Knee joint reaction force during tibial diaphyseal lengthening: a study on a rabbit model

Contribution of Soft Tissue Passive Forces in Thumb Carpometacarpal Joint Distraction

Thumb carpometacarpal joint space changes when the surrounding soft tissues including the capsule, ligaments, and tendons are stretched or pulled away. When at rest, joint forces originate from passive contraction of muscles and the involvement of joint capsule and ligaments. Previous biomechanical models of hand and finger joints have mostly focused on the assessment of joint properties when muscles were active. This study aims to present an experimental-numerical biomechanical model of thumb carpometacarpal joint to explore the contribution of tendons, ligaments, and other soft tissues in the passive forces during distraction. Five fresh cadaveric specimens were tested using a distractor device to measure the applied forces upon gradual distraction of the intact joint. The subsequent step involved inserting a minuscule sensor into the joint capsule through a small incision, while preserving the integrity of tendons and ligaments, in order to accurately measure the fundamental intra-articular forces. A numerical model was also used to calculate the passive forces of tendons and ligaments. Before the separation of bones, the forces exerted by tendons and ligaments were relatively small compared to the capsule force, which accounted for approximately 92% of the total applied force. Contribution of tendons and ligaments, however, increased by further distraction. The passive force contribution by tendons at 2-mm distraction was determined less than 11%, whereas it reached up to 74% for the ligaments. The present study demonstrated that the ligament-capsule complex plays significant contribution in passive forces of thumb carpometacarpal joint during distraction.

Ulnohumeral joint static cartilage compression is affected by radial head implant size

INTRODUCTION

Radiocapitellar joint arthroplasty is a commonly performed procedure, which often leads to early failure or instability. Few studies assess the effect of radiocapitellar joint arthroplasty on the ulnohumeral joint. We hypothesized that static forces of contact (compressing cartilage, or cartilage relaxation contact force) would reveal the effect of varying radial head implant size and elbow position on the ulnohumeral joint.

METHODS

A minimally-invasive method of measuring cartilage relaxation contact force was utilized in 10 fresh-frozen human cadaveric specimens that did not require significant dissection or intraarticular sensor placement. Specimens were rigidly fixed in various positions of elbow flexion and forearm pronosupination with increasing radial head implant lengths. Uniaxial distracting forces were applied and displacement was repeatedly measured with resultant best-fit polynomial curves to determine inflections corresponding to the force required to overcome static cartilage relaxation as in previous work.

FINDINGS

Baseline mean (intra-cadaver) cartilage relaxation contact force was 11.8 N (standard error of the mean = 0.3) at 90° of elbow flexion and neutral rotation. There was little variation within specimens (Intraclass correlation coefficient > 0.94). Cartilage relaxation contact force increased at the ulnohumeral joint with radial head implant overstuffing (> 4 mm, P < 0.05) and elbow flexion (120°, P < 0.001). Pronosupination altered cartilage relaxation contact force in an implant-length independent manner (P < 0.05).

INTERPRETATION

Radiocapitellar joint arthroplasty implant length and elbow joint position independently contribute to increased cartilage relaxation contact force at the ulnohumeral joint. This further supports attempts at anatomic reconstruction of the radiocapitellar joint to prevent pathologic ulnohumeral joint loading.

Alterations in tibiotalar joint reaction force following syndesmotic injury are restored with static syndesmotic fixation

INTRODUCTION

Syndesmotic injury alters joint mechanics, which may fail to be restored unless an anatomic reduction is obtained.

METHODS

A minimally invasive method of measuring joint forces was utilized that does not require significant dissection or intraarticular placement of sensory instruments. Steinmann pins were placed in the tibia and talus of eight fresh-frozen human cadaveric lower extremities and a baseline joint reaction force was determined. A syndesmotic injury was created and reduction (anatomic and anterior malreduction) performed with one or two quadricortical screws and joint reaction forces were measured after the injury and subsequent repairs.

