Short-term cutaneous vasodilatory and thermosensory effects of topical methyl salicylate.

Introduction: Methyl salicylate, the main compound of wintergreen oil, is widely used in topical applications. However, its vascular and thermosensory effects are not fully understood. The primary aim was to investigate the effects of topical methyl salicylate on skin temperature (Tskin), skin microcirculation (MCskin) and muscle oxygen saturation (SmO2) compared to a placebo gel. The secondary aim was to assess thermosensory responses (thermal sensation, thermal comfort) and to explore to which extent these sensations correspond to the physiological responses over time. Methods: 21 healthy women (22.2 ± 2.9 years) participated in this single-blind, randomized controlled trial. Custom-made natural wintergreen oil (12.9%), containing methyl salicylate (>99%) and a placebo gel, 1 g each, were applied simultaneously to two paravertebral skin areas (5 cm × 10 cm, Th4-Th7). Tskin (infrared thermal imaging), MCskin (laser speckle contrast imaging) and SmO2 (deep tissue oxygenation monitoring) and thermosensation (Likert scales) were assessed at baseline (BL) and at 5-min intervals during a 45 min post-application period (T0-T45). Results: Both gels caused an initial decrease in Tskin, with Tskin(min) at T5 for both methyl salicylate (BL-T5: Δ-3.36°C) and placebo (BL-T5: Δ-3.90°C), followed by a gradual increase (p < .001). Methyl salicylate gel resulted in significantly higher Tskin than placebo between T5 and T40 (p < .05). For methyl salicylate, MCskin increased, with MCskin(max) at T5 (BL-T5: Δ88.7%). For placebo, MCskin decreased (BL-T5: Δ-17.5%), with significantly lower values compared to methyl salicylate between T0 and T45 (p < .05). Both gels had minimal effects on SmO2, with no significant differences between methyl salicylate and placebo (p > .05). Thermal sensation responses to topical methyl salicylate ranged from "cool" to "hot", with more intense sensations reported at T5. Discussion: The findings indicate that topical methyl salicylate induces short-term cutaneous vasodilation, but it may not enhance skeletal muscle blood flow. This study highlights the complex sensory responses to its application, which may be based on the short-term modulation of thermosensitive transient receptor potential channels.

Home-Based Nonoperative-Side Quadriceps Neuromuscular Electrical Stimulation Prevents Muscle Weakness Following Anterior Cruciate Ligament Reconstruction.

We compared the effectiveness of a home-based neuromuscular electrical stimulation (NMES) program applied to the quadriceps of the nonoperative side against sham-NMES as a complement to standard rehabilitation on knee extensor neuromuscular function in patients following anterior cruciate ligament (ACL) reconstruction. Twenty-four patients completed the 6 week NMES (n = 12) and sham-NMES (n = 12) post-operative interventions and were tested at different time points for neuromuscular function and self-reported knee function. Isometric, concentric, and eccentric strength deficits (muscle weakness) increased significantly from pre-surgery to 24 weeks post-surgery in the sham-NMES group (p < 0.05), while no significant changes were observed in the NMES group. On the stimulated (nonoperative) side, quadriceps voluntary activation and muscle thickness were respectively maintained (p > 0.05) and increased (p < 0.001) as a result of the NMES intervention, contrary to sham-NMES. Self-reported knee function improved progressively during the post-operative phase (p < 0.05), with no difference between the two groups. Compared to a sham-NMES intervention, a 6 week home-based NMES program applied to the quadriceps of the nonoperative side early after ACL reconstruction prevented the occurrence of knee extensor muscle weakness 6 months after surgery. We conclude that nonoperative-side NMES may help counteract muscle weakness after ACL reconstruction.

Short-term functional advantages after medial unicompartmental versus total knee arthroplasty.

BACKGROUND: There are many uncertainties about the advantages and disadvantages of using unicompartmental (UKA) versus total knee arthroplasty (TKA) to treat patients with knee osteoarthritis. It is important to have sufficient early postoperative quadriceps strength for long-term, self-reported and gait-related outcomes after knee arthroplasty, but very limited comparative data exist regarding UKA and TKA patients. METHODS: This study assessed isometric quadriceps strength, spatio-temporal gait parameters (walking speed, step length, single-limb support phase) and self-reported outcomes (pain, function, stiffness) in 18 TKA and 18 UKA patients six months after surgery, as well as in 18 healthy controls. RESULTS: Quadriceps strength of TKA, but not of UKA patients, was lower than that of controls (P < 0.05). UKA patients demonstrated better gait function in terms of a longer single-limb support phase than TKA patients (P < 0.01), which agreed with better self-reported pain (P < 0.05), function (P < 0.01) and stiffness (P < 0.05) scores compared to TKA patients. CONCLUSIONS: Six months after surgery, UKA patients showed better short-term quadriceps strength and gait function compared to TKA patients, together with less self-reported knee pain and stiffness. Patients eligible for UKA may experience less functional impairments compared to those who require TKA.

