Influence of biomechanical parameters on cranial cruciate ligament–deficient or –intact canine stifle joints assessed by use of a computer simulation model

Nathan P. Brown Department of Bioengineering, J. B. Speed School of Engineering, University of Louisville, Louisville, KY 40202.

Search for other papers by Nathan P. Brown in
Current site
Google Scholar
PubMed
Close
 PhD
,
Gina E. Bertocci Department of Bioengineering, J. B. Speed School of Engineering, University of Louisville, Louisville, KY 40202.

Search for other papers by Gina E. Bertocci in
Current site
Google Scholar
PubMed
Close
 PhD
, and
Denis J. Marcellin-Little Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607.

Search for other papers by Denis J. Marcellin-Little in
Current site
Google Scholar
PubMed
Close
 DEDV

Abstract

OBJECTIVE To investigate the influence of 4 biomechanical parameters on canine cranial cruciate ligament (CrCL)-intact and -deficient stifle joints.

SAMPLE Data for computer simulations of a healthy 5-year-old 33-kg neutered male Golden Retriever in a previously developed 3-D rigid body pelvic limb computer model simulating the stance phase during walking.

PROCEDURES Canine stifle joint biomechanics were assessed when biomechanical parameters (CrCL stiffness, CrCL prestrain, body weight, and stifle joint friction coefficient) were altered in the pelvic limb computer simulation model. Parameters were incrementally altered from baseline values to determine the influence on stifle joint outcome measures (ligament loads, relative tibial translation, and relative tibial rotation). Stifle joint outcome measures were compared between CrCL-intact and -deficient stifle joints for the range of parameters evaluated.

RESULTS In the CrCL-intact stifle joint, ligament loads were most sensitive to CrCL prestrain. In the CrCL-deficient stifle joint, ligament loads were most sensitive to body weight. Relative tibial translation was most sensitive to body weight, whereas relative tibial rotation was most sensitive to CrCL prestrain.

CONCLUSIONS AND CLINICAL RELEVANCE In this study, computer model sensitivity analyses predicted that CrCL prestrain and body weight influenced stifle joint biomechanics. Cranial cruciate ligament laxity may influence the likelihood of CrCL deficiency. Body weight could play an important role in management of dogs with a CrCL-deficient stifle joint.

Abstract

OBJECTIVE To investigate the influence of 4 biomechanical parameters on canine cranial cruciate ligament (CrCL)-intact and -deficient stifle joints.

SAMPLE Data for computer simulations of a healthy 5-year-old 33-kg neutered male Golden Retriever in a previously developed 3-D rigid body pelvic limb computer model simulating the stance phase during walking.

PROCEDURES Canine stifle joint biomechanics were assessed when biomechanical parameters (CrCL stiffness, CrCL prestrain, body weight, and stifle joint friction coefficient) were altered in the pelvic limb computer simulation model. Parameters were incrementally altered from baseline values to determine the influence on stifle joint outcome measures (ligament loads, relative tibial translation, and relative tibial rotation). Stifle joint outcome measures were compared between CrCL-intact and -deficient stifle joints for the range of parameters evaluated.

RESULTS In the CrCL-intact stifle joint, ligament loads were most sensitive to CrCL prestrain. In the CrCL-deficient stifle joint, ligament loads were most sensitive to body weight. Relative tibial translation was most sensitive to body weight, whereas relative tibial rotation was most sensitive to CrCL prestrain.

CONCLUSIONS AND CLINICAL RELEVANCE In this study, computer model sensitivity analyses predicted that CrCL prestrain and body weight influenced stifle joint biomechanics. Cranial cruciate ligament laxity may influence the likelihood of CrCL deficiency. Body weight could play an important role in management of dogs with a CrCL-deficient stifle joint.

Deficiency of the CrCL is the leading orthopedic condition diagnosed in canine stifle joints,1 with a prevalence of 2.55% across all breeds2 and an economic impact in the United States exceeding $1.3 billion in 2003.3 The CrCL stabilizes the stifle joint by limiting cranial tibial translation and internal tibial rotation relative to the femur.4 Rupture of the CrCL leads to stifle joint lameness, pain, dysfunction, and osteoarthritis.5 Management of CrCL deficiency in larger dogs typically requires stifle joint–stabilizing surgical intervention,6 but no surgical technique has been universally accepted.7 Deficiency of the CrCL often results from a degenerative process rather than from trauma, but the pathogenesis remains unclear and is likely multifactorial in origin.8 Risk factors for CrCL deficiency may include excessive body weight, stifle joint conformation, and integrity of the CrCL.8,9 As body weight increases, CrCL loading likely increases, which leads to ligament fatigue and failure.8 The causal relationship between synovitis, CrCL deficiency, and osteoarthritis is unclear, but evidence suggests that stifle joint degradation is holistically exacerbated by the presence of these conditions.10,11 Osteoarthritis can increase friction in the bovine stifle joint,12 but the role of stifle joint friction on CrCL deficiency is unknown. Finally, CrCL biomechanical properties such as stiffness and prestrain, an indicator of laxity in the CrCL, may influence the likelihood for CrCL deficiency, considering that increased joint laxity has been found to increase the risk for anterior cruciate ligament injury in humans.13 Furthermore, CrCL stiffness and prestrain may change before or during the onset of CrCL deficiency and influence the progression of CrCL degradation. The influence of these parameters on CrCL deficiency in dogs requires further investigation.

