Nancy J. Kadel

The effect of walking speed on center of mass displacement

The movement of the center of mass (COM) during human walking has been hypothesized to follow a sinusoidal pattern in the vertical and mediolateral directions. The vertical COM displacement has been shown to increase with velocity, but little is known about the mediolateral movement of the COM. In our evaluation of the mediolateral COM displacement at several walking speeds, 10 normal subjects walked at their self-selected speed and then at 0.7, 1.0, 1.2, and 1.6 m/s in random order. We calculated COM location from a 15-segment, full-body kinematic model using segmental analysis. Mediolateral COM displacement was 6.99 +/- 1.34 cm at the slowest walking speed and decreased to 3.85 +/- 1.41 cm at the fastest speed (p < 0.05). Vertical COM excursion increased from 2.74 +/- 0.52 at the slowest speed to 4.83 +/- 0.92 at the fastest speed (p < 0.05). The data suggest that the relationship between the vertical and mediolateral COM excursions changes substantially with walking speed. Clinicians who use observational gait analysis to assess walking problems should be aware that even normal individuals show significant mediolateral COM displacement at slow speeds. Excessive vertical COM displacement that is obvious at moderate walking speeds may be masked at slow walking speeds.

Prosthesis use in persons with lower- and upper-limb amputation

This study identified clinical (e.g., etiology) and demographic factors related to prosthesis use in persons with upper- and lower-limb amputation (ULA and LLA, respectively) and the effect of phantom limb pain (PLP) and residual limb pain (RLP) on prosthesis use. A total of 752 respondents with LLA and 107 respondents with ULA completed surveys. Factors related to greater use (hours per day) for persons with LLA included younger age, full- or part-time employment, marriage, a distal amputation, an amputation of traumatic etiology, and an absence of PLP. Less use was associated with reports that prosthesis use worsened RLP, and greater prosthesis use was associated with reports that prosthesis use did not affect PLP. Having a proximal amputation and reporting lower average PLP were related to greater use in hours per day for persons with an ULA, while having a distal amputation and being married were associated with greater use in days per month. Finally, participants with LLA were significantly more likely to wear a prosthesis than those with ULA. These results underscore the importance of examining factors related to prosthesis use and the differential effect that these variables may have when the etiology and location of amputation are considered.

Reliability of the Foot Function Index: A Report of the AOFAS Outcomes Committee

Background: There currently is no widely used, validated, self-administered instrument for measuring musculoskeletal functional status in individuals with nonsystemic foot disorders. The purpose of this paper was to report on the assessment of reliability of one of these instruments. We wanted to determine if the Foot Function Index (FFI), which has been validated in rheumatoid patients without fixed foot deformity or prior foot surgery, would be reliable for a population of patients with foot complaints without systemic disease. Methods: Patients were recruited from five orthopaedic offices where the physicians were members of the American Orthopaedic Foot and Ankle Society. Patients were asked to complete the FFI at the time of their initial office visit and then were givena second copy to complete and return by mail 1 week after their visit. Results: Ninety-six patients completed the first questionnaire, and 54 patients completed the second. Reliability in this population was acceptable with an average of 23.5% of the patients providing retest values within one point of the initial response and an average of 45.3% of the patients providing the same response, for a total of 68.8% of all respondents answering within one point between their initial and second questionnaire. In two of the three categories, there were frequent nonresponses or no applicable responses. Four questions, two in the pain section and two in the activity limitation section, generated 20% or more of the nonapplicable answers. Conclusions: The FFI appears to be a reasonable tool for low functioning individuals with foot disorders. It may not be appropriate for individuals who function at or above the level of independent activities of daily living.

Effect of foot and ankle position on tarsal tunnel compartment pressure.

Tarsal tunnel intracompartment pressures were determined in 10 fresh-frozen normal human adult cadaver specimens. With the foot and ankle held in mild plantarflexion and neutral eversion-inversion, mean tarsal tunnel pressure was minimal (2 ± 1 mmHg). However, when the foot and ankle were positioned in full eversion, mean tarsal tunnel pressure increased to 32 ± 5 mmHg (P ≤ 0.005); in full inversion, mean pressure increased to 17 ± 5 mmHg (P ≤ 0.05). There was no significant difference in mean tarsal tunnel pressure between the everted and inverted positions. These results support the hypothesis that increased pressure within the tarsal tunnel when the foot is moved into the everted or inverted position may aggravate posterior tibial nerve entrapment. These findings may also provide an explanation for clinically observed aggravation of symptoms in these positions, night pain, and improvement of symptoms with neutral immobilization in some patients with tarsal tunnel syndrome.

