold standard for this type of tibial plateau fracture. The objective of this study was to compare this technique to anterior approach tuberoplasty with balloon reduction. The comparison criteria were residual articular step off, metaphyseal cavity volume formed during reduction, and mechanical strength to separation and to depression displacement.

METHODS

Fractures were created on 12 human cadaveric tibiae and reduced by a minimally invasive approach in six specimens by a balloon, and by bone tamp in the six others. Articular step off and metaphyseal-epiphyseal cavity volume were measured by TDM. Mechanical tests were performed up to assembly failure to characterize structural strength. Secondary displacements, fracture depression displacement and separation were measured by optical methods.

FINDINGS

There was no significant difference in step off measurement after balloon reduction or bone tamp (0.29 cm vs 0.37 cm; p = 0.06). The cavity volume formed by balloon reduction was significantly smaller than the volume created by bone tamp reduction (0.45 cm³ vs 5.12 cm; p = 0.002). The compressive load required for assembly failure was significantly greater in the balloon group than in the bone tamp group (1210.17 N vs 624.50 N; p = 0.015).

INTERPRETATION

There exists a correlation between load to failure of the assembly frame and the metaphyseal volume required for bone fracture reduction. The minimally invasive balloon technique has fewer negative effects on the osseous stock, thereby enabling better primary structural strength of the fracture.

Evaluating the Utility of the Lateral Elbow Radiograph in Central Articular Olecranon Reduction: An Anatomic and Radiographic Study

OBJECTIVES

The surgical reduction of intra-articular olecranon fractures is judged primarily on the lateral elbow radiograph, as orthogonal imaging of the articular surface is not obtainable. We sought to determine surgeon accuracy in identifying intra-articular olecranon malreductions on the lateral elbow radiograph.

METHODS

Six human fresh-frozen cadaveric elbow specimens were sagittally sectioned in 5-mm increments after olecranon dissection, preservation of soft tissue envelope, and rigid fixation of the elbow in an external fixator. Three patterns of central intra-articular olecranon malreduction were created in each elbow using a ruler and bone saw. Perfect lateral elbow radiographs were taken of each malreduction, and these images were randomized along with x-rays of normal cadaveric olecranons. The image series was presented to 4 masked trauma-trained surgeons to determine whether the olecranon was malreduced or anatomic. Surgeons interpreted the same image series on 2 separate occasions separated by 6 weeks. Percent correct was recorded, and the interobserver and intraobserver reliability was calculated.

RESULTS

Orthopedic trauma surgeons correctly identified olecranon malreductions only 73% of the time on the lateral elbow radiograph. Interobserver agreement was moderate for the first review of images and fair for the second review, with respective Fleiss Kappa values of 0.43 and 0.28. Intrarater reliability revealed moderate agreement with Cohen's Kappa value ranging from 0.56 to 0.66.

CONCLUSIONS

Intra-articular olecranon malreductions are inconsistently recognized by trauma surgeons on the lateral elbow radiograph. Therefore, articular incongruity may still be present after surgical fixation of comminuted olecranon fractures. We must further define the radiographic anatomic representation of the articular olecranon to improve surgical reduction and clinical outcomes.

Complex Tibial Plateau Fractures Treated by Hybrid External Fixation System: A correlation of followup computed tomography derived quality of reduction with clinical results

BACKGROUND

Tibial plateau fractures are common due to high energy injuries. The principles of treatment include respect for the soft tissues, restoring the congruity of the articular surface and reduction of the anatomic alignment of the lower limb to enable early movement of the knee joint. There are various surgical fixation methods that can achieve these principles of treatment. Recognition of the particular fracture pattern is important, as this guides the surgical approach required in order to adequately stabilize the fracture. This study evaluates the results of the combined treatment of external fixator and limited internal fixation along with the advantages using postoperative computed tomography (CT) scan after implant removal. Materials and.

METHODS

55 patients with a mean age of 42 years (range 17-65 years) with tibial plateau fracture, were managed in our institution between October 2010 and September 2013., Twenty fractures were classified as Schatzker VI and 35 as Schatzker V. There were 8 open fractures (2 Gustilo Anderson 3A and 6 Gustilo Anderson 2). All fractures were treated with closed reduction and hybrid external fixation (n = 21/38.2%) or with minimal open reduction internal fixation and a hybrid system (n = 34/61.8%). After the removal of the fixators, CT-scan was programmed for all the cases, for correlation with the results. At final followup, the American Knee Society Score (AKSS) was administered.

