How do orthopaedic surgeons and rehabilitation professionals interpret and assess 'toe touch' weight bearing and 'partial' weight bearing status in the rehabilitation setting?

Biomechanical testing of a computationally optimized far cortical locking plate versus traditional implants for distal femur fracture repair

BACKGROUND

This study experimentally validated a computationally optimized screw number and screw distribution far cortical locking distal femur fracture plate and compared the results to traditional implants.

METHODS

24 artificial femurs were osteotomized with a 10 mm fracture gap 60 mm proximal to the intercondylar notch. Three fixation constructs were used. (i) Standard locking plates secured with three far cortical locking screws inserted according to a previously optimized distribution in the femur shaft (n = 8). (ii) Standard locking plates secured with four standard locking screws inserted in alternating plate holes in the femur shaft (n = 8). (iii) Retrograde intramedullary nail secured proximally with one anterior-posterior screw and distally with two oblique screws (n = 8). Axial hip forces (700 and 2800 N) were applied while measuring axial interfragmentary motion, shear interfragmentary motion, and overall stiffness.

FINDINGS

Experimental far cortical locking plate results compared well to published computational findings. Far cortical locking femurs contained the highest axial motion within the potential ideal range of 0.2-1 mm and a sheer-to-axial motion ratio < 1.6 at toe-touch weight-bearing (700 N). At full weight-bearing (2800 N), Standard locking-plated femurs had the only axial motion within 0.2-1 mm but had an excess shear-to-axial motion ratio. Nail-implanted femurs underperformed at both forces.

INTERPRETATION

For toe-touch weight-bearing, the far cortical locking construct provided optimal biomechanics to allow moderate motion, which has been suggested to encourage early callus formation. Conversely, at full weight-bearing, the standard locking construct offered the biomechanical advantage on fracture motion.

Severity of Complications after Locking Plate Osteosynthesis in Distal Femur Fractures

Background: Locked plating for distal femur fractures is widely recommended and used. We systematically reviewed clinical studies assessing the benefits and harms of fracture fixation with locked plates in AO/OTA Type 32 and 33 femur fractures. Methods: A comprehensive literature search of PubMed, Embase, Cinahl, Web of Science, and the Cochrane Database was performed. The studies included randomized and non-randomized clinical trials, observational studies, and case series involving patients with distal femur fractures. Studies of other fracture patterns, studies conducted on children, pathological fractures, cadaveric studies, animal models, and those with non-clinical study designs were excluded. Results: 53 studies with 1788 patients were found to satisfy the inclusion and exclusion criteria. The most common harms were nonunion (14.8%), malunion (13%), fixation failure (5.3%), infection (3.7%), and symptomatic implant (3.1%). Time to full weight-bearing ranged from 5 to 24 weeks, averaging 12.3 weeks. The average duration of follow-up was 18.18 months, ranging from 0.5 to 108 months. Surgical time ranged between 40 and 540 min, with an average of 141 min. The length of stay in days was 12.7, ranging from 1 to 61. The average plate length was ten holes, ranging from 5 to 20 holes. Conclusion: This review aimed to systematically synthesize the available evidence on the risk associated with locked plating osteosynthesis in distal femur fractures. Nonunion is the most common harm and is the primary cause of reoperation. The overall combined risk of a major and critical complication (i.e., requiring reoperation) is approximately 20%.

Optimal blocking screw placement for retrograde IM nail fixation of distal femur fracture: a standardized biomechanical study of "osteoporotic" synthetic bone

PURPOSE

Intramedullary (IM) nail use for metaphyseal fracture management is problematic in long bones like the femur because the larger medullary cavity allows increased fracture motion and potentially increased implant failure and malunion/nonunion risk; Achieving effective distal femur fracture fixation is even more difficult in osteoporotic bone. Blocking screws to control IM nail movement are known to be effective for tibia fracture management. Few studies have evaluated IM nail and blocking screw use efficacy for distal femur fracture fixation in osteoporotic bone.

