Lower-extremity kinematics and kinetics differ based on drop vertical jump variation: An assessment of methodology for a return-to-play protocol using motion analysis

BACKGROUND

The drop vertical jump (DVJ) is commonly used in return-to-play evaluations to assess movement quality and risk during a dynamic task. However, across biomechanics literature, a multitude of DVJ variations have been used, influencing the generalizability and potential interpretation of the reported findings.

RESEARCH QUESTION

The purpose of this study was to identify differences in lower extremity kinematics and kinetics between DVJ variations that differ based on horizontal jump distance, verbal instructions, and the use of a jump target.

METHODS

A single-group repeated measures design was used in a laboratory setting. Twenty participants were tested, and three-dimensional angles and moments of the pelvis, hip, knee, and ankle were computed. Wilcoxon signed rank tests were performed to determine differences between DVJ variations.

RESULTS

Reduced knee flexion at initial contact and greater knee extensor moments across the descent phase were observed with increased horizontal jump distance. Additionally, both verbal instructions and a jump target influenced movement strategies at the pelvis, hip, and knee. Ground reaction forces were found to be similar across conditions and jump height following the first landing increased with a target.

SIGNIFICANCE

Although subtle, the biomechanical differences observed between task variations emphasize the importance of standardizing motion analysis protocols for research and clinical decision-making. Given the findings of the current study, the authors recommend using the Half Height variation in patients treated for a knee injury as it will likely be the most indicative of movement quality.

Trunk and lower-extremity kinematics differ based on step-down tap variation: An assessment of methodology for a return-to-play protocol using motion analysis

BACKGROUND

The step-down tap (SDT) is a commonly used task to assess unilateral neuromuscular control and to identify deficient movement patterns of the trunk and lower extremities. However, instruction of the SDT varies greatly in recent reports, which may alter the clinical interpretation of potential movement deficiencies.

RESEARCH QUESTION

The purpose of this study was to identify differences in trunk and lower extremity kinematics between variations of a step-down tap that differ based on step direction, fixing the arms or stance foot, and trial collection methods.

METHODS

This study followed a single-group repeated measures design in a laboratory setting. Three-dimensional angles of the trunk, hip, and knee of 18 participants were evaluated at 60 degrees of knee flexion and at maximum squat depth during six SDT variations. Wilcoxon signed rank tests were performed to determine the effects of an anterior verse lateral step direction, a fixed arm or stance foot position, and an individual verse continuous trial collection method.

RESULTS

Knee flexion, external pelvic rotation, and external trunk rotation were greater in the anterior SDT, while the lateral SDT elicited greater pelvic tilt and hip flexion. Additionally, overall squat depth was greater across participants during the anterior SDT. Few clinically significant differences (≥3°) were observed due to fixing arm or stance foot position, and no differences were identified based on trial collection methods.

SIGNIFICANCE

The standardization of task instructions for motion analysis protocols utilized for research purposes and/or clinical decision-making is crucial. Specifically, for the SDT, the authors recommend using the anterior step direction. A fixed arm and stance foot position is not necessary, and trials may be collected individually or continuously based on convenience for a small number of repetitions.

Factors medical students use to select orthopedic surgery residency positions

This study reviewed all applications to our residency program and all interviewees completed a standardized questionnaire. Data was collected on applicants' educational background, knowledge of the residency program, and geographical considerations. All rotating applicants (21/46) knew the correct name of the chairman and program director, and knew the program size, compared with non-rotating applicants (25/46). Applicants applied to the programs within our city limits more often (80%) than to programs furthest from the city limits (63%). These data suggest that factors including size, rotations, research, and operative experience, may be less important than geographical considerations for medical students choosing an orthopedic surgery residency.

Continuous passive motion after tenolysis in hand therapy patients: a retrospective study

Continuous passive motion (CPM) is a common adjunct to the postoperative therapy program. Use of CPM has been advocated for a variety of diagnoses in hand rehabilitation. This retrospective study compares two groups of patients who underwent digital tenolysis (and/or capsulectomy) and evaluates the use of CPM in their postoperative therapeutic management. Both groups had initial injuries of fractures, tendon lacerations, and/or crush injuries resulting in surgical intervention. After therapeutic rehabilitation, the patients failed to gain satisfactory active ROM and elected to proceed with a secondary surgical procedure. Fifteen patients (19 digits) who used CPM machines in addition to their home exercise program were compared to 21 patients (24 digits) who did not use CPM. Primary outcome comparisons for this study were change in total active motion (TAM) over time (preoperative to discharge from therapy), duration of therapy, and total number of therapy visits. There was no significant difference (F=1.16, p=0.29) in the change in TAM for patients using CPM (39.89 degrees ) compared to those not using CPM treatment (31.83 degrees ). Furthermore, CPM users were seen for significantly more therapy sessions than non-CPM users (25.7 therapy visits compared to 18.54 therapy visits). Rehabilitation lasted approximately the same amount of weeks for both groups (CPM users 10.21 weeks vs. non-CPM users 11.42 weeks).