FINDINGS

Baseline mean tibiotalar joint reaction force was 31.4 (SD 7.3 N) and syndesmotic injury resulted in a 35% decrease (mean 20.3, SD 8.4 N, p < 0.01). Fixation of the injury using one or two syndesmotic screws resulted in significant increase compared to the injury state (mean 28.7, SD3.9 N, and mean 28.3, SD 6.4 N, p < 0.05), however there was no significant difference between the two methods of fixation. Malreduction of the fibula also increased joint reaction force compared to the injury state (mean 31.5, SD 5.2 N, p < 0.01), however a significant difference was not detected between malreduction and anatomic reduction.

INTERPRETATION

The present study demonstrates that syndesmotic injury decreases joint reaction force within the tibiotalar joint, suggesting ankle joint instability. Tibiotalar force was restored with anatomic reduction with either a 1 or 2 quadricortical syndesmotic screws. Furthermore, anterior malreduction restored joint reaction force to levels similar to those observed at baseline and with anatomic reduction.

LEVEL OF EVIDENCE

Level V: biomechanical/cadaver study.

Bone Formation and Adaptive Morphology of the Anterior Tibial Muscle in 3-mm Daily Lengthening Using High-Fractional Automated Distraction and Osteosynthesis with the Ilizarov Apparatus Combined with Intramedullary Hydroxyapatite-Coated Wire

Purpose

We studied osteogenesis and morphofunctional features of the anterior tibial muscle using 3-mm high-frequency automated lengthening with the Ilizarov apparatus alone and in combination with intramedullary nailing.

Material and Methods

Tibia was lengthened with a round-the-clock automated distractor at a 3-mm daily rate for 10 days in 16 mongrel dogs. In group 1 (n = 8), a 1.8-mm intramedullary titanium wire coated with hydroxyapatite was introduced into the tibial canal followed by Ilizarov frame mounting and transverse osteotomy of the diaphysis. Distraction mode was 0.025 mm x 120 increments a day. In group 2 (n = 8), distraction mode was the same but nailing was not used. Bone formation and the anterior tibial muscle were studied at two time points: (1) upon distraction completion; (2) three months after the apparatus removal. Bone formation was studied radiographically. Muscle preparations were examined histologically and stereomicroscopically.

Results

There was a threefold reduction in the distraction time in both groups. Consolidation took 13.83±4.02 days in group 1 and 33.7±2.4 days in group 2. Muscle macropreparations of the experimental limb in group 1 at study time points did not show significant differences from intact tissues. Muscle histostructure in both groups was characterized by activation of angiogenesis and myohistogenesis, but the volumetric density of microvessels in the lengthening phase was three times higher in group 1.

Conclusion

Combined technology significantly reduces the total lengthening procedure and does not compromise limb functions. Intramedullary HA-coated wires promote faster bone formation. The muscle was able to exhibit structural adaptation and plasticity of a restitution type.

Spring ligament tear decreases static stability of the ankle joint

BACKGROUND

Spring ligament tear is often found in advanced adult acquired flatfoot deformity and its reconstruction in conjunction with the deltoid ligament has been proposed to restore the tibiotalar and talonavicular joint stability. The aim of the present study is to determine the effect of spring ligament injury and subsequent reconstruction on static joint reactive force using a non-invasive method of measurement.

METHODS

Ten fresh-frozen human cadaveric lower legs were disarticulated at the knee joint. Static joint reactive force of the tibiotalar and talonavicular joint were measured at baseline, after spring ligament injury, and after ligament reconstruction. Reconstruction consisted of a forked semitendinosis allograft with dual limbs to reconstruct the tibionavicular and tibiocalcaneal ligaments.

FINDINGS

The mean baseline joint reactive force of the tibiotalar and talonavicular joints were 37.2 N + 8.1 N and 13.4 N + 4.2 N, respectively. The spring ligament injury model resulted in a significant 29% decrease in tibiotalar joint reactive force. Reconstruction of the tibionavicular limb resulted in a significant increase in tibiotalar and talonavicular joint reactive force compared to those seen in the injury state. Furthermore, the addition of the tibiocalcaneal limb significantly increased tibiotalar joint reactive force compared to those results obtained from the injury state and the tibionavicular limb alone.

