R.H. Lidtke

Effects of specialized footwear on joint loads in osteoarthritis of the knee

OBJECTIVE Elevated dynamic joint loads have been associated with the severity and progression of osteoarthritis (OA) of the knee. This study compared the effects of a specialized shoe (the mobility shoe) designed to lower dynamic loads at the knee with self-chosen conventional walking shoes and with a commercially available walking shoe as a control. METHODS Subjects with knee OA were evaluated in 2 groups. Group A (n = 28) underwent gait analyses with both their self-chosen walking shoes and the mobility shoes. Group B (n = 20) underwent gait analyses with a control shoe and the mobility shoe. Frontal plane knee loads were compared between the different footwear conditions. RESULTS Group A demonstrated an 8% reduction in the peak external knee adduction moment with the mobility shoe compared with self-chosen walking shoes (mean +/- SD 49 +/- 0.80 versus 2.71 +/- 0.84 %BW x H; P < 0.05). Group B demonstrated a 12% reduction in the peak external knee adduction moment with the mobility shoe compared with the control shoe (mean +/- SD 2.66 +/- 0.69 versus 3.07 +/- 0.75 %BW x H; P < 0.05). CONCLUSION Specialized footwear can effectively reduce joint loads in subjects with knee OA, compared with self-chosen shoes and control walking shoes. Footwear may represent a therapeutic target for the treatment of knee OA. The types of shoes worn by subjects with knee OA should be evaluated more closely in terms of their effects on the disease.

Foot center of pressure and medial knee osteoarthritis

BACKGROUND We sought to determine whether symptomatic medial knee osteoarthritis is associated with aberrant loading across the foot during gait. METHODS Twenty-five individuals with medial knee osteoarthritis were compared with 25 controls. Knee radiographs and Western Ontario and McMaster Universities Arthritis Index questionnaires were obtained. Participants walked barefoot over pressure sensors, and the center-of-pressure trace was plotted against the axis of the foot, and a center-of-pressure index was calculated. RESULTS The center-of-pressure indices in the medial knee osteoarthritis group demonstrated high lateral loading compared with the central center-of-pressure pattern in controls (P < .001). There was a correlation between the severity of pain and the center-of-pressure index in patients with medial knee osteoarthritis but no correlation between center of pressure and radiographic severity. CONCLUSIONS The plantar pressure patterns of patients with medial knee osteoarthritis demonstrated greater loading of the lateral aspect of the foot during the contact and midstance phases of gait but not during propulsion compared with those of controls, suggesting that loading patterns in the feet are related to osteoarthritis in the knee.

The labrum of the calcaneocuboid joint

The authors describe a previously unreported anatomical structure in the calcaneocuboid joint of the foot and discuss the clinical significance. Fibroadipose synovial folds or labra are present in different locations throughout the calcaneocuboid joint of the foot. They appear to be wedge-shaped infections attached to the joint capsule in areas of incongruent joint spaces. Their surface is covered with synovial cells with a highly vascular loose connective tissue sublayer. Nerve fibers were seen in association with the joint capsule, but not within the V-shaped labrum. The clinical significance of the presence of the labrum is discussed, but their function is uncertain. These structures can project up to half the joint distance and have the possibility of producing impingement syndromes, or even tears. Since they are covered with two to three layers of synoviocytes, they also have the ability to produce a synovitis. The labrum can be identified using MRI, and once their presence is known arthroscopic repair of these structures is theoretically possible.