RESULTS

All patients were evaluated with a minimum of 12 months (range 12-21 months) followup. Average time to union was 15.5 weeks (range 13-19 weeks). The postoperative joint congruity as evaluated in the postoperative CT-scan was <2 mm of articular step-off in 8 patients (14.5%), between 2 and 4 mm in 18 patients (32.7%) and over 4 mm in 29 (52.7%). The injured limb mechanical axis was restored within 5° compared to the contralateral limb in 36 cases (65%) and with an angulation >5° in 19 cases (35%). Patients with residual joint depression <3.5 mm had a 95% chance of having excellent AKSS knee score results and 80% chance of having excellent AKSS function scores. On the other hand, residual joint depression of >4.5 mm displayed a 100% chance of getting poor-fair scores both in AKSS knee and AKSS function score. The association of a postoperative mechanical axis within 5° of the contralateral limb and improved knee scores was statistically significant for the AKSS function and total scores but not for the AKSS knee score. The AKSS was negatively correlated with postoperative joint depression magnitude which was statistically significant. Only the amount of joint collapse was verified as a prognostic factor in a multivariate logistic regression analysis.

CONCLUSIONS

The postoperative CT-scan shows important information about bone healing, and an exact image of the reduction and the shaft alignment. Postoperative radiographs may have led to an underestimation of the degree of residual displacement. On the contrary, CT-scan demonstrates the exact grade of articular displacement and depending on CT-scan results one can better manage the postoperative rehabilitation.

"Fracturoscopy" is Superior to Fluoroscopy in the Articular Reconstruction of Complex Tibial Plateau Fractures-An Arthroscopy Assisted Fracture Reduction Technique

OBJECTIVE

To analyze the anatomic accuracy of fracture reduction controlled by fluoroscopy as compared with arthroscopically assisted reduction ("fracturoscopy") in patients with complex tibial plateau fractures (AO/OTA 41-C). Quality of fracturoscopy-guided reduction was checked with postoperative computed tomography.

DESIGN

Prospective observational study.

SETTING

Urban level 1 trauma center.

PATIENTS

Seventeen consecutive patients, with a complex, bicondylar tibial plateau fracture.

INTERVENTION

The intraoperative, open insertion of an arthroscope (2.4-mm or 2.8-mm optics), to visualize the articular surface and fracture reduction.

MAIN OUTCOME MEASUREMENTS

Ability to detect residual fracture depression or gap after previous open reduction under fluoroscopic guidance.

RESULTS

An open fracture reduction with fluoroscopic guidance was performed in all cases. In 7 cases, open reduction and fluoroscopy resulted in satisfactory fracture reduction (fluoroscopy group). In 10 of 17 cases, subsequent "fracturoscopy" showed persistent fracture depression (≥2 mm, fracturoscopy group) with the need for intraoperative correction. Patients in the fracturoscopy group demonstrated significantly greater preoperative fragment depression (12.55 ± 6.56 mm) and a larger preoperative fracture gap (7.83 ± 5.49 mm) compared with patients with a satisfactory reduction under fluoroscopy (depression 4.97 ± 4.02 mm, P = 0.016; gap 2.47 ± 1.07 mm, P = 0.023). Fluoroscopy was not successful in achieving satisfactory reduction in cases in which the postero-latero-central region was affected (P = 0.004, χ test). Postoperative computed tomography demonstrated satisfactory articular reconstruction in all cases.

CONCLUSIONS

Intraoperative fracturoscopy permitted a significantly improved visualization of fracture fragment displacement, specifically in the postero-latero-central region of the tibial plateau, as compared with fluoroscopy. Fracturoscopy is recommended for fractures involving the postero-latero-central region of the tibial plateau.

LEVEL OF EVIDENCE

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

Dance between biology, mechanics, and structure: A systems-based approach to developing osteoarthritis prevention strategies

Osteoarthritis (OA) is a leading cause of human suffering and disability for which disease-modifying treatments are lacking. OA occurs through complex and dynamic interplays between diverse factors over long periods of time. The traditional research and clinical focus on OA, the end stage disease, obscured understanding pathogenesis prior to reaching a common pathway defined by pain and functional deficits, joint deformity, and radiographic changes. To emphasize disease modification and prevention, we describe a multi-disciplinary systems-based approach encompassing biology, mechanics, and structure to define pre-osteoarthritic disease processes. Central to application of this model is the concept of "pre-osteoarthritis," conditions where clinical OA has not yet developed. Rather, joint homeostasis has been compromised and there are potentially reversible markers for heightened OA risk. Key messages from this perspective are (i) to focus research onto defining pre-OA through identifying and validating biological, mechanical, and imaging markers of OA risk, (ii) to emphasize multi-disciplinary approaches, and (iii) to propose that developing personalized interventions to address reversible markers of OA risk in healthy joints may be the key to prevention. Ultimately, a systems-based analysis of OA pathogenesis shows potential to transform clinical practice by facilitating development and testing of new strategies to prevent or delay the onset of osteoarthritis.

Can the tibial slope be measured on lateral knee radiographs?