INTERPRETATION

This is the first study to demonstrate diminished tibiotalar static joint reactive force in a spring ligament injury model with subsequent joint reactive force restoration using two-limbed reconstruction of the deltoid and spring ligament.

LEVEL OF EVIDENCE

Biomechanical Study.

Techniques of Force and Pressure Measurement in the Small Joints of the Wrist

BACKGROUND

The alteration of forces across joints can result in instability and subsequent disability. Previous methods of force measurements such as pressure-sensitive films, load cells, and pressure-sensing transducers have been utilized to estimate biomechanical forces across joints and more recent studies have utilized a nondestructive method that allows for assessment of joint forces under ligamentous restraints.

METHODS

A comprehensive review of the literature was performed to explore the numerous biomechanical methods utilized to estimate intra-articular forces.

RESULTS

Methods of biomechanical force measurements in joints are reviewed.

CONCLUSIONS

Methods such as pressure-sensitive films, load cells, and pressure-sensing transducers require significant intra-articular disruption and thus may result in inaccurate measurements, especially in small joints such as those within the wrist and hand. Non-destructive methods of joint force measurements either utilizing distraction-based joint reaction force methods or finite element analysis may offer a more accurate assessment; however, given their recent inception, further studies are needed to improve and validate their use.

Distal Radioulnar Joint Reaction Force Following Ulnar Shortening: Diaphyseal Osteotomy Versus Wafer Resection

PURPOSE

To compare how ulnar diaphyseal shortening and wafer resection affect distal radioulnar joint (DRUJ) joint reaction force (JRF) using a nondestructive method of measurement. Our hypothesis was that ulnar shortening osteotomy would increase DRUJ JRF more than wafer resection.

METHODS

Eight fresh-frozen human cadaveric upper limbs were obtained. Under fluoroscopic guidance, a threaded pin was inserted into the lateral radius orthogonal to the DRUJ and a second pin was placed in the medial ulna coaxial to the radial pin. Each limb was mounted onto a mechanical tensile testing machine and a distracting force was applied across the DRUJ while force and displacement were simultaneously measured. Data sets were entered into a computer and a polynomial was generated and solved to determine the JRF. This process was repeated after ulnar diaphyseal osteotomy, ulnar re-lengthening, and ulnar wafer resection. The JRF was compared among the 4 conditions.

RESULTS

Average baseline DRUJ JRF for the 8 arms increased significantly after diaphyseal ulnar shortening osteotomy (7.2 vs 10.3 N). Average JRF after re-lengthening the ulna and wafer resection was 6.9 and 6.7 N, respectively. There were no differences in JRF among baseline, re-lengthened, and wafer resection conditions.

CONCLUSIONS

Distal radioulnar joint JRF increased significantly after ulnar diaphyseal shortening osteotomy and did not increase after ulnar wafer resection.

CLINICAL RELEVANCE

Diaphyseal ulnar shortening osteotomy increases DRUJ JRF, which may lead to DRUJ arthrosis.

A nondestructive, reproducible method of measuring joint reaction force at the distal radioulnar joint

PURPOSE

To develop a nondestructive method of measuring distal radioulnar joint (DRUJ) joint reaction force (JRF) that preserves all periarticular soft tissues and more accurately reflects in vivo conditions.

METHODS

Eight fresh-frozen human cadaveric limbs were obtained. A threaded Steinmann pin was placed in the middle of the lateral side of the distal radius transverse to the DRUJ. A second pin was placed into the middle of the medial side of the distal ulna colinear to the distal radial pin. Specimens were mounted onto a tensile testing machine using a custom fixture. A uniaxial distracting force was applied across the DRUJ while force and displacement were simultaneously measured. Force-displacement curves were generated and a best-fit polynomial was solved to determine JRF.

RESULTS

All force-displacement curves demonstrated an initial high slope where relatively large forces were required to distract the joint. This ended with an inflection point followed by a linear area with a low slope, where small increases in force generated larger amounts of distraction. Each sample was measured 3 times and there was high reproducibility between repeated measurements. The average baseline DRUJ JRF was 7.5 N (n = 8).