402 “MOBILITY” FOOTWEAR REDUCES DYNAMIC LOADS IN SUBJECTS WITH OSTEOARTHRITIS OF THE KNEE

Purpose: Dynamic joint loading is important in the pathophysiology of osteoarthritis (OA) of the knee, and the prevalence and progression of knee OA are known to be associated with high dynamic loading. We have previously demonstrated that in subjects with OA of the knee, walking barefoot significantly decreases peak knee loads compared to walking with standard walking shoes (Arthritis Rheum 54:2923, ’06). These results suggest a potential biomechanical advantage of “natural foot mobility” for lower extremity joint loading. Subsequently, we designed a shoe to incorporate essential features of natural foot motion. Here, we compare both peak and overall knee loads when walking with this “mobility” shoe compared to walking with conventional walking shoes. Methods: Thirty-one subjects with radiographic and symptomatic knee OA underwent gait analyses using an optoelectronic camera system and multi-component force plate. Subjects were evaluated for gait while 1) wearing a “mobility” shoe, designed to provide maximum foot flexibility and motion and 2) wearing their self-chosen conventional walking shoes. Subjects walked at their normal walking speed, and comparisons were performed on runs matched for speed. The primary endpoints for the study were gait parameters that reflected the extent of medial compartment knee loading and included the peak external knee adduction moment (PAddM) and the adduction angular impulse (AddImp). The PAddM is the external adduction moment of greatest magnitude during the stance phase of the gait cycle. The AddImp is the integral of the knee adduction moment over time and has recently been shown to be more sensitive than the PAddM in predicting the radiographic severity of medial compartment knee OA. Paired t-tests were used to compare differences in these parameters during the two footwear conditions. Results: 27 females and 4 males were evaluated, with mean age (±SD) of 61±11 years. There were no significant differences in speed during the walking conditions (1.16 ± 0.23 vs 1.15 ± 0.25 m/sec, p=0.842). There was an 8% reduction in the PAddM (2.73±0.76 vs 2.51±0.80 %BW*ht, p<0.001) and a 7% reduction in the AddImp (0.96±0.45 vs 0.89±0.45 %BW*ht, p<0.016) with the “mobility” shoe compared to subjects’ conventional walking shoes. Conclusions: This study demonstrates that a shoe designed to incorporate the biomechanical advantages of barefoot walking effectively reduces dynamic knee loads during gait. In light of these findings, closer examination of the design and biomechanical effects of modern footwear on the prevalence and progression of lower extremity OA is warranted.

Mechanical Comparison of Cortical Screw Fixation Versus Locking Plate Fixation in First Metatarsal Base Osteotomy

The oblique closing base wedge osteotomy has been used for surgical treatment of moderate to severe hallux valgus deformities with an intermetatarsal angle typically greater than 15°. Several postoperative complications have been identified that relate to failure of the fixation construct used to fixate the osteotomy, especially when that construct has been subjected to a vertical load. We performed a mechanical analysis comparing 2 constructs used to fixate oblique osteotomies of the first metatarsal using composite first metatarsals. An oblique base osteotomy was uniformly performed on 40 composite first metatarsals. Of the 40 specimens, 20 were fixated with a locking plate construct and 18 with a cortical screw construct, consisting of an anchor and compression screw (2 specimens from the latter group were excluded because of hinge fracture). Each specimen was loaded in a materials testing machine to measure the maximum load at construct failure when a vertical force was applied to the plantar aspect of the metatarsal head. The mean load to failure for the locking plate construct was significantly greater than the cortical screw construct (190.0 ± 70 N versus 110.3 ± 20.3 N, p < .001). Our study results have demonstrated that the locking plate construct was able to withstand a significantly greater vertical load before failure than was the 2-cortical screw construct in oblique osteotomies performed at the base of composite first metatarsals.

Long-term effects of lateral wedge orthotics on hip and ankle joint space widths.

BACKGROUND Lateral wedge insoles have been used for the treatment of medial knee osteoarthritis (OA) and have been shown to reduce loading of the medial compartment of the knee. However, as the entire lower extremity acts as a single kinetic chain, altering the biomechanics of the knee may also have significant effects at the ankles or hips. We aimed to evaluate the effects of lateral wedge orthotics on ankle and hip joints, compared to neutral orthotics, by assessing the changes in joint space width (JSW) during 36 months of continuous use. METHODS We prospectively enrolled 109 subjects with symptomatic osteoarthritis of the medial knee according to the American College of Rheumatology criteria. The trial was double blind and patients were randomized to either wedged or neutral orthotic shoe inserts. Hip and ankle JSWs were quantified using plain radiographies at baseline and at 36-months follow-up. FINDINGS 45 patients completed the 36 month study. 31 of those who completed the study were using the lateral wedge versus 14 were using neutral orthotics. 2 patients in the wedge group had missing radiographs and were not included in the JSW analyses. There were no significant differences between the wedge and the neutral orthotics groups in the magnitude of JSW change at either the hip or the ankles at 36 month. INTERPRETATION We found no significant adverse effects of the lateral wedges on ankles or hips. (ClinicalTrials.gov NCT00076453).