PURPOSE

The posterior tibial slope influences both the natural knee stability as well as the stability and kinematics after total knee arthroplasty (TKA). Exact definition of the posterior tibial slope (PTS) requires lateral radiographs of the lower limb. Only lateral knee radiographs are routinely obtained after TKA, however. The purpose of the present study therefore was to analyse the relationship between PTS measurement results on short and expanded lateral knee radiographs.

METHODS

The PTS was measured on 100 consecutive lateral radiographs of the lower limb using the mechanical and three diaphyseal axes with various distances below the tibial plateau.

RESULTS

Significant differences between PTS results were found for all three diaphyseal axes, with the smallest differences and the strongest correlation for a diaphyseal axis at 16 and 20 cm below the tibial plateau. Using short distances below the tibial plateau (6 and 10 cm) resulted in an overestimation of the PTS of 3°, on average.

CONCLUSION

The PTS measurements in long lateral knee radiographs are more accurate compared to short radiographs. On short lateral knee radiographs, only a estimation of the PTS can be carried out.

LEVEL OF EVIDENCE

Diagnostic study, Level II.

Importance of Material Properties and Porosity of Bone on Mechanical Response of Articular Cartilage in Human Knee Joint—A Two-Dimensional Finite Element Study

Mechanical behavior of bone is determined by the structure and intrinsic, local material properties of the tissue. However, previously presented knee joint models for evaluation of stresses and strains in joints generally consider bones as rigid bodies or linearly elastic solid materials. The aim of this study was to estimate how different structural and mechanical properties of bone affect the mechanical response of articular cartilage within a knee joint. Based on a cadaver knee joint, a two-dimensional (2D) finite element (FE) model of a knee joint including bone, cartilage, and meniscus geometries was constructed. Six different computational models with varying properties for cortical, trabecular, and subchondral bone were created, while the biphasic fibril-reinforced properties of cartilage and menisci were kept unaltered. The simplest model included rigid bones, while the most complex model included specific mechanical properties for different bone structures and anatomically accurate trabecular structure. Models with different porosities of trabecular bone were also constructed. All models were exposed to axial loading of 1.9 times body weight within 0.2 s (mimicking typical maximum knee joint forces during gait) while free varus–valgus rotation was allowed and all other rotations and translations were fixed. As compared to results obtained with the rigid bone model, stresses, strains, and pore pressures observed in cartilage decreased depending on the implemented properties of trabecular bone. Greatest changes in these parameters (up to −51% in maximum principal stresses) were observed when the lowest modulus for trabecular bone (measured at the structural level) was used. By increasing the trabecular bone porosity, stresses and strains were reduced substantially in the lateral tibial cartilage, while they remained relatively constant in the medial tibial plateau. The present results highlight the importance of long bones, in particular, their mechanical properties and porosity, in altering and redistributing forces transmitted through the knee joint.

Metal artifacts from titanium and steel screws in CT, 1.5T and 3T MR images of the tibial Pilon: a quantitative assessment in 3D

Radiographs are commonly used to assess articular reduction of the distal tibia (pilon) fractures postoperatively, but may reveal malreductions inaccurately. While magnetic resonance imaging (MRI) and computed tomography (CT) are potential three-dimensional (3D) alternatives they generate metal-related artifacts. This study aims to quantify the artifact size from orthopaedic screws using CT, 1.5T and 3T MRI data. Three screws were inserted into one intact human cadaver ankle specimen proximal to and along the distal articular surface, then CT, 1.5T and 3T MRI scanned. Four types of screws were investigated: titanium alloy (TA), stainless steel (SS) (Ø =3.5 mm), cannulated TA (CTA) and cannulated SS (CSS) (Ø =4.0 mm, Ø empty core =2.6 mm). 3D artifact models were reconstructed using adaptive thresholding. The artifact size was measured by calculating the perpendicular distance from the central screw axis to the boundary of the artifact in four anatomical directions with respect to the distal tibia. The artifact sizes (in the order of TA, SS, CTA and CSS) from CT were 2.0, 2.6, 1.6 and 2.0 mm; from 1.5T MRI they were 3.7, 10.9, 2.9, and 9 mm; and 3T MRI they were 4.4, 15.3, 3.8, and 11.6 mm respectively. Therefore, CT can be used as long as the screws are at a safe distance of about 2 mm from the articular surface. MRI can be used if the screws are at least 3 mm away from the articular surface except for SS and CSS. Artifacts from steel screws were too large thus obstructed the pilon from being visualised in MRI. Significant differences (P<0.05) were found in the size of artifacts between all imaging modalities, screw types and material types, except 1.5T versus 3T MRI for the SS screws (P=0.063). CTA screws near the joint surface can improve postoperative assessment in CT and MRI. MRI presents a favourable non-ionising alternative when using titanium hardware. Since these factors may influence the quality of postoperative assessment, potential improvements in operative techniques should be considered.