Computer models facilitate parametric analysis by isolating factors that influence model outcomes. Canine pelvic limb models have been used to investigate biomechanics of intact and CrCL-deficient stifle joints as well as biomechanics associated with variation in tibial plateau angle, femoral condyle diameter, patellar ligament insertion location, stifle joint ligament stiffness, and stifle joint ligament prestrain.14–16 The purpose of the study reported here was to investigate the influence of CrCL stiffness, CrCL prestrain, body weight, and SJFC on stifle joint ligament loads, tibial translation, and tibial rotation. Parametric analyses were conducted by means of a 3-D canine pelvic limb computer simulation model. We hypothesized that variation in biomechanical parameters would influence ligament loads, tibial translation, and tibial rotation in CrCL-intact and CrCL-deficient stifle joints.

Materials and Methods

Model design and simulation

Computer-aided design and modeling softwarea was used to develop a 3-D canine pelvic limb quasistatic computer model for the stance phase of a walking gait.14 The model was based on a 5-year-old 33-kg neutered male Golden Retriever with no known orthopedic or neurologic disease, as determined on the basis of medical records. The dog was walked on a leash in a straight line, and motion capture kinematic data were collected with 8 infrared cameras that tracked reflective markers placed on the skin over bony landmarks of the pelvis and left pelvic limb. Furthermore, GRFs and moments were collected for the left pelvic limb by use of a force platform placed level with the ground. Pelvic limb joint reactions were determined by inverse dynamics analysis with the measured GRFs and moments. Pelvic limb muscle forces were determined throughout the stance phase by means of the minimization of maximal muscle stress optimization strategy on the basis of stifle joint reaction moments determined from inverse dynamics analysis.14,16 Motion capture kinematics, GRFs, and optimized muscle forces for a representative walking trial were used to generate the baseline model.

Model simulation during the stance phase of the gait was conducted at 10% discrete intervals by use of rigid body motion softwareb for both CrCL-intact and -deficient stifle joints.14 Outcome measures were CrCL, CaCL, MCL, and LCL loads as well as tibial translation and tibial rotation. Ligament loads were normalized by use of baseline body weight. The RTT was defined as follows:

article image

where FT is the fixed-point tibial translation (ie, distance of the tibial tuberosity position relative to a fixed point on the femur along the craniocaudal axis), with the terms deficient and intact denoting CrCL status. The RTR was defined as follows:

article image

where R is the internal-external rotation, as defined in another study,17 with the terms deficient and intact denoting CrCL status.

Parametric analysis

Model parameters that were altered included CrCL stiffness, CrCL prestrain, body weight, and SJFC. These parameters were independently and incrementally altered from the baseline value to generate a unique scenario within the model. In the model, the entire stance phase of walking was simulated for each scenario. The CrCL stiffness was the product of ligament cross-sectional area and the tangent modulus reported for Rottweilers (198 MPa).14,18 Five CrCL stiffness scenarios were evaluated (–20%, −10%, 0% [baseline], 10%, and 20%) for the CrCL-intact stifle joint. Only the CrCL-intact model was simulated because the CrCL-deficient model did not contain a CrCL. The CrCL zero-strain free length was the minimum CrCL length during the stance phase for the baseline CrCL-intact model.14,19 The minimum in vivo canine CrCL strain during flexion-extension approached zero for stifle joint sagittal plane angles between 120° and 140°, which correspond to joint angles occurring during stance.19 Five CrCL prestrain scenarios were evaluated (–4%, −2%, 0% [baseline], 2%, and 4%) for the CrCL-intact stifle joint. Again, only the CrCL-intact model was simulated because the CrCL-deficient model did not contain a CrCL. Body weight influences GRFs, the vertical ground reaction moment, and muscle force magnitudes. Five body weight scenarios were evaluated for both CrCL-intact and -deficient stifle joints; GRFs and the vertical moment were varied by −20%, −10%, 0% (baseline), 10%, and 20%. Stifle joint reaction forces and moments determined through inverse dynamics analysis14 were calculated for each scenario by means of the altered GRF and moment magnitudes. Muscle force optimization by use of the minimization of maximal muscle stress strategy was repeated with the recalculated stifle joint reaction moments to establish unique muscle forces for each scenario.14 Menisci surface contours were adapted to the tibial plateau, and the tibiomeniscal structure interacted with the femoral condyles.12,14 Contact elements were included to prevent penetration between the femur and menisci, between the femur and tibia, and between the femur and patella by means of the following contact model:

