To study the association between hip and ankle biomechanics during gait and moderate knee osteoarthritis (OA).

Gait analysis was performed on a group of forty-four patients clinically diagnosed with moderate knee OA, and on a group of sixty asymptomatic subjects. Three-dimensional net joint angles and net joint reaction moments at the hip, knee and ankle joints were calculated. Peak values were extracted from the gait waveform patterns and compared between the two subject groups with Student’s t-tests.

The peak hip extension moment, the peak hip adduction moment, the peak hip internal and external rotation moments, and the peak ankle dorsiflexion and plantarflexion moments were all reduced in the knee osteoarthritis population compared to the asymptomatic population.

Differences in knee joint loading patterns with moderate knee osteoarthritis have been previously reported, but these data suggest that changes in the mechanical environment of all lower extremity joints are associated with early stages of knee osteoarthritis. Other studies have associated reduced peak hip adduction moments with reduced likelihood of OA progression. These data provide a rationale for hip abductor muscle strengthening as a means to lower knee joint loading.

The pathogenesis of knee osteoarthritis is complex and involves many correlated factors that can be measured with gait analysis. Important biomechanical factors may lie in the interrelationships between variables. This study demonstrated the use of a multidimensional gait data analysis technique that simultaneously considered multiple time varying and constant measures. The gait patterns of normal and knee osteoarthritic subjects were successfully separated with a misclassification error rate of < 6%. One of the most discriminatory features identified an important knee osteoarthritis difference during the loading response phase of the gait cycle.

The objective of this study was to detect biomechanical factors of knee osteoarthritis with a multidimensional gait data analysis technique.

A multidimensional gait data analysis technique detected a very discriminatory feature that described a knee osteoarthritis difference during the loading response phase of the gait cycle.

The combination of variables involved in the loading response feature may be important to the onset and development of knee osteoarthritis.

Discriminatory gait features associated with knee osteoarthritis were identified with a misclassification error rate of < 6%. In a very discriminatory feature, the loading response phase of the gait cycle was completely isolated as important. Body mass index (BMI) was the greatest contributing factor to the loading response feature.

Three-dimensional gait analysis was performed on fifty elderly patients with severe knee osteoarthritis and sixty-three elderly asymptomatic subjects. Three components of knee joint angles, moments and forces were calculated. Body mass index (BMI), radiographic measures and stride characteristics were also measured. A multivariate statistical technique extracted important features from the data and a discrimination procedure defined the optimal separation between the two groups.

The importance of loading response had been hypothesized previously, and this study quantitatively identified a very discriminatory gait pattern difference during loading response. The difference described was multidimensional. Although BMI was the largest contributing factor, there was no univariate difference in BMI between the two groups.

Funding: NSERC

The purpose of our study was to compare the performance of a new intramedullary reaming device to a contemporary reaming system. The new intramedullary reaming device was the Synthes Reamer/Irrigator/Aspirator reamer (RIA) which differs from contemporary reaming devices in that it has a built-in irrigation and aspiration system to reduce the intramedullary pressures and temperatures associated with reaming. An in-vivo cadaver model was developed to quantify intramedullary pressure, temperature, speed and force of reaming. The results showed significant differences in intramedullary pressures with no significant differences in speed and force of reaming.

The purpose of our study was to compare the performance of a new intramedullary reaming device to a contemporary reaming system.

The Synthes Reamer/Irrigator/Aspirator reamer (RIA) produced significantly lower peak and average intramedullary pressures during reaming with no significant differences in speed and force of reaming.

A reaming system with a built-in irrigation/aspiration could possibly reduce the morbidity and mortality associated with the reaming of long bone fractures. There were significantly lower minimum, maximum and average proximal and distal intramedullary pressures with the RIA reamer. There were no significant differences in force or speed of reaming. No temperature changes were noted with either reaming system.

A cadaveric model was developed to compare the RIA reaming system to a contemporary reaming system. Pressures were measured with pressure transducers inserted proximally and distally. Temperatures were measured with thermocouples inserted adjacent to isthmus. Force of reaming was measured with a load cell distally. Speed was calculated from data collected from a linear voltage displacement transducer. Fifteen, matched pairs of frozen, unpreserved femurs were reamed using both reaming systems and the data collected. Canals were reamed to a diameter two centimeters greater than the templated canal size. Data was collected and analyzed with paired t-tests (p< .05).

Embolic material within the cardiovascular system has been shown to increase morbidity and mortality in susceptible individuals. Embolization is related to increased intramedullary pressures. The RIA reamer, as a result of its built-in irrigation/aspiration capacity, produces lower intramedullary pressures. This may have clinical significance.

Funding: This work was supported by Synthes (West Chester, PA)

The objective of this study was to determine if pre-operative gait patterns could predict which patients selected for unicondylar knee replacement (UKR) actually received a UKR or a total knee replacement (TKR). At the time of surgery, ten of the twenty-two UKR candidates presented with extensive degenerative changes and received total knee replacements. We analyzed gait, radiographic, and anthropometric data with a pattern recognition technique designed to detect biomechanical differences between the two groups. The groups were indistinguishable clinically, and radiographically, yet the pattern recognition technique identified features that completely separated the two groups based on the biomechanical differences.

The objective of this study was to determine if pre-operative gait patterns could predict which patients selected for UKR actually received a UKR or a TKR.

The UKR and TKR groups were indistinguishable visibly, clinically, and radiographically, yet the pattern recognition technique employed in this analysis identified features that completely separated the two groups.

Biomechanical differences between the pre-operative groups could lead to more accurate diagnosis of unicompartmental knee OA as well as further understanding of the pathomechanics of knee OA.

Twenty-two patients were initially diagnosed with unicompartmental knee OA of the medial side, and prescribed to receive unicompartmental knee replacements (UKR). At the time of surgery, ten of the twenty-two UKR candidates presented with more extensive degenerative changes and received total knee replacements (TKR). We measured gait data including knee joint angles forces and moments, velocity, stride length, stance percentage, and stance time as well as body mass index. Furthermore radiographic measures were taken including the Hip Knee Ankle (HKA) angle, the standing knee flexion angle, and the medial and lateral condyle joint spaces.

The data were analysed using a pattern recognition technique that used principal component analysis to extract features from the data and discriminant analysis to separate the two groups.

The discriminant function completely separated the UKR and TKR patients based on their pre-operative data. The most discriminatory feature represented a difference in early swing phase in the knee internal rotation moments.