Perioperative Medication Management for the Patient With Rheumatoid Arthritis

Abstract The treatment of rheumatoid arthritis has improved dramatically in recent years with the advent of the latest generation of diseasemodifying antirheumatic drugs. Despite these advances, in some patients inflammation is not diminished sufficiently to prevent irreversible musculoskeletal damage, thus requiring surgical intervention to reduce pain and improve function. In these cases, the orthopaedic surgeon frequently encounters patients on a drug regimen consisting of nonsteroidal anti‐inflammatory drugs, glucocorticoids, methotrexate, and biologic agents (diseasemodifying antirheumatic drugs). Consultation with a rheumatologist is recommended, but the surgeon also should be aware of these medications that could potentially affect surgical outcome. Prudent perioperative management of these drugs is required to optimize surgical outcome. A balance must be struck between minimizing potential surgical complications and maintaining disease control to facilitate postoperative rehabilitation of patients with rheumatoid arthritis.

Regional Foot Pressure During Running, Cutting, Jumping, and Landing

Background Evaluating shoes during sport-related movements may provide a better assessment of plantar loads associated with repetitive injury and provide more specific data for comparing shoe cushioning characteristics. Hypothesis Accelerating, cutting, and jumping pressures will be higher than in straight running, differentiating regional shoe cushioning performance in sport-specific movements. Study Design Controlled laboratory study. Materials and Methods Peak pressures on seven anatomic regions of the foot were assessed in 10 male college athletes during running straight ahead, accelerating, cutting left, cutting right, jump take-off, and jump landing wearing Speed TD and Air Pro Turf Low shoes (Nike, Beaverton, Ore). Pedar insoles (Novel, Munich, Germany) were sampled at 99 Hz during the 6 movements. Results Cutting and jumping movements demonstrated more than double the pressure at the heel compared with running straight, regardless of shoe type. The Air Pro Turf showed overall lower pressure for all movement types (P < .0377). Cutting to the left, the Air Pro Turf shoe had lower heel pressures (36.6 ± 12.5 N/cm2) than the Speed TD (50.3 ± 11.2 N/cm2) (P < .0001), and the Air Pro Turf had lower great toe pressures than the Speed TD (44.8 ± 8.1 N/cm2 vs 54.4 ± 8.4 N/cm2; P = .0002). The Air Pro Turf also had significantly lower pressures than the Speed TD at the central forefoot during acceleration (38.2 ± 8.3 N/cm2 vs 50.8 ± 7.4 N/cm2; P <.0001). Conclusion Sport-related movements load the plantar surface of the foot more than running straight. Shoe cushioning characteristics were more robustly assessed during sport-related movements (4 significant results detected) compared with running straight (1 significant result detected). Clinical Relevance There is an interaction between shoe cushioning characteristics and sport-related movements that may influence plantar pressure and repetitive stress injuries.

Anterior impingement syndrome in dancers.

Anterior impingement is a common problem in dancers occurring primarily secondary to the repetitive forced ankle dorsiflexion inherent in ballet. Symptoms generally occur progressively and may respond to conservative treatment including addressing biomechanical faults that contribute to the problem. As impingement progresses, movements essential to ballet may become impossible and arthroscopic ankle surgery is often effective for both diagnosis and treatment, allowing athletes to return to dance.

Stability of Lisfranc joints in ballet pointe position.

Background: Ballerinas develop stress fractures at the second metatarsal base associated with dancing en pointe. The purpose of this study was to evaluate the relative importance of the pointe shoe and the tarsometatarsal ligaments in Lisfranc joint stability en pointe. Methods: Eleven cadaver feet were dressed with pointe shoes, loaded in foot flat with ligaments intact, and loaded en pointe before and after sequential sectioning of the dorsal, interosseous, and plantar ligaments between the first and second metatarsals and cuneiforms. Relative motion between the first and second metatarsals and cuneiforms was determined radiographically. Results: No significant displacement of the Lisfranc joints occurred when the shod foot with intact ligaments was loaded in the foot flat or en pointe positions. Serial sectioning of the ligaments from dorsal to plantar in the shod foot en pointe demonstrated no change in alignment after the dorsal and interosseous ligaments were cut, but a significant change in alignment between the second metatarsal and second cuneiform was noted after the plantar ligament was cut (p < 0.0001). Removal of the pointe shoe after cutting the ligaments and applying a minimal (1 to 2 kg) load resulted in complete subluxation and diastasis through the first-second intermetatarsal and intercuneiform region. Replacing the shoe improved alignment en pointe with similar loading. Conclusions: Both the pointe shoe and Lisfranc ligaments are important for Lisfranc region stability in feet en pointe. The plantar ligaments are major stabilizers of the Lisfranc region in the loaded, shod foot en pointe. Selection of a pointe shoe with adequate support may limit susceptibility to stress fracture of the second metatarsal base in ballerinas.