Second-look arthroscopy after surgical treatment of Schatzker type II plateau fractures through the lateral submeniscal approach

MAIN PROBLEM

To evaluate cartilage healing using second-look arthroscopic examination in tibia plateau fracture patients who have undergone open reduction and internal fixation with a submeniscal approach technique.

METHODS

Between January 2007 and January 2010, we used second-look arthroscopy during 18-24-month follow-up of 20 patients with Schatzkar type II tibial plateau fractures who had undergone open reduction and internal fixation with a submeniscal approach technique. We classified patients according to step-off, knee range of motion, and Knee Society Score, and compared the results with those obtained by arthroscopy.

RESULTS

Radiologically, 16 cases (80 %) were reduced within 2 mm of step-off. In 11 of these cases, according to the Outerbridge classification, we checked for chondromalacia from grade II to III. We observed 2 mm of step-off in four cases, and each had chondromalacia of at least grade III. The Knee Society Score was associated with chondromalacia grade (p < 0.05).

CONCLUSION

Even in patients with normal joint range of motion and good clinical and radiological results, the actual condition of the articular cartilage varied significantly. Therefore, more long-term and regular follow-up is needed for proximal plateau fractures.

A comparative biomechanical study for complex tibial plateau fractures: nailing and compression bolts versus modern and traditional plating

AIM

To compare the biomechanical properties of a newly proposed technique, utilizing intramedullary nailing and compression bolts, for the osteosynthesis of intra-articular proximal tibial fractures with meta-diaphyseal comminution, with modern and conventional plating techniques.

METHODS

Fifteen left tibia 4th generation composite Sawbones models (in 3 groups of 5 for each technique) with identically reproduced type VI Schatzker tibial plateau fractures, including meta-diaphyseal dissociation, were used. Three different techniques of osteosynthesis were tested: (a) a new technique that combines intramedullary nailing and compression bolts, (b) internal fixation with a single lateral locking plate and (c) internal fixation with dual buttress plating technique. The model-device constructs were successively subjected to 500N, 1000N and 1500N load levels with five cycles applied at each level on both articular compartments and a final load cycle to failure. Four parameters were recorded for each technique: the average reversible or irreversible displacement in vertical subsidence, the horizontal diastasis of the intra-articular fracture, the average passive construct stiffness and the load to failure.

RESULTS

The new intramedullary nailing technique provided rigid intra-articular osteosynthesis being statistically similar to dual buttress plating for subsidence at medium and higher load levels. At the same time the proposed technique provided statistically equivalent stiffness values to the single lateral locking plate incarnating the rational of biologic fixation. Average load to failure was 1611N for single lateral locking plates, 2197N for intramedullary nailing and 4579N for dual buttress plating. The single lateral locking plate technique had the worse results in interfragmentary displacement while dual buttress plating was superior in stiffness from the other 2 techniques. The mode of failure differed between techniques, with collapse of medial plateau occurring exclusively in the single lateral locking plates group.

CONCLUSION

The proposed new technique of intramedullary nailing and compression bolts demonstrates a flexural behaviour similar to single lateral locking plates, which complies with the terms and benefits of biological fixation, while at the same time maintains a rigid intra-articular stability similar to the stiff dual buttressing plating technique.

Effect of the lower limb rotational alignment on tibiofemoral contact pressure

PURPOSE

The effect of the rotational alignment of lower extremities on the tibiofemoral contact mechanics is not known. This study was designed to measure the contact area and pressure within medial and lateral tibiofemoral compartments following controlled serial rotational deformities through femoral and tibial shafts.

METHODS

Eight lower extremities of fresh frozen cadavers were used. Computed tomography was conducted to measure the rotational profile of the lower extremities. Through a medial parapatellar arthrotomy, pressure sensors were implanted into both tibiofemoral compartments. Femoral and tibial mid-shaft osteotomies were performed and stabilized by non-locked intramedullary nails and external fixators in neutral rotation. The contact area and pressure were measured under axial loading in neutral rotation and following serial malrotations from 40° external to 40° internal malrotation in 10° increments.

RESULTS

Contact area was not affected by malrotations. Medial compartment contact pressure rose with external and decreased with internal malrotations whether femoral or tibial (P < 0.0001) while lateral pressure was not affected. When correlated with the cadavers' original rotational profile, decreased femoral neck anteversion was associated with increased medial pressure up to 28.5% at 20° of retroversion while it decreased with increased anteversion. On the other hand, decreased tibial torsion angle was associated with decreased medial pressure up to -32% at 10° of internal torsion and it increased with excessive external torsion. Furthermore, there was a strong positive correlation with the total rotational alignment as measured by the neck malleolar angle.

CONCLUSION

A significant interaction could be detected between the rotational alignment of the lower extremity and medial tibiofemoral compartment contact pressures.