METHODS

This study used an osteoporosis simulation synthetic bone model to evaluate retrograde IM nail fixation of a standardized non-comminuted, extra-articular distal femur fracture with and without blocking screws. The hypothesis was that use of one or two blocking screws would increase IM nail fixation stability as evidenced by greater peak IM nail load and lesser movement. A servohydraulic device under displacement control collected loading force versus movement deflection data. Shapiro-Wilk tests confirmed data normality. One-way analysis of variance and Tukey post hoc tests were used to compare condition specific loading force and movement differences.

RESULT

In the coronal plane, blocking screw conditions displayed greater loading ranges (38.3 ± 2 vs. 19.1 ± 2 N, 100.5% difference) (p < 0.0001) and lesser movement (2.0 ± 0.3 vs. 6.86 ± 0.4 mm, 243% difference) (p < 0.0001). In the sagittal plane, the two blocking screw condition displayed a significantly greater loading magnitude (29.9 ± 6 vs. 20.8 ± 2.3 N, 43.8% difference) than the identical control condition without blocking screws (p = 0.018); however, movements were comparable (p = 0.82). Long-axis rotational loading failed to reveal load magnitude differences (p = 0.28); however, two different blocking screw conditions displayed decreased movement (1.32 ± 0.2 vs. 2.05 ± 0.3 mm, 53.8% difference) compared to other conditions (p ≤ 0.018).

CONCLUSIONS

Use of one or two blocking screws on the medial and lateral sides of the IM nail decreased coronal plane movement in the intramedullary canal. Combining retrograde IM nail implantation with blocking screws reduced medial-lateral IM nail movement and increased fracture stability. These characteristics may help prevent fixation failure, malunion, and even nonunion in patients with a distal femur fracture in osteoporotic bone.

Sensory substitution for orthopaedic gait rehabilitation: A systematic review and meta-analysis for clinical practice guideline development

Introduction

Sensory Substitution is a biofeedback intervention whereby at least sensory system is utilised to supplement environmental information which is traditionally gathered by another sense.

Objective

To present an evidence-based overview of the feasibility and effectiveness of wearable Sensory Substitution devices on gait outcomes in orthopaedic patient populations.

Methods

This Systematic Review and Meta-Analysis was reported according to the PRISMA 2020 statement. PubMed, the Cochrane Library, Web of science and PEDro were searched for relevant published literature. Inclusion criteria limited the search strictly to patients diagnosed with an orthopaedic condition and who were randomly grouped to a Sensory Substitution intervention or conventional therapy/training or an equivalent placebo intervention.

Results

Nine Randomised Controlled Trials and three Crossover Trials investigating the effectiveness of Sensory Substitution supplemented gait training were identified and included participants with a variety of orthopaedic conditions. Meta-Analyses revealed positive findings of feasibility as well as statistical and clinical effect of the interventions in improving measures of gait speed, weight-bearing control, measures of functionality and subjective self-reporting. Meta-Analyses also revealed the interventions effects were not significant in the management of pain and retention of gait speed. Negatively reinforced Sensory Substitution biofeedback was statistically and clinically effective, whilst positively reinforced biofeedback was not.

Conclusion

For orthopaedic patient populations to improve gait speed, weight-bearing control, functionality, pain and self-report measures, the authors recommend a Sensory Substitution supplemented gait training programme with negative biofeedback on performance. The intervention should be undertaken for 20 min per day, 3 days per week for 5 weeks. The intervention should coincide with structured analgesia administration to facilitate effective pain management. Limitations of the data included some low sample sizes and large age-ranges. No financial support was provided for this study.

Weight-bearing in Trauma Surgery (WiTS) Study: A national survey of UK Trauma & Orthopaedic multidisciplinary health professionals

INTRODUCTION

Weight-bearing (WB) status following a fracture or surgical fixation is an important determinant of the mechanical environment for healing. In order for healthcare professionals to communicate and understand the extent of bearing weight through a limb, clear terminology must be used. There is widespread variation in the usage and definitions of WB terminology in the literature and clinical practice. This study sought to define the understanding and extent of variation across the United Kingdom.