article image

where Fn is the contact force, k is the stiffness, g is the contact penetration during simulation, e is the elastic component exponent, dg/dt is the instantaneous rate of change of g with respect to time, and f(g, cmax, dmax) is a contact penetration step function whereby cmax is the maximum damping and dmax is the penetration at which cmax occurs.14 Furthermore, each contact element pair had a static and dynamic friction coefficient of 0.001 in the baseline model, and each contact pair friction coefficient was simultaneously altered to represent changes in SJFC.12,14 Seven SJFC scenarios were evaluated (0.0001, 0.0005, 0.001 [baseline], 0.005, 0.01, 0.05, and 0.1) for both CrCL-intact and -deficient stifle joints.

Comparative analysis

Peak model outcome measures during the stance phase for each parameter were compared against values for the baseline CrCL-intact or -deficient stifle joint. Furthermore, the influence of each parameter was assessed on the basis of peak (absolute value) stance-phase sensitivity index (ie, percentage change in an outcome measure divided by the percentage change in an input parameter).14 For example, a 5% increase in an outcome measure caused by a 10% increase in an input parameter corresponded to a sensitivity index of 0.5. Therefore, higher sensitivity index values equated to greater sensitivity to that parameter.

Results

Parametric analysis

Eighteen unique scenarios that differed from the baseline scenario were simulated for each 10% discrete interval during the stance phase for the CrCL-intact stifle joint (162 total simulations, not including the baseline scenario simulations). Ten scenarios uniquely different from the baseline scenario were simulated for each discrete interval during the stance phase for the CrCL-deficient stifle joint (90 total simulations, not including the baseline scenario simulations). Peak ligament loads (Figure 1), peak RTT and RTR (Figure 2), and peak sensitivity indices (Table 1) across the stance phase were compared for the range of the various parameters to determine the parameter that had the greatest influence on model outcome measures. The range of minimum and maximum peak ligament loads (Figure 3) and RTT and RTR (Figure 4) across the scenarios were compared with values for the baseline scenario.

Figure 1—
Figure 1—

Computer-simulated peak loads for the CrCL (circles), CaCL (squares), LCL (triangles), and MCL (crosses) in CrCL-intact (A, B, C, and E) and -deficient (D and F) stifle joints, of a dog compared with baseline values (vertical dotted line), for changes in CrCL stiffness, CrCL prestrain, body weight (BW), and SJFC. Peak values are reported as a percentage of baseline BW (% BW). Graphs are not provided for CrCL stiffness and CrCL prestrain analyses in CrCL-deficient stifle joints because of the absence of the CrCL.

Citation: American Journal of Veterinary Research 76, 11; 10.2460/ajvr.76.11.952

Figure 2—
Figure 2—

Peak RTT (A–D) and RTR (E–H) for changes in CrCL stiffness (A and E), CrCL prestrain (B and F), BW (C and G), and SJFC (D and H), compared with baseline values (vertical dotted line). For CrCL stiffness and CrCL prestrain analyses, RTT and RTR are the difference between the baseline CrCL-deficient stifle joint and the altered CrCL-intact stifle joint. See Figure 1 for remainder of key.

Citation: American Journal of Veterinary Research 76, 11; 10.2460/ajvr.76.11.952

Figure 3—
Figure 3—

Range of change in peak loads for the CrCL (vertical-striped bars), CaCL (black bars), LCL (diagonal-striped bars), and MCL (horizontal-striped bars) compared with baseline values, of CrCL-intact (white background) and -deficient (stippled background) stifle joints for changes in CrCL stiffness (CrCL-intact stifle joint only), CrCL prestrain (CrCL-intact stifle joint only), BW, and SJFC.

Citation: American Journal of Veterinary Research 76, 11; 10.2460/ajvr.76.11.952

Figure 4—
Figure 4—

Range of change in peak RTT (A) and RTR (B) from baseline values for changes in CrCL stiffness, CrCL prestrain, BW, and SJFC. For CrCL stiffness and CrCL prestrain analyses, RTT and RTR were the difference between the baseline CrCL-deficient stifle joint and the altered CrCL-intact stifle joint.

Citation: American Journal of Veterinary Research 76, 11; 10.2460/ajvr.76.11.952

Table 1—

Computer-simulated sensitivity indices of peak outcome measures for changes in CrCL stiffness, CrCL prestrain, body weight, and SJFC in CrCL-intact and -deficient stifle joints of a dog.