Creep behavior of the intact and meniscectomy knee joints

The mechanical functions of the menisci may be partially performed through the fluid pressurization in articular cartilages and menisci. This creep behavior has not been investigated in whole knee joint modeling. A three-dimensional finite element knee model was employed in the present study to explore the fluid-flow dependent creep behaviors of normal and meniscectomy knees. The model included distal femur, tibia, fibula, articular cartilages, menisci and four major ligaments. Articular cartilage or meniscus was modeled as a fluid-saturated solid matrix reinforced by a nonlinear orthotropic and site-specific collagen network. A 300 N compressive force, equal to half of body weight, was applied to the knee in full extension followed by creep. The results showed that the fluid pressurization played a substantial role in joint contact mechanics. Menisci bore more loading as creep developed, leading to decreased stresses in cartilages. The removal of menisci not only changed the stresses in the cartilages, which was in agreement with published studies, but also altered the distribution and the rate of dissipation of fluid pressure in the cartilages. The high fluid pressures in the femoral cartilage moved from anterior to more central regions of the condyles after total meniscectomy. For both intact and meniscectomy joints, the fluid pressure level remained considerably high for thousands of seconds during creep, which lasted even longer after meniscectomy. For the femoral cartilage, the maximum principal stress was generally in agreement with the fiber direction, which indicated the essential role of fibers in load support of the tissue.

Lateral ankle radiographs: do we really understand what we are seeing?

OBJECTIVES

To evaluate the validity of using lateral intraoperative fluoroscopic imaging to assess the reduction of the tibial plafond articular surface, two hypotheses were tested: 1) the distal tibial subchondral shadow on the lateral ankle radiograph is created equally by the medial, central, and lateral portions of the distal tibia; and (2) displacement of a 5-mm width osteochondral fragment is consistently recognizable on lateral fluoroscopic imaging.

METHODS

Six human fresh-frozen tibial plafond cadaveric specimens were sagitally sectioned in 5-mm increments after removal of the anterior soft tissue and stabilization of the position of the ankle through external fixation. To test the first hypothesis, a perfect lateral radiograph was taken after sectioning the specimens. The sagittal sections were then removed sequentially from medial to lateral. A perfect lateral radiograph was taken after each change. The sagittal sections were then removed beginning laterally and moving medially. A perfect lateral radiograph was taken after each change. The images were then compared with specific evaluation of the change in the subchondral shadow density. To test the second hypothesis, three malreductions were created by displacing a 5-mm osteochondral segment. After each malreduction, a perfect lateral radiograph was saved. These saved fluoroscopic images were placed in random order with lateral images of normal specimens. Four experienced ankle surgeons were then asked to determine whether the radiographs revealed displacement. Inter- and intraobserver reliability was then evaluated.

RESULTS

First, the subchondral shadow of the distal tibia appears to be created by an equal confluence of the subchondral bone of the medial, central, and lateral aspects of the tibial plafond. Second, fellowship-trained observers experienced in pilon fracture treatment correctly identified malreduction only 45% of the time. Intraclass correlation coefficient revealed very poor interobserver reliability with an alpha reliability statistic of 0.183. Intraobserver reliability across all four observers yielded an alpha statistic of 0.474, indicating inconsistencies in observers' evaluation of identical images at separate viewings.

CONCLUSIONS

It is difficult to discern rotational or translational displacement of a 5-mm osteochondral fragment on a perfect lateral fluoroscopic view of the ankle. Even with what appears to be a perfect lateral fluoroscopic view intraoperatively, displacement may still be present. When small osteochondral fragments are present, direct visualization of the articular surface is necessary to confidently establish that an anatomic reduction has been achieved.

Articular step-off and risk of post-traumatic osteoarthritis. Evidence today

The goal of treatment in intra-articular fractures is to obtain anatomical restoration of the articular surface and stable internal fixation. Studies have attempted to specify how accurately an articular fracture needs to be reduced to minimise the chances of a poor clinical outcome. In this study, the current evidence with regard to articular step-offs and risk of post-traumatic osteoarthritis (POA) is evaluated. A literature review based on pre-specified criteria, revealed 36 articles for critical analysis related to intra-articular injuries of distal radius, acetabulum, distal femur and tibial plateau.In the distal radius, step-offs and gaps detected with precise measurement techniques have been correlated with a higher incidence of radiographic POA, but in the second 5 years after injury, a negative clinical impact of these radiographic changes has not been convincingly demonstrated. Restoring the superior weight-bearing dome of the acetabulum to its pre-injury morphology decreases POA and improves patient outcomes. Involvement of the posterior wall, however, seems to bean adverse prognostic sign. This effect may be independent of articular reduction. In the tibial plateau, articular incongruities appear to be well tolerated, and factors only partially related to articular reduction are more important in determining outcome than articular step-off alone;these include joint stability, retention of the meniscus, and coronal alignment. Based on observational approach and evaluation of the studies, factors other than just the extent of articular displacement affect the management of articular fractures. Different joints and even different areas of the same joint appear to have different tolerances for post-traumatic articular step-offs.