The Efficacy of Two Methods of Ankle Immobilization in Reducing Gastrocnemius, Soleus, and Peroneal Muscle Activity during Stance Phase of Gait

Background: Immobilization to limit muscle activity is a common therapeutic and posttreatment event. There are potential time and resource savings if a prefabricated boot can replace a custom applied cast. The purpose of this study was to determine if muscle activity reduction is similar using a fiberglass cast versus a prefabricated (Aircast FoamWalker) boot. Methods: Surface EMG data were recorded from the gastrocnemius, soleus, and peroneals of 12 normal adults while walking barefoot, in a fiberglass cast with a cast shoe (cast), and while wearing an Aircast FoamWalker (boot). Subjects walked at their self-selected speed for 10 trials in each condition, and the order of barefoot, cast, and boot was randomly assigned. The data were rectified, integrated across stance phase and normalized to a percent of each subjects barefoot mean integrated EMG (iEMG) value. For each muscle, a linear mixed-effects statistical model (subject by trial by condition) was utilized to determine if iEMG activity levels were reduced by immobilization compared to barefoot walking. Results: Activity for all muscles was significantly lower in the boot compared with barefoot (p <.05). The cast iEMG levels were significantly different from barefoot for the soleus and peroneals (p <.05). Gastrocnemius activity was significantly decreased in the boot when compared with the cast (p <.0001). The greater reduction in iEMG levels for the boot indicates that it is superior to a fiberglass cast in reducing gastrocnemius muscle activity during the stance phase of gait. Conclusions: The data show that a prefabricated boot is as effective as a custom applied cast in reducing soleus and peroneal muscle iEMG during stance phase. The boot was more effective in reducing gastrocnemius activity when compared to the cast. Clinical Relevance: This study suggests that a prefabricated boot may be used in place of a custom cast when the goal of treatment is to limit muscle activity of the leg.

Alternative to the modified jones procedure: outcomes of the flexor hallucis longus (FHL) tendon transfer procedure for correction of clawed hallux.

Background: The modified Jones procedure is the traditional operative procedure for correction of a clawed hallux, although the deformity may be caused by over-pull of one of three different muscles. In this study we present the radiographic and functional outcomes of flexor hallucis longus (FHL) tendon transfer as treatment for clawed hallux. The transfer is performed by drawing two thirds of the FHL tendon up through a drill hole in the proximal phalanx and then suturing it medially back to the remaining third. Methods: We retrospectively identified 19 patients (22 feet) who had FHL tendon transfer for correction of clawed hallux over a period of 5 years. Followup was an average of 51.0 (range 6 to 74; ± 3.8) months after the procedure. Outcome and patient satisfaction were determined using the Long-Form Musculoskeletal Function Assessment (MFA) score. Patients were asked whether they were satisfied, somewhat satisfied, or dissatisfied with the overall outcome and were asked about shoewear limitations. Preoperative and postoperative radiographs were evaluated in 15 patients (17 feet). We measured the hallux valgus and interphalangeal (IP) angles on the anteroposterior (AP) radiographs. On the lateral view we measured the angle of the IP joint, the metatarsophalangeal (MTP) joint, and the talometatarsal angle. Statistical analysis was done using a repeated measures ANOVA (p < 0.05). Results: On the lateral radiographs, the hallux IP joint angle (p < 0.0012; n = 15) and hallux MTP joint angle (p < 0.0265; n = 15) were significantly reduced postoperatively. On AP radiographs, the hallux valgus angle (p < 0.0334) was significantly reduced; however, the IP angle and the talometatarsal angle were not significantly different after surgery. Patients had an average MFA score of 14.6 (±3.8 standard error, range 1 to 35; n = 19). Thirteen patients were fully satisfied and six were somewhat satisfied with the overall result of the surgery. Four patients thought that their hallux limited the types of shoes they could wear, while 15 did not. Conclusion: It has been shown that clawed hallux can result from excessive motor function in one of three muscles: FHL tendon, peroneus longus (PL), and extensor hallucis longus (EHL). This study suggests that transfer of part of the tendon of the FHL is an effective alternative operative procedure for correction of clawed hallux.