 CrCL loadCaCL loadLCLloadMCL load  
ParameterIntactDeficientIntactDeficientIntactDeficientIntactDeficientRTTRTR
CrCL stiffness change (%)
–200.4NA0.500.300000.2
–100.4NA0.500.400000.2
100.4NA0.400.200000.1
200.4NA0.40–0.900000.1
CrCL prestrain change (%)
–413.2NA3.703.80–10.8*01.114.7*
–216.0NA7.4011.700.200.910.2
218.3NA21.6014.3*0–0.700.75.8
420.7*NA24.2*011.00–0.800.96.9
BW change (%)
–2000–1.04.5*–0.44.5*01.9*4.6*1.3
–100.10–1.50.1–0.40.20.2–0.50–0.9
1000–0.30.3–0.50.5–0.8–1.20–1.0
200.10–0.20.2–0.40.5–0.4–1.20–1.2
SJFC
0.00010000000000
0.000500000000.100
0.0050000000000
0.010000000000
0.050000000000
0.10000000000

Higher sensitivity index values indicate that a parameter has a greater influence on an outcome measure.

Peak (highest absolute value) sensitivity index for an outcome measure.

NA = Not applicable.

CrCL stiffness

The CrCL stiffness had little influence on ligament loads, tibial translation, and tibial rotation in CrCL-intact and -deficient stifle joints.

CrCL prestrain

Peak CrCL and CaCL loads increased 83% and 97%, respectively, from the baseline value for a CrCL prestrain of 4%. Peak baseline RTR was 4.6°, and peak RTR increased for a 4% increase in CrCL prestrain (5.9°) but decreased for a −4% CrCL prestrain (1.9°). The CrCL prestrain had the greatest influence on peak ligament loads, which led to the largest range of peak ligament loads in the CrCL-intact stifle joint. Furthermore, CrCL prestrain had the greatest influence on peak RTR, which led to the largest range of peak RTR values in the CrCL-deficient stifle joint. Therefore, ligament loads in the CrCL-intact stifle joint and RTR between the CrCL-intact and -deficient stifle joints were most sensitive to CrCL prestrain.

Body weight

Body weight had little influence on ligament loads in the CrCL-intact stifle joint. Peak CaCL load decreased 90%, compared with the baseline value, for a −20% change in body weight in the CrCL-deficient stifle joint. This reduction in peak CaCL load corresponded to a reduced RTT (1.8 mm, compared with the baseline value of 20.2 mm). Ligament loads in the CrCL-deficient stifle joint and RTT between the CrCL-intact and -deficient stifle joints were most sensitive to body weight.

SJFC

The SJFC had little influence on ligament loads in the CrCL-intact stifle joint. Peak CaCL load decreased 87%, compared with the baseline value, for an SJFC of 0.1 in the CrCL-deficient stifle joint. This reduction in peak CaCL load corresponded to a reduced RTT (1.7 mm, compared with a baseline value of 20.2 mm). Peak RTR increased from a baseline value of 4.6° to a value of 11.1° for an SJFC of 0.05.

Discussion

Computer models can be used to investigate joint biomechanics and complement in vivo and in vitro studies. Furthermore, computer models offer a critical biomechanical evaluation tool and are well suited for parametric analyses. With the multitude of potential parameters associated with CrCL deficiency and the absence of an identified primary cause for CrCL deficiency, a computer model simulating the canine pelvic limb during the stance phase of the gait provides a unique capability to directly compare effects of parameters. In the study reported here, stifle joint biomechanics were evaluated for both a CrCL-intact and -deficient stifle joint while independently altering 4 stifle joint biomechanical parameters (CrCL stiffness, CrCL prestrain, body weight, and SJFC). The influence of each parameter was assessed through model-predicted outcomes that included ligament loads, RTT, and RTR. The sensitivity index14 was used on the basis that it is an appropriate measure to assess outcome sensitivity across parameters because it normalizes the change in an outcome measure to the change in an input parameter.

Cranial cruciate ligament stiffness is dependent on CrCL cross-sectional area and the minimum CrCL elastic modulus, but the elastic modulus can differ among breeds.18 To our knowledge, the CrCL elastic modulus for Golden Retrievers is not known. Therefore, CrCL stiffness in our model was based on the elastic modulus determined for Rottweilers, which have a higher prevalence for CrCL deficiency than do Golden Retrievers.2 Therefore, the CrCL stiffness for this model may represent a dog with a high likelihood for CrCL deficiency. The CrCL stiffness may also differ in response to degradation or stress exposure prior to CrCL rupture. The influence of CrCL stiffness on model-predicted outcomes was assessed by altering CrCL stiffness through a range of ± 20% while all other ligament stiffness values were held constant. Ligament loads can increase with increasing stiffness in all ligaments (ie, CrCL, CaCL, LCL, and MCL),14 but in the present study, model-predicted outcomes had low sensitivity to change in CrCL stiffness alone.