METHODS

A nationwide online survey of UK-based Trauma & Orthopaedic (T&O) multidisciplinary healthcare professionals was conducted. Participants answered seven questions assessing their usage and understanding of various WB terminology.

RESULTS

A total of 707 responses were received: 48% by doctors, 32% by physiotherapists, 13% by occupational therapists and 7% from other healthcare professionals. In terms of understanding of WB terminology with respect to percentage body weight (BW), 89% of respondents interpret 'full WB' as 100% BW, 97% interpret 'non WB' as 0% BW, 80% interpret 'partial WB' as 50% BW, and 89% interpret 'touch/toe-touch WB' as 10% or 20% BW. There were statistically significant differences between the responses of doctors and therapists for these four terms, with doctors tending to give higher %BW values. 'Protected WB' and 'WB as tolerated' had less consensus and more variability in responses. The majority (68%) of respondents do not usually quantify terminology such as 'partial WB' with a value, and 94% agreed that standardisation of WB terminology would improve communication amongst professionals.

CONCLUSION

This study provides evidence of the substantial variation in the understanding of WB terminology amongst healthcare professionals, which likely results in ambiguous rehabilitation advice. Existing literature has shown that patients struggle to comply with terms such as 'partial weight-bearing'. We recommend consensus within the T&O multidisciplinary community to standardise and define common weight-bearing terminology.

Biomechanical optimization of the far cortical locking technique for early healing of distal femur fractures

This finite element study optimized far cortical locking (FCL) technology for early callus formation in distal femur fracture fixation with a 9-hole plate using FCL screws proximal to, and standard locking screws distal to, the fracture. Analyses were done for 120 possible FCL screw configurations by varying FCL screw distribution and number. A hip joint force of 700 N (i.e. 100% x body weight) was used, which corresponds to a typical 140 N "toe-touch" foot-to-ground force (i.e. 20% x body weight) suggested to patients immediately after surgery. Increased FCL screw distribution (i.e. shorter plate working length) caused a decrease at the medial side and an increase at the lateral side of the axial interfragmentary motion (AIM), mildly affected shaft and condylar cortex Von Mises max stress (σ_MAX), increased plate σ_MAX, and decreased shaft FCL screw and condylar locking screw σ_MAX. Increased FCL screw number decreased AIM and σ_MAX on the shaft cortex, condylar cortex, plate, and FCL screws, but not condylar screws. The optimal FCL screw configuration had 3 FCL screws in plate holes #1, 5, and 6 (proximal to distal) for optimal AIM of 0.2 - 1 mm and reduce shear fracture motion, thereby encouraging early callus formation.

Biomechanical design using in-vitro finite element modeling of distal femur fracture plates made from semi-rigid materials versus traditional metals for post-operative toe-touch weight-bearing

This proof-of-concept study designs distal femur fracture plates from semi-rigid materials vs. traditional metals for toe-touch weight-bearing recommended to patients immediately after surgery. The two-fold goal was to (a) reduce stress shielding (SS) by increasing cortical bone stress thereby reducing the risk of bone absorption and plate loosening, and (b) reduce delayed healing (DH) via early callus formation by optimizing axial interfragmentary motion (AIM). Finite element analysis was used to design semi-rigid plates whose elastic moduli E ensured plates permitted AIM of 0.2 - 1 mm for early callus formation. A low hip joint force of 700 N (i.e. 100% x body weight) was applied, which corresponds to a typical 140 N toe-touch foot-to-ground force (i.e. 20% x body weight) recommended to patients after surgery. Analysis was done using 2 screw materials (steel or titanium) and types (locked or non-locked). Steel and titanium plates were also analyzed. Semi-rigid plates (vs. metal plates) had lower overall femur/plate construct stiffnesses of 508 - 1482 N/mm, higher cortical bone stresses under the plate by 2.02x - 3.27x thereby reducing SS, and lower E values of 414 - 2302 MPa to permit AIM of 0.2 - 1 mm thereby reducing DH.