CONCLUSIONS

This study describes a reproducible method of measuring DRUJ reaction forces that preserves all periarticular stabilizing structures. This technique of JRF measurement may also be suited for applications in the small joints of the wrist and hand.

CLINICAL RELEVANCE

Changes in JRF can alter native joint mechanics and lead to pathology. Reliable methods of measuring these forces are important for determining how pathology and surgical interventions affect joint biomechanics.

The Experimental Study on Promoting the Ilizarov Distraction Osteogenesis by the Injection of Liquid Alg/nHAC Biocomposites

Limb lengthening is frequently utilized in treating limb length inequalities, angulation deformities, nonunions, complex fractures, and deficiencies after tumor resection in more recent year. The procedure of limb lengthening pioneered by Ilizarov is now a widely accepted method for correcting limb length inequality and short stature as well as for bridging large defects in long bones. In order to promote bone healing during distraction osteogenesis and reduce the complications caused by limb lengthening pioneered, an alginate/nanohydroxyapatite/collagen (Alg/nHAC) composite was fabricated. General observation, histologically morphological observations, X-ray examination, biomechanical test, bone density, and the percentage area of bone trabecula were used to assay the ability of Alg/nHAC composite to promote bone healing. The present study demonstrates that the injection of liquid Alg/nHAC composites can significantly promote distraction osteogenesis. Alg/nHAC composite is promising for clinical application, solving the healing problem of backbone osteotomy and the fixing problem of metaphyseal backbone.

Biomechanical influence of pin placement and elbow angle on joint distraction and hinge alignment for an arthrodiatasis elbow-pin-fixator construct

Stiffness and contracture of the periarticular tissues are common complications of a post-traumatic elbow. Arthrodiatasis is a surgical technique that uses an external fixator for initial immobilization and subsequent distraction. The two prerequisites for an ideal arthrodiatasis are concentric distraction (avoiding bony contact) and hinge alignment (reducing internal stress). This study used the finite element (FE) method to clarify the relationship between these two prerequisites and the initial conditions (pin placement, elbow angle, and distraction mode). A total of 12 variations of the initial conditions were symmetrically arranged to evaluate their biomechanical influence on concentric distraction and hinge alignment. The humeroulnar surface was hypothesized to be ideally distracted orthogonal to the line joining the tips of the olecranon and the coronoid. The eccentric separation of the humeroulnar surfaces is a response to the non-orthogonality of the distracting force and joining line. Pin placement significantly affects the effective moment arm of the fixing pins to distract the bridged elbow. Both elbow angle and distraction mode directly alter the direction of the distracting force at the elbow center. In general, the hinges misalignment occurs in a direction opposite to the distraction-activated site. After joint distraction, the elastic deflection of the fixing pins inevitably makes both elbow and fixator hinges to misalign. This indicates that both joint distraction and hinge alignment are the interactive mechanisms. The humeroulnar separation is more concentric in the situation of the 120 degrees humeral distraction by using stiffer pins with convergent placement. Even so, the eccentric displacement of the elbow hinge is a crucial consideration in the initial placement of the guiding pin to compensate for hinge misalignment.

The effect of tibial lengthening on immature articular cartilage of the ankle joint

Is the articular cartilage of the immature ankle joint damaged by tibial lengthening? Sixteen immature rabbits underwent a 30% diaphyseal lengthening by tibial callotasis. Damage was assessed by scanning electronic microscopy and histomorphometry at the completion of distraction and after an additional 5 weeks. Despite joint contracture, little damage in the articular cartilage was observed in contrast to the knee joint. The findings show that the immature ankle joint is more resilient to stress than the knee and implies that reduced weight bearing and decreased joint movement alone are not sufficient to cause cartilage damage, at least in the ankle.