Altering CrCL prestrain alone can represent potential changes in CrCL material properties as CrCL deficiency progresses. Baseline CrCL prestrain values used in the model for the present study were adapted from measured in vitro and in vivo canine stifle joint CrCL strains.19 Increased prestrain represented a CrCL that was tauter, whereas decreased prestrain represented a CrCL with laxity. As CrCL prestrain increased, cruciate ligament loads increased, but collateral ligament loads were less affected. In the CrCL-intact stifle joint, CrCL prestrain had the greatest influence on CrCL load, compared with results for scenarios in which other parameters were altered, and an increase in CrCL prestrain was the only scenario that led to both increased RTT and increased RTR. The stabilizing effect of the CrCL improved with increases in CrCL prestrain given that the CrCL carried a greater load and reduced cranial tibial translation and internal tibial rotation in the CrCL-intact stifle joint. Therefore, the mathematical difference between CrCL-intact and -deficient tibial translation and rotation (represented by RTT and RTR, respectively) increased with increasing CrCL prestrain in the CrCL-intact stifle joint. Although cruciate ligament loads increased with increases in CrCL prestrain, reduced joint laxity may stabilize the stifle joint and prevent CrCL injury. Increased joint laxity has been found to increase the likelihood of anterior cruciate ligament injury in humans.13 Sensitivity indices for CrCL prestrain were highest in the CrCL-intact stifle joint for all outcome measures as well as for the RTR between CrCL-intact and -deficient stifle joints. Sensitivity analysis indicated that CrCL prestrain had an appreciable effect on model outcomes but to a lesser extent than for changes in ligament prestrain in all ligaments (ie, CrCL, CaCL, LCL, and MCL).14

Ground reaction forces, which are proportional to body weight, influence joint moments.20 Muscles generate the forces necessary to produce joint moments required for a gait. Therefore, variation in body weight affects both GRFs and muscle forces, and simultaneous change in these parameters represented variation in dog body weight while maintaining constant geometry of the canine pelvic limb. Muscle force magnitudes and recruitment patterns in vivo are unknown; they were approximated from measured GRFs and by use of the minimization of maximal muscle stress optimization technique. The model in the present study predicted that body weight had little effect on ligament loads in the CrCL-intact stifle joint, possibly because the range of body weights evaluated may not have included morbid obesity. Reduction in body weight in obese dogs is considered a fundamental preventive measure to reduce joint loads and improve joint health.21 A retrospective study21 conducted to investigate signalment characteristics indicated that the likelihood of CrCL deficiency did not significantly increase for dogs that were normal weight, underweight, or overweight, but CrCL deficiency was 4 times as likely in dogs that were obese. In that study,21 normal weight, underweight, overweight, and obese were defined as ± 15% of ideal body weight, decrease > 15% of ideal body weight, increase 15% to 45% of ideal body weight, and increase > 45% of ideal body weight, respectively, compared with the ideal weight for dogs of the same breed and sex. These findings are consistent with the computer model-predicted findings reported here. Body weight was altered by ± 20% in the model, and within this range, we found that ligament loads were similar in the CrCL-intact stifle joint. In the CrCL-deficient stifle joint, ligament loads decreased for −20% body weight, which highlighted the benefits of reducing body weight when the CrCL has been compromised. Peak sensitivity indices for ligament load were highest for body weight in the CrCL-deficient stifle joint for all parameters evaluated. The RTR slightly decreased with increasing body weight, but change in peak RTR, compared with the baseline value, was less for body weight than for CrCL prestrain and SJFC.

Friction between articulating surfaces in synovial joints is often considered negligible,16,22 whereas in vitro friction coefficient measurements have been reported as < 0.03 in healthy bovine stifle joints12 and 0.09 in osteoarthritic joints.23 The SJFCs chosen in the model sensitivity analysis for the present study ranged from nearly frictionless to representative of osteoarthritic stifle joints. The model predicted that SJFC has little effect on stifle joint ligament loads in the CrCL-intact stifle joint. However, in the CrCL-deficient stifle joint, RTT was eliminated for 0.05 and 0.1 SJFC (which may represent osteoarthritis), and ligament loads were correspondingly reduced. During simulation with the baseline SJFC (0.001) in the CrCL-deficient stifle joint, the tibia subluxated, which increased RTT and prevented internal rotation as the tibia impinged on the femur. However, as SJFC increased to 0.05, tibial subluxation was prevented but internal rotation occurred. In comparison, the increased friction for 0.1 SJFC prevented internal rotation that occurred with 0.05 SJFC. However, stifle joint degradation attributable to or causing osteoarthritis may nullify beneficial effects resulting from increased friction representative of osteoarthritis. For instance, increased stifle joint friction may reduce range of motion and increase pain and lameness.