Explosive and maximal strength before and 6 months after total hip arthroplasty.

Patients with unilateral hip osteoarthritis experience impairments in lower limb muscle function due to pain and disuse of the affected limb. The influence of hip osteoarthritis and subsequent total hip arthroplasty (THA) has mostly been evaluated by maximal strength tests, yet the functionally important explosive strength capabilities of hip and knee muscles are largely unknown. We aimed to evaluate hip and knee explosive and maximal strength in hip osteoarthritis patients before and after THA. Twenty-one patients with unilateral hip osteoarthritis were evaluated before and 6 months after THA. They performed rapid maximal contractions of hip (flexor, extensor, abductor, adductor) and knee (flexor, extensor) muscles, from which explosive and maximal strength asymmetries were evaluated (involved versus uninvolved limb). Before THA, the involved limb showed significantly lower hip flexor, extensor, adductor, and knee extensor explosive and maximal strength compared to the uninvolved limb. Six months after THA surgery, hip flexor, extensor and adductor maximal and explosive strength asymmetries persisted, except for knee extensors. Explosive, but not maximal strength of hip abductors and knee extensors was lower in the involved limb before surgery and the reduced explosive strength capabilities may compromise daily living activities in hip osteoarthritis patients. After hip replacement, explosive strength asymmetries of knee extensors resolved, yet lingering asymmetries in hip flexor muscles should receive focused attention during postoperative rehabilitation. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:425-431, 2018.

Outcome of Hip Impingement Surgery: Does Generalized Joint Hypermobility Matter?

BACKGROUND: Generalized joint hypermobility (JH) might negatively influence the results of surgical femoroacetabular impingement (FAI) treatment, as JH has been linked to musculoskeletal pain and injury incidence in athletes. JH may also be associated with worse outcomes of FAI surgery in thin females. PURPOSE: To (1) determine the results of FAI surgery at a minimum 2-year follow-up by means of patient-reported outcome measures (PROMs) and failure rates, (2) assess the prevalence of JH in FAI patients and its effect on outcomes, and (3) identify other risk factors associated with treatment failure. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: We included 232 consecutive patients (118 females; mean age, 36 years) with 244 hips surgically treated for symptomatic FAI between 2010 and 2012. All patients completed different PROMs preoperatively and at a mean follow-up of 3.7 years. Satisfaction questions were used to define subjective failure (answering any of the 2 subjective questions with dissatisfied/ very dissatisfied and/or didn't help/ made things worse). Conversion to total hip replacement (THR) was defined as objective failure. JH was assessed using the Beighton score. RESULTS: All PROM values significantly ( P < .001) improved from preoperative measurement to follow-up (Oxford Hip Score: 33.8 to 42.4; University of California at Los Angeles Activity Scale: 6.3 to 7.3; EuroQol-5 Dimension Index: 0.58 to 0.80). Overall, 34% of patients scored ≥4 on the Beighton score, and 18% scored ≥6, indicating generalized JH. Eleven hips (4.7%) objectively failed and were converted to THR. Twenty-four patients (10.3%) were considered as subjective failures. No predictive risk factors were identified for subjective failure. Tönnis grade significantly ( P < .001) predicted objective failure (odds ratio, 13; 95% CI, 4-45). There was a weak inverse association ( r = -0.16 to -0.30) between Beighton scores and preoperative PROM values. There were no significant associations between Beighton scores and postoperative PROM values or subjective failure rates, but patients who objectively failed had lower Beighton scores than did nonfailures (1.6 vs 2.6; P = .049). CONCLUSION: FAI surgery yielded favorable outcomes at short- to midterm follow-up. JH as assessed by the Beighton score was not consistently associated with subjective and objective results. Joint degeneration was the most important risk factor for conversion to THR. Although statistical significance was not reached, female patients with no joint degeneration, only mild FAI deformity, and higher Oxford scores at the time of surgery seemed to be at increased risk for subjective dissatisfaction.

Clinical improvement and satisfaction after total joint replacement: a prospective 12-month evaluation on the patients' perspective.