Hybrid external fixation in treatment of proximal tibial fractures: a good outcome in AO/ASIF type-C fractures

INTRODUCTION

The treatment of proximal tibial fractures is often challenging, and internal fixation is occasionally associated with problems in wound healing due to frequently co-existing soft tissue injuries. External fixation of these fractures have yielded satisfactory results, but some studies have reported problems in the achievement and maintenance of fracture reduction. The purpose of the present study was to evaluate the performance of a hybrid external fixator in the treatment of different types of proximal tibial fractures.

MATERIALS AND METHODS

Thirty-three proximal tibial fractures, of which 20 were high energetic, were treated with a hybrid external fixator (Tenxor Strker-Howmedica) in the acute phase. Fracture categorisation was done according to AO/ASIF, and the reduction was performed most often by closed means or through mini-open reduction (26/78.8%). The patients were followed up to an average of 12.7 months (range 10-22) and were evaluated with radiographs and clinical examinations.

RESULTS

Five AO/ASIF type-C intraarticular fractures had a poor postoperative reduction, and were thus treated with internal fixation in a second operation. Of the remaining 28 patients, local and transient pin tract infection was observed in seven patients, and one had septic arthritis of the knee. All 13 C1 and five of six C2/C3 fractures united in mean time of 15.1 weeks, whereas three of nine type-A fractures failed to unite, albeit an adequate reduction, and needed a second operation (odds ratio 11.4, 95% CI 1.0-143, compared with type-C fractures). For the remaining six type-A fractures, the mean healing time was 24 weeks (mean difference 8.9, 95% CI 6-12 weeks compared with type-C fractures). Age over 48 and the presence of an open fracture, but not fracture type, gender, or the level of injury energy, correlated to a poor subjective outcome.

CONCLUSIONS

The hybrid external fixation method we have used is safe, and type-C1 fractures are particularly suitable to be treated with this method. However, even C2/C3 fractures may be candidates for this method, but a meticulous fracture reduction should be performed. Type-A fractures are liable to healing problems when the fixator is used as a rigid complex.

A biomechanical comparison of three different lateral tibia locking plates

The purpose of this study was to determine how well laterally placed modern tibia locking plates used in the treatment of Schatzker V tibial plateau fractures would uphold the medial plateau during axial loading. Fifteen third generation Sawbone tibias were obtained and an osteotomy was cut beneath the medial plateau to recreate Schatzker V type plateau fractures. Three groups were created (n=5 per group). Each group was plated with either a Synthes 4.5-mm LCP proximal tibial plate, a Zimmer NCB proximal tibia plate, or a DePuy Polyax tibial plate. A vertical load was applied over the medial plateau using an Instron servohydraulic test machine. Load measurements were analyzed at 2 and 3 mm of subsidence as well as load to failure. Failure was defined as closure of the wedge osteotomy or the medial condyle collapsing. A statistical difference was noted between the 2 plates from Synthes and DePuy and the plate from Zimmer with load carried at 2 and 3 mm of subsidence (Synthes 640.4 N & 943.7 N, Depuy 607.4 N & 891.0 N, Zimmer 459.7 N & 643.2 N). At failure, DePuy (2051.2 N) was statistically stronger than both Synthes (1724.8 N) and Zimmer (1724.8 N). The Synthes and DePuy plates both held up better than the Zimmer plate at 2 and 3 mm of subsidence. Despite this fact, all plates tested held up well above physiological forces of full and partial weight bearing and therefore would be appropriate for the treatment of Schatzker V type tibial plateau fractures.

The combined effect of frontal plane tibiofemoral knee angle and meniscectomy on the cartilage contact stresses and strains

Abnormal tibiofemoral alignment can create loading conditions at the knee that may lead to the initiation and progression of knee osteoarthritis (OA). The degenerative changes of the articular cartilage may occur earlier and with greater severity in individuals with abnormal frontal plane tibiofemoral alignment who undergo a partial or total meniscectomy. In this investigation, subject specific 3D finite element knee models were created from magnetic resonance images of two female subjects to study the combined effect of frontal plane tibiofemoral alignment and total and partial meniscectomy on the stress and strain at the knee cartilage. Different amounts of medial and lateral meniscectomies were modeled and subject specific loading conditions were determined from motion analysis and force platform data during single-leg support. The results showed that the maximum stresses and strains occurred on the medial tibial cartilage after medial meniscectomy but a greater percentage change in the contact stresses and strains occurred in the lateral cartilage after lateral meniscectomy for both subjects due to the resultant greater load bearing role of the lateral meniscus. The results indicate that individual's frontal plane knee alignment and their unique local force distribution between the cartilage and meniscus play an important role in the biomechanical effects of total and partial meniscectomy.