The findings from this computer-simulation study should be interpreted with consideration of the following limitations. The canine pelvic limb model represented results for 1 dog and was a digital approximation of a complex biomechanical system simulating the stance phase of a walking gait. Ground reaction forces and moments, inertial forces, muscle forces, ligament forces, and articular forces interdependently contribute to the walking gait. In the computer simulation model, muscle forces were determined throughout the stance phase by use of the minimization of maximal muscle stress optimization strategy that is based on calculation of stifle joint moments about the joint center from inverse dynamics analysis.14,24 These muscle forces were then used as inputs to the computer simulation model to determine ligament and articular contact forces necessary to balance muscle forces, inertial forces, and GRFs and moments, while maintaining limb segment kinematics, during model simulation. Additionally, the menisci were fixed to the tibia and not attached via meniscotibial ligaments that may have allowed slight movement relative to the tibia. Furthermore, the menisci were treated as rigid bodies that opposed femoral penetration, and the menisci contours were determined from CT images obtained at a stifle joint angle corresponding to midstance and were not changed across stance phase intervals. Although the range of motion of the stifle joint during the stance phase was relatively small (122° to 135°), changes in meniscal shape may occur with differing stifle joint angles and could potentially reduce or eliminate subluxation. Subsequent femorotibial impingement as well as femoromeniscal contact forces and model outcomes to evaluate the influence of SJFC could also be influenced by stifle joint angle. Resolution for the CT may have also led to menisci contours that were not completely smooth, which may have influenced femorotibial congruency. Finally, parameters were altered independently of each other. Combined parametric changes may be more representative of in vivo scenarios and may influence outcomes. However, despite these limitations, the canine pelvic limb model was used to evaluate changes in outcomes, compared with baseline values for CrCL-intact and -deficient models, for incremental changes in isolated stifle joint biomechanical parameters.

Sensitivity analyses confirmed that CrCL-intact and -deficient stifle joint biomechanics were affected by multiple parameters. Individual parameters were altered through clinically and physiologically relevant ranges. Therefore, model-predicted outcomes were assessed only for these chosen ranges and discrete values within these ranges. Patterns associated with changes outside these ranges may differ from outcomes obtained for the study reported here. Within the ranges of parameters evaluated, differences in model-predicted outcome sensitivity to these parameters suggested that CrCL prestrain in the CrCL-intact stifle joint and body weight in the CrCL-deficient stifle joint were more influential than were CrCL stiffness or SJFC. Therefore, CrCL laxity may increase the likelihood of CrCL deficiency, and management of CrCL deficiency may benefit from a decrease in body weight. These findings may be limited to dogs of similar morphological characteristics and may differ among breeds. Furthermore, the present study was conducted for a walking gait, which is a common, dynamic, and repeatable movement performed by dogs with and without CrCL deficiency. Findings may differ if stifle joint biomechanics are evaluated for other tasks such as trotting, running, sitting, turning, or jumping.

Acknowledgments

This manuscript represents a portion of a dissertation submitted by Dr. Brown to the University of Louisville Department of Mechanical Engineering as partial fulfillment of the requirements for a Doctor of Philosophy degree.

Supported by the American Kennel Club Canine Health Foundation (grant No. 01533-A awarded to Dr. Bertocci) and the University of Louisville Grosscurth Biomechanics Endowment.

The authors declare that there were no conflicts of interest.

The contents of this publication are solely the responsibility of the authors and do not necessarily represent the views of the American Kennel Club Canine Health Foundation.

ABBREVIATIONS

CaCL

Caudal cruciate ligament

CrCL

Cranial cruciate ligament

GRF

Ground reaction force

LCL

Lateral collateral ligament

MCL

Medial collateral ligament

RTR

Relative tibial rotation

RTT

Relative tibial translation

SJFC

Stifle joint friction coefficient

Footnotes

a.

SolidWorks, version 2010, SolidWorks Corp, Concord, Mass.

b.

SolidWorks Motion, version 2010, Structural Research and Analysis Corp, Santa Monica, Calif.

References

  • 1. Johnson JA, Austin C, Breur GJ. Incidence of canine appendicular musculoskeletal disorders in 16 veterinary teaching hospitals from 1980 through 1989. Vet Comp Orthop Traumatol 1994;7:5669.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 2. Witsberger TH, Villamil JA, Schultz LG, et al. Prevalence of and risk factors for hip dysplasia and cranial cruciate ligament deficiency in dogs. J Am Vet Med Assoc 2008;232:18181824.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3. Wilke VL, Robinson DA, Evans RB, et al. Estimate of the annual economic impact of treatment of cranial cruciate ligament injury in dogs in the United States. J Am Vet Med Assoc 2005;227:16041607.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4. Arnoczky SP, Marshall JL. The cruciate ligaments of the canine stifle: an anatomical and functional analysis. Am J Vet Res 1977;38:18071814.

    • Search Google Scholar
    • Export Citation
  • 5. Cook JL. Cranial cruciate ligament disease in dogs: biology versus biomechanics. Vet Surg 2010;39:270277.

  • 6. Vasseur PB. Clinical results following nonoperative management for rupture of the cranial cruciate ligament in dogs. Vet Surg 1984;13:243246.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7. Aragon CL, Budsberg SC. Applications of evidence-based medicine: cranial cruciate ligament injury repair in the dog. Vet Surg 2005;34:9398.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 8. Griffon DJ. A review of the pathogenesis of canine cranial cruciate ligament disease as a basis for future preventive strategies. Vet Surg 2010;39:399409.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9. Duval JM, Budsberg SC, Flo GL, et al. Breed, sex, and body weight as risk factors for rupture of the cranial cruciate ligament in young dogs. J Am Vet Med Assoc 1999;215:811814.