Timed motor test for wheelchair users: initial development and application in children with spinal cord injury

OBJECTIVE

The objective of this study was to describe the development and preliminary results of reliability testing of the timed motor test (TMT), a performance-based measure of functional status for children with a spinal cord injury (SCI) who use a manual wheelchair. This study will also provide pilot data using the TMT to examine the impact of thoracolumbosacral orthoses (TLSO) on function in children with a SCI.

STUDY DESIGN

Cross-sectional observational study. METHODS/PARTICIPANTS: This study enrolled 11 subjects with SCI. The TMT consisted of donning a shirt, donning pants, even transfers, uneven transfers, and propelling a wheelchair 80 feet and up a ramp of 45 feet. Nine subjects completed the TMT with and without a TLSO, and 6 subjects (4 of whom also completed the TMT with and without a TLSO) completed the reliability testing.

RESULTS

Except for donning pants, the intertester and intratester reliability of the TMT was fair-to-good with intraclass correlation coefficients (ICCs) of 0.60 or greater. When wearing a TLSO, participants were slower at donning a shirt, donning pants, performing even and uneven transfers, and hallway propulsion (P < 0.05). There was a preference for not wearing a TLSO for dressing and transfer skills.

CONCLUSION

In general, the TMT for wheelchair users had fair-to-good intertester and intratester reliability. Based on these pilot data, there was an increase in time to complete several functional tasks because of the use of a TLSO as measured by the TMT in children with a SCI.

Ionization and adsorption of a series of local anesthetics in detergent micelles: studies of drug fluorescence

The goal of this study was to compare the behavior of structurally homologous local anesthetics (LAs) adsorbed to a simplified membrane model. Interactions of LAs with micelles made from negative and neutral detergents were assayed by drug fluorescence. Micellar:drug affinity, equivalent dielectric constant and pKa of bound LAs were assessed for procaine, tetracaine, procainamide, benzocaine and aminoparabenzyldiethylamine, a procaine homologue containing an alkyl chain instead of an ester bond. Shifts in maximum emission wavelength and changes in fluorescence intensity showed that 1) increased LA hydrophobicity (expressed as octanol:buffer partition coefficient) corresponded to increased affinity for all micelles; 2) protonated species of LA were bound more tightly than neutral species to negative micelles, but less tightly to unchanged micelles; 3) drugs with larger dipole moments (amide < ester < alkyl) bind less tightly to micelles than those with smaller dipoles; 4) Larger dipole moments of LAs also result in a larger equivalent dielectric constant around the micellar-bound LAs, meaning that the LA binds at a shallower depth from the micelle surface; and 5) binding the neutral micelles lowers the pKa but binding to negatively charged micelles raises the pKa (due to the concentrating effects of surface charge on H+). The results provide a picture of interfacial adsorption of LAs in a relatively simple system that should allow interrelation of the dipole field contributions to LA behavior in phospholipid bilayers.

Fundamental properties of local anesthetics. II. Measured octanol:buffer partition coefficients and pKa values of clinically used drugs

Because local anesthetic molecules interact with ion channel proteins embedded in membranes to effect impulse blockade, and because their clinical potency often depends on both vascular absorption and distribution into the tissue surrounding the site of deposition, the ability to partition into these various compartments is an important determinant of local anesthetic action. Therefore, the hydrophobic nature of local anesthetics used clinically was characterized by the octanol:buffer partition coefficients of their charged (P+) and neutral (Po) species. This was accomplished by previously described optical methods in which direct spectrophotometric measurement of both the pH-dependent distribution coefficient (Q) and of the ionization permit calculation of the pKa and partition coefficients. The rates of alkaline hydrolysis of ester-linked molecules also were measured to assess potential interference of such hydrolysis with the physicochemical assays. Results indicate that the hydrophobicity of a local anesthetic is increased by manipulation of the molecular structure at three sites: (a) the aromatic ring; (b) the intermediate linking group; and (c) the tertiary amine. Po for the agents studied was 10(3)-10(5) times greater than P+. Although there is no systematic relationship between hydrophobicity and pKa, the latter is greater with ester-linked (pKa = 8.59-9.30) than with amide-linked (pKa = 7.92-8.21) local anesthetics. All of the charged species, with the exception of bupivacaine, selectively partition into the aqueous environment (P+ less than 1.0). The temperature dependence of partitioning of the local anesthetics, measured at 25 and 36 degrees C, indicates an entropy-driven hydrophobic uptake. Solutions buffered with bicarbonate and including 5% CO2 showed the same local anesthetic partitioning as that of CO2-free solutions, suggesting that potentiation of impulse blockade by CO2 is not due to increased membrane uptake. Correlations of physicochemical properties of local anesthetics with potencies on isolated nerve confirm that the more potent local anesthetics have greater octanol:buffer partition coefficients, and that the ester-linked local anesthetics are more potent than their amide-linked counterparts having the same hydrophobicities. The correlations of structure with potency also suggest that the extracellular protonated species may contribute to impulse blockade.