Treatment of bicondylar tibia plateau fractures using locked plating versus external fixation

Bicondylar tibial plateau fractures can be difficult to treat due to the extent of articular cartilage, metaphyseal bone, and soft tissue injury. The purpose of this study was to compare the outcomes of open reduction and locked plating vs fine-wire external fixation of 58 consecutive bicondylar tibial plateau fractures at a level I trauma center. All bicondylar tibial plateau fractures were classified as Schatzker V/VI or AO/OTA type 41C. Twenty-eight patients in one group were treated using a locked plating system, and 30 patients in another group were treated with a hybrid or circular external fixation frame. The 2 groups were similar demographically. When compared with external fixation, locked plating was associated with a decreased time to union (5.9 vs 7.4 months), decreased incidence of articular malunion (7% vs 40%; P=.003), decreased knee stiffness (4% vs 13%), and decreased overall complications (27% vs 48%). The Schatzker VI subgroup accounted for 25 of the 27 complications (93%) in the locked plating group and 40 of the 48 complications (83%) in the external fixation group. We reserve the use of external fixation devices in the treatment of tibial plateau fractures to span the fracture site until the patient is amenable to definitive fixation with locked plating.

Novel measurement technique of the tibial slope on conventional MRI

The posterior inclination of the tibial plateau, which is referred to as posterior tibial slope, is determined routinely on lateral radiographs. However, radiographically, it is not always possible to reliably recognize the lateral plateau, making a separate assessment of the medial and lateral plateaus difficult. We propose a technique to measure the plateaus separately by defining a tibial longitudinal axis on a conventional MRI. The medial plateau posterior tibial slope obtained from radiographs was compared with MR images in 100 consecutive patients with knee pain when ligament or meniscal injury was assumed. The posterior tibial slope on MRI correlated with those on radiographs. The mean posterior tibial slope was 3.4 degrees smaller on MRI compared with radiographs (4.8 degrees +/- 2.4 degrees versus 8.2 degrees +/- 2.8 degrees , respectively). The reproducibility was slightly better on radiographs than MRI (+/- 0.9 degrees versus +/- 1.4 degrees ). Twenty-one of the 100 cases had more than a 5 degrees difference (range, -8.7 degrees to 8.9 degrees ) between the medial and lateral plateaus. The proposed technique allows measurement of the posterior tibial slope of the medial and lateral plateaus on a standard knee MRI. By using this novel measurement technique, a reliable assessment of the medial and lateral tibial plateaus is possible.

LEVEL OF EVIDENCE

Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Improved intra-operative reduction control using a three-dimensional mobile image intensifier - a proximal tibia cadaver study

This study aimed to analyse whether the precision of a three-dimensional mobile image intensifier (ISO-C 3D) differs from conventional two-dimensional fluoroscopy and high resolution CT scan in a fracture model of the proximal tibia. A depression fracture of the medial plateau (AO/OTA 41-B2.3) was created in 12 formalin-fixed, human cadaver knees. The cartilage of the depression could be positioned above (+1mm, +2mm), below (-1mm, -2mm), or in line with the joint surface. Fluoroscopy, computed tomography (CT) scans, and ISO-C 3D scans (four different protocols: 100 images, 66 images, 50 images, and 33 images) were done for each fracture level. Three independent observers assessed each imaging set. The difference between the estimated reduction and the real reduction was used for statistical analysis. Our hypothesis was that no differences in the precision exist between the imaging techniques (p<0.05). The conventional image intensifier group (0.7 mm+/-0.67) showed significantly higher deviations than the CT group (0.3 mm+/-0.43; p<0.001) and significantly higher deviations than all ISO-C 3D groups (0.4-0.5 mm; p<0.001). Of the ISO-C 3D groups, only the scan protocol with the lowest number of images (0.5 mm+/-0.51) showed significantly lower precision than the CT group (p<0.001). It was concluded that the three-dimensional mobile image intensifier showed higher precision in reduction assessment in a fracture model of the tibial plateau compared to fluoroscopy. High resolution CT scans should remain the standard for post-operative assessment of reduction outside the operating theatre.

Arthroscopically assisted treatment for Schatzker type I-V tibial plateau fractures

OBJECTIVE

To report the clinical outcome of arthroscopically assisted treatment for tibial plateau fractures.

METHODS

A total of 39 patients with tibial plateau fractures were treated by arthroscopic fixation from February 2002 to December 2005, including 11 patients with bony avulsion of the anterior cruciate ligament and 19 with meniscal injury. There were 4 cases of type I fracture, 12 type II, 9 type III, 12 type IV and 2 type V according to Schatzker criteria. Firstly, the combined injuries were treated. Then the plateau fractures with the displacement over 3 mm or more were reduced and fixed. Finally, the internal fixation was observed by X-ray equipment. Postoperative management was early motion and delayed weight bearing.