    • Search Google Scholar
    • Export Citation
  • 10. Bleedorn JA, Greuel EN, Manley PA, et al. Synovitis in dogs with stable stifle joints and incipient cranial cruciate ligament rupture: a cross-sectional study. Vet Surg 2011;40:531543.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11. Sutton S, Clutterbuck A, Harris P, et al. The contribution of the synovium, synovial derived inflammatory cytokines and neuropeptides to the pathogenesis of osteoarthritis. Vet J 2009;179:1024.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 12. McCann L, Ingham E, Jin Z, et al. Influence of the meniscus on friction and degradation of cartilage in the natural knee joint. Osteoarthritis Cartilage 2009;17:9951000.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 13. Smith HC, Vacek P, Johnson RJ, et al. Risk factors for anterior cruciate ligament injury: a review of the literature—part 1: neuromuscular and anatomic risk. Sports Health 2012;4:6978.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14. Brown NP, Bertocci GE, Marcellin-Little DJ. Development of a canine stifle computer model to evaluate cranial cruciate ligament deficiency. J Mech Med Biol 2013;13:1350043-11350043-29.

    • Search Google Scholar
    • Export Citation
  • 15. Brown NP, Bertocci GE, Marcellin-Little DJ. Evaluation of varying morphological parameters on the biomechanics of a cranial cruciate ligament-deficient or intact canine stifle joint with a computer simulation model. Am J Vet Res 2014;75:2633.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16. Shahar R, Banks-Sills L. A quasi-static three-dimensional, mathematical, three-body segment model of the canine knee. J Biomech 2004;37:18491859.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 17. Grood ES, Suntay WJ. A joint coordinate system for the clinical description of three-dimensional motions: application to the knee. J Biomech Eng 1983;105:136144.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18. Wingfield C, Amis AA, Stead AC, et al. Comparison of the biomechanical properties of Rottweiler and racing Greyhound cranial cruciate ligaments. J Small Anim Pract 2000;41:303307.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 19. Stone JE, Madsen NH, Milton JL, et al. Developments in the design and use of liquid-metal strain gages. Exp Mech 1983;23:129139.

  • 20. Browning RC, Kram R. Effects of obesity on the biomechanics of walking at different speeds. Med Sci Sports Exerc 2007;39:16321641.

  • 21. Adams P, Bolus R, Middleton S, et al. Influence of signalment on developing cranial cruciate rupture in dogs in the UK. J Small Anim Pract 2011;52:347352.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 22. Blankevoort L, Kuiper JH, Huiskes R, et al. Articular contact in a three-dimensional model of the knee. J Biomech 1991;24:10191031.

  • 23. Fung YC. Bone and cartilage. In: Biomechanics: mechanical properties of living tissues. 2nd ed. New York: Springer, 1993;531.

  • 24. Dumas R, Aissaoui R, de Guise JA. A 3D generic inverse dynamic method using wrench notation and quaternion algebra. Comput Methods Biomech Biomed Engin 2004;7:159166.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Figure 1—

    Computer-simulated peak loads for the CrCL (circles), CaCL (squares), LCL (triangles), and MCL (crosses) in CrCL-intact (A, B, C, and E) and -deficient (D and F) stifle joints, of a dog compared with baseline values (vertical dotted line), for changes in CrCL stiffness, CrCL prestrain, body weight (BW), and SJFC. Peak values are reported as a percentage of baseline BW (% BW). Graphs are not provided for CrCL stiffness and CrCL prestrain analyses in CrCL-deficient stifle joints because of the absence of the CrCL.

  • Figure 2—

    Peak RTT (A–D) and RTR (E–H) for changes in CrCL stiffness (A and E), CrCL prestrain (B and F), BW (C and G), and SJFC (D and H), compared with baseline values (vertical dotted line). For CrCL stiffness and CrCL prestrain analyses, RTT and RTR are the difference between the baseline CrCL-deficient stifle joint and the altered CrCL-intact stifle joint. See Figure 1 for remainder of key.

  • Figure 3—

    Range of change in peak loads for the CrCL (vertical-striped bars), CaCL (black bars), LCL (diagonal-striped bars), and MCL (horizontal-striped bars) compared with baseline values, of CrCL-intact (white background) and -deficient (stippled background) stifle joints for changes in CrCL stiffness (CrCL-intact stifle joint only), CrCL prestrain (CrCL-intact stifle joint only), BW, and SJFC.

  • Figure 4—

    Range of change in peak RTT (A) and RTR (B) from baseline values for changes in CrCL stiffness, CrCL prestrain, BW, and SJFC. For CrCL stiffness and CrCL prestrain analyses, RTT and RTR were the difference between the baseline CrCL-deficient stifle joint and the altered CrCL-intact stifle joint.