PURPOSE: To determine short-term improvements, satisfaction rates and the patient acceptable symptom state (PASS) after total joint replacement (TJR) for different patient-reported outcome measures (PROMs). METHODS: This prospective cohort study included 426 consecutive patients undergoing total hip (n = 193) or knee arthroplasty (n = 233). The following PROMs were completed before TJR, and at 3, 6 and 12 months after surgery, respectively: WOMAC, Oxford Hip or Knee Score, Lower Extremity Functional Scale, University of California at Los Angeles (UCLA) activity scale and EuroQol-5 dimension (EQ-5D). Satisfaction rates and the PASS thresholds were also assessed. RESULTS: THA patients improved quicker and achieved higher outcome scores than TKA patients. Comorbidities according to the Sangha score were moderately correlated with all PROM values in an inverse direction at all time points (r = -0.27 to -0.47, p < 0.01) in both groups. Satisfaction with the result of surgery improved over time. At 12 months, more than 90 % of the patients were satisfied or very satisfied with the achieved result. The THA group showed a higher proportion of very satisfied patients than the TKA group at all time points. PASS thresholds increased over time for all PROMs except for the UCLA and the EQ-5D in TKA patients. CONCLUSIONS: More than 90 % of the patients will be satisfied 1 year after TJR. THA patients recover faster than TKA patients, i.e., they achieve higher PROM values at earlier follow-up time points. Cutoff values defining a successful result in terms of the PASS could be defined for all PROMs at different time points and can serve as reference for future studies and patient-oriented follow-ups.

Acute effects of multipath electrical stimulation in patients with total knee arthroplasty.

OBJECTIVE: To compare maximal evoked torque, discomfort, and fatigue-related outcomes between multipath neuromuscular electrical stimulation (NMES) and conventional NMES of the quadriceps muscle in patients with total knee arthroplasty (TKA). DESIGN: Randomized, single-blind, crossover study with 2 experimental sessions (multipath NMES, conventional NMES). SETTING: Research laboratory. PARTICIPANTS: Patients (N=20; mean age, 68y) 6 to 12 months after TKA surgery. INTERVENTIONS: None. MAIN OUTCOME MEASURES: We quantified NMES-evoked knee extension torque at the maximally tolerated current intensity, self-reported discomfort, and fatigue induced by NMES intermittent contractions in both conditions. RESULTS: Compared with conventional NMES, multipath NMES resulted in higher evoked torque (33%, P<.001), lower discomfort scores (-39%, P<.001), and less quadriceps muscle fatigue (P=.034). CONCLUSIONS: The use of multiple current pathways distributed to large electrodes allowed multipath NMES to generate stronger contractions and reduce discomfort and fatigue compared with conventional NMES. Therefore, multipath NMES has the potential to be more effective than conventional NMES.

The German Lower Extremity Functional Scale (LEFS) is reliable, valid and responsive in patients undergoing hip or knee replacement.

PURPOSE: To determine the measurement properties of a German version of the Lower Extremity Functional Scale (LEFS) in patients with hip or knee osteoarthritis undergoing total joint replacement (TJR). METHODS: This prospective cohort study included 486 consecutive patients. The LEFS and other self-reported outcome measures were administered at different time points and several classical measurement properties were determined. RESULTS: The German LEFS was highly reliable (ICC 0.98) and internally consistent (CA 0.95). Construct validity was proven by large to very large correlations (r = 0.52-0.91) with all other instruments in the expected directions. Factor analysis using a polychoric correlation matrix revealed two factors at baseline and 6 months explaining about 70% of the total variance. There were no floor or ceiling effects for the total score, but significant floor effects for the single items 16-19 at baseline. The LEFS was highly responsive at 6 months. CONCLUSIONS: The German LEFS proved to be a reliable, valid and responsive tool for the self-assessment of patients undergoing total hip or knee replacement. Nevertheless, the questionnaire seems to summarize more than one construct as highlighted by the factor analysis. Further research seems therefore warranted.

Assessment of quadriceps muscle inactivation with a new electrical stimulation paradigm.

INTRODUCTION: In this study we evaluated the validity of garment-based quadriceps stimulation (GQS) for assessment of muscle inactivation in comparison with femoral nerve stimulation (FNS). METHODS: Inactivation estimates (superimposed doublet torque), self-reported discomfort, and twitch and doublet contractile properties were compared between GQS and FNS in 15 healthy subjects. RESULTS: Superimposed doublet torque was significantly lower for GQS than for FNS at 20% and 40% maximum voluntary contraction (MVC) (P < 0.01), but not at 60%, 80%, and 100% MVC. Discomfort scores were systematically lower for GQS than for FNS (P < 0.05). Resting twitch and doublet peak torque were lower for GQS, and time to peak torque was shorter for GQS than for FNS (P < 0.01). CONCLUSIONS: GQS can be used with confidence for straightforward evaluation of quadriceps muscle inactivation, whereas its validity for assessment of contractile properties remains to be determined.