The role of variable muscle adaptation to limb lengthening in the development of joint contractures: an experimental study in the goat

Muscle stiffness and joint contractures are currently regarded as the most common complications of limb lengthening. To better understand the mechanisms of joint contractures, architectural changes of all involved muscles were analyzed in 9 goats after 20% tibial lengthening with standard distraction protocol.All 13 muscles of the goat's tibia were found to be organized into an anterior compartment with 2 longitudinal and 4 pennate muscles and a posterior compartment with 1 longitudinal and 6 pennate muscles. Longitudinal muscles showed better compliance to distraction than pinnate muscles. Although muscle-to-bone lengthening ratio ranged widely (0-1.2), most of the muscles and especially those located in the posterior compartment showed much less lengthening than the bone. Muscular portions of the muscles lengthened more substantially (average, 17%) than their associated tendons (average, 7%). Muscle fiber length changes varied greatly between muscles (range, 0%-88%). Normalization of muscle fiber length revealed considerable elongation of anterior muscles fibers (25%) that was associated with an addition of new sarcomeres in series. Fiber length increase of all posterior muscles but one occurred by stretching of existing sarcomeres, with little addition or even dissolution of sarcomeres in series. This correlated with muscle mass changes showing significant muscle atrophy in the posterior compartment and better mass preservation in the anterior compartment.The study revealed striking difference in response to limb lengthening between individual muscles and muscles from antagonistic compartments in particular. Poor sarcomerogenesis in the posterior muscles leading to their insufficient length increase seems to play major role in the development of joint contractures.

Biomechanics of the rabbit knee and ankle: Muscle, ligament, and joint contact force predictions

Mathematical models of small animals that predict in vivo forces acting on the lower extremities are critical for studies of musculoskeletal biomechanics and diseases. Rabbits are advantageous in this regard because they remodel their cortical bone similar to humans. Here, we enhance a recent mathematical model of the rabbit knee joint to include the loading behavior of individual muscles, ligaments, and joint contact at the knee and ankle during the stance phase of hopping. Geometric data from the hindlimbs of three adult New Zealand white rabbits, combined with previously reported intersegmental forces and moments, were used as inputs to the model. Muscle, ligament, and joint contact forces were computed using optimization techniques assuming that muscle endurance is maximized and ligament strain energy resists tibial shear force along an inclined plateau. Peak forces developed by the quadriceps and gastrocnemius muscle groups and by compressive knee contact were within the range of theoretical and in vivo predictions. Although a minimal force was carried by the anterior cruciate and medial collateral ligaments, force patterns in the posterior cruciate ligament were consistent with in vivo tibial displacement patterns during hopping in rabbits. Overall, our predictions compare favorably with theoretical estimates and in vivo measurements in rabbits, and enhance previous models by providing individual muscle, ligament, and joint contact information to predict in vivo forces acting on the lower extremities in rabbits.

The effect of tibial lengthening on immature articular cartilage of the knee joint

OBJECTIVE

To investigate the acute response of immature articular cartilage, in the distraction and consolidation phases, to 30% tibial lengthening.

DESIGN

Sixteen immature New Zealand white rabbits underwent diaphyseal lengthening of the left tibia by callotasis at a distraction rate of 0.4mm twice daily. A sham control group of 12 rabbits underwent fixation and osteotomy without lengthening. In each group, half of the rabbits were killed at the end of the distraction phase or at an equivalent time period and the rest were killed after an additional 5 weeks (consolidation phase). The tibial condyles and synovial fluid in the knee joint cavity were taken for laboratory examination. Sulfated glycosaminoglycan in synovial fluid was estimated using a colorimetric method. Sections along the mid-coronal plane of the whole of the tibial condyles were examined histologically and by scanning electron microscopy. A grading system was used to make a semiquantitative assessment of the histopathological changes in articular cartilage.

RESULTS

Damage to the immature articular cartilage had occurred by the end of the distraction period and the cartilage continued to deteriorate in the consolidation phase of 5 weeks. However, when compared with a similar study in a mature rabbit model, damage to immature cartilage appeared less severe.

CONCLUSION

This model of 30% lengthening caused acute cartilage damage which did not recover in the short term. The result may have implications for longer lengthening in children; the effects may be disadvantageous and lead to degenerative diseases later in life.