  • 1. Johnson JA, Austin C, Breur GJ. Incidence of canine appendicular musculoskeletal disorders in 16 veterinary teaching hospitals from 1980 through 1989. Vet Comp Orthop Traumatol 1994;7:5669.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 2. Witsberger TH, Villamil JA, Schultz LG, et al. Prevalence of and risk factors for hip dysplasia and cranial cruciate ligament deficiency in dogs. J Am Vet Med Assoc 2008;232:18181824.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3. Wilke VL, Robinson DA, Evans RB, et al. Estimate of the annual economic impact of treatment of cranial cruciate ligament injury in dogs in the United States. J Am Vet Med Assoc 2005;227:16041607.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4. Arnoczky SP, Marshall JL. The cruciate ligaments of the canine stifle: an anatomical and functional analysis. Am J Vet Res 1977;38:18071814.

    • Search Google Scholar
    • Export Citation
  • 5. Cook JL. Cranial cruciate ligament disease in dogs: biology versus biomechanics. Vet Surg 2010;39:270277.

  • 6. Vasseur PB. Clinical results following nonoperative management for rupture of the cranial cruciate ligament in dogs. Vet Surg 1984;13:243246.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7. Aragon CL, Budsberg SC. Applications of evidence-based medicine: cranial cruciate ligament injury repair in the dog. Vet Surg 2005;34:9398.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 8. Griffon DJ. A review of the pathogenesis of canine cranial cruciate ligament disease as a basis for future preventive strategies. Vet Surg 2010;39:399409.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9. Duval JM, Budsberg SC, Flo GL, et al. Breed, sex, and body weight as risk factors for rupture of the cranial cruciate ligament in young dogs. J Am Vet Med Assoc 1999;215:811814.

    • Search Google Scholar
    • Export Citation
  • 10. Bleedorn JA, Greuel EN, Manley PA, et al. Synovitis in dogs with stable stifle joints and incipient cranial cruciate ligament rupture: a cross-sectional study. Vet Surg 2011;40:531543.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11. Sutton S, Clutterbuck A, Harris P, et al. The contribution of the synovium, synovial derived inflammatory cytokines and neuropeptides to the pathogenesis of osteoarthritis. Vet J 2009;179:1024.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 12. McCann L, Ingham E, Jin Z, et al. Influence of the meniscus on friction and degradation of cartilage in the natural knee joint. Osteoarthritis Cartilage 2009;17:9951000.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 13. Smith HC, Vacek P, Johnson RJ, et al. Risk factors for anterior cruciate ligament injury: a review of the literature—part 1: neuromuscular and anatomic risk. Sports Health 2012;4:6978.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14. Brown NP, Bertocci GE, Marcellin-Little DJ. Development of a canine stifle computer model to evaluate cranial cruciate ligament deficiency. J Mech Med Biol 2013;13:1350043-11350043-29.

    • Search Google Scholar
    • Export Citation
  • 15. Brown NP, Bertocci GE, Marcellin-Little DJ. Evaluation of varying morphological parameters on the biomechanics of a cranial cruciate ligament-deficient or intact canine stifle joint with a computer simulation model. Am J Vet Res 2014;75:2633.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16. Shahar R, Banks-Sills L. A quasi-static three-dimensional, mathematical, three-body segment model of the canine knee. J Biomech 2004;37:18491859.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 17. Grood ES, Suntay WJ. A joint coordinate system for the clinical description of three-dimensional motions: application to the knee. J Biomech Eng 1983;105:136144.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18. Wingfield C, Amis AA, Stead AC, et al. Comparison of the biomechanical properties of Rottweiler and racing Greyhound cranial cruciate ligaments. J Small Anim Pract 2000;41:303307.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 19. Stone JE, Madsen NH, Milton JL, et al. Developments in the design and use of liquid-metal strain gages. Exp Mech 1983;23:129139.

  • 20. Browning RC, Kram R. Effects of obesity on the biomechanics of walking at different speeds. Med Sci Sports Exerc 2007;39:16321641.

  • 21. Adams P, Bolus R, Middleton S, et al. Influence of signalment on developing cranial cruciate rupture in dogs in the UK. J Small Anim Pract 2011;52:347352.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 22. Blankevoort L, Kuiper JH, Huiskes R, et al. Articular contact in a three-dimensional model of the knee. J Biomech 1991;24:10191031.

  • 23. Fung YC. Bone and cartilage. In: Biomechanics: mechanical properties of living tissues. 2nd ed. New York: Springer, 1993;531.

  • 24. Dumas R, Aissaoui R, de Guise JA. A 3D generic inverse dynamic method using wrench notation and quaternion algebra. Comput Methods Biomech Biomed Engin 2004;7:159166.

    • Crossref
    • Search Google Scholar
    • Export Citation

Advertisement