RESULTS

All the fractures healed in 3 or 4 months. All patients were followed up for 1 to 5 years after operation. No case had severe complications, such as poor wound healing, infection, osteofascial compartment syndrome and osteoarthritis. According to the Rasmussen scoring system, 36 cases obtained excellent or good results and the other 3 cases had moderate clinical results. The average score was 26+/-3.

CONCLUSIONS

As an adjuvant treatment of intraarticular fractures such as tibial plateau fracture, arthroscopy has many advantages. It can treat associated intraarticular soft tissue components, visualize the chondral surface reduction, lavage the hematoma and smaller loose fragments, decrease soft tissue dissection, reduce the risk of scarring and promote rapid recovery.

Operative treatment of ipsilateral noncontiguous unicondylar tibial plateau and shaft fractures: combining plates and nails

Unicondylar plateau fractures with ipsilateral noncontiguous tibial shaft fractures are rare injuries; over a 10-year period, we identified only 50 of these combined injuries in our series of 1586 tibial fractures. Modern locking plates and percutaneous techniques have been increasingly indicated for this injury pattern though this technique can compromise optimal fixation of the plateau and/or shaft fractures. For a number of years, we have combined intramedullary nails and plates for the treatment of these fractures with excellent results. With careful attention to some technical points, ipsilateral tibial plateau and shaft fractures can be managed successfully by combining 2 familiar techniques commonly employed for each injury in isolation.

Intraoperative cone-beam CT for image-guided tibial plateau fracture reduction

OBJECTIVES

A mobile isocentric C-arm was modified in our laboratory in collaboration with Siemens Medical Solutions to include a large-area flat-panel detector providing multi-mode fluoroscopy and cone-beam CT (CBCT) imaging. This technology is an important advance over existing intraoperative imaging (e.g., Iso-C(3D)), offering superior image quality, increased field of view, higher spatial resolution, and soft-tissue visibility. The aim of this study was to assess the system's performance and image quality in tibial plateau (TP) fracture reconstruction.

METHODS

Three TP fractures were simulated in fresh-frozen cadaveric knees through combined axial loading and lateral impact. The fractures were reduced through a lateral approach and assessed by fluoroscopy. The reconstruction was then assessed using CBCT. If necessary, further reduction and localization of remaining displaced bone fragments was performed using CBCT images for guidance. CBCT image quality was assessed with respect to projection speed, dose and filtering technique.

RESULTS

CBCT imaging provided exquisite visualization of articular details, subtle fragment detection and localization, and confirmation of reduction and implant placement. After fluoroscopic images indicated successful initial reduction, CBCT imaging revealed areas of malalignment and displaced fragments. CBCT facilitated fragment localization and improved anatomic reduction. CBCT image noise increased gradually with reduced dose, but little difference in images resulted from increased projections. High-resolution reconstruction provided better delineation of plateau depressions.

CONCLUSION

This study demonstrated a clear advantage of intraoperative CBCT over 2D fluoroscopy and Iso-C(3D) in TP fracture fixation. CBCT imaging provided benefits in fracture type diagnosis, localization of fracture fragments, and intraoperative 3D confirmation of anatomic reduction.

[Management of bicondylar fractures of the tibial plateau with unilateral fixed-angle plate fixation]

BACKGROUND

This study was initiated to evaluate early results of a locked screw plate for unilateral fixation of bicondylar fractures of the tibial plateau. Emphasis was laid on malreduction, secondary loss of reduction, union rate, and infection.

MATERIAL AND METHODS

A case series of patients with AO/ASIF 41-C type fractures treated with the less invasive stabilization system for the proximal lateral tibia (LISS PLT) were prospectively followed up until 11-13 months after surgery. Malreduction and malalignment were defined as an intra-articular step-off of 2 mm or more or as a malalignment in the frontal or sagittal plane of more than 5 degrees.

RESULTS

Sixty-eight patients with 69 fractures were involved. Fourteen fractures were open. Primary bone grafting was performed in 13 patients. Significant malreduction was seen in 16 patients. Sixty-two (91%) patients returned for follow-up. All but one fracture healed eventually. The number of infections was low (4 superficial, 1 deep). Nine patients had a significant loss of reduction. Of 54 patients outcome scores were good to excellent in 47 patients on the Lysholm score (average 87.2) and in 44 patients on the Rasmussen score (average 26.7).

CONCLUSION

We concluded that unilateral locked screw plating is a good alternative in the treatment of problematic fractures of the tibial plateau that are associated with soft tissue damage and metaphyseal comminution. The reduction technique for exact alignment is demanding.