Role of the posterior deep deltoid ligament in ankle fracture stability: A biomechanical cadaver study.

BACKGROUND: The deltoid ligament is a key component of ankle fracture stability. Clinical tests to assess deltoid ligament injury have low specificity. In supination external-rotation (SER) type-IV ankle fractures, there is either a medial malleolus fracture or deltoid ligament injury. These injuries are often considered unstable, requiring surgical stabilisation. We look to identify the anatomical basis for this instability. This study investigates the anatomical basis for such instability by re-creating SER type ankle fractures in a standardised cadaveric study model, investigating the anatomical basis for such instability. AIM: To investigate the anatomical basis for fracture instability in SER type ankle fractures. METHODS: Four matched pairs of cadaveric limbs were tested for stability both when axially loaded and under external rotation stress. Four matched pairs of cadaveric limbs (8 specimens) were tested for stability when axially loaded to 750 N with a custom rig. Specimens were tested through increasing stages of SER injury in a stepwise fashion before restoring the lateral side with open reduction and internal fixation (ORIF). Clinical photographs and radiographs were recorded at each step. We defined instability in accordance with well accepted radiological parameters: > 4 mm medial clear space opening on a mortise-view radiograph or > 7 degrees of talar tilt. RESULTS: All specimens with an intact posterior deep deltoid ligament were stable. Once the posterior deep deltoid ligament was sectioned there was instability in all specimens. Stabilisation of the lateral side prevented talar shift, but not talar tilt. CONCLUSION: If the posterior deep deltoid ligament is intact then SER fractures can be managed without surgery. If the posterior deep deltoid is incompetent, ORIF and cautious rehabilitation is recommended because the talus can still tilt in the mortise.

A voluntary activation deficit in m. abductor hallucis exists in asymptomatic feet.

M. abductor hallucis (AbH) is the strongest intrinsic foot muscle and its dysfunction underlies various foot disorders. Attempts to strengthen the muscle by voluntary exercises are constrained by its complex morphology and oblique mechanical action, which leads to an inability even in asymptomatic individuals to fully activate AbH. This study investigated the extent and magnitude of this inability whilst also providing preliminary evidence for the virtue of targeted sub-maximum neuromuscular electrical stimulation (NMES) as a countermeasure for an AbH activation deficit. The voluntary activation ratio (VAR) was assessed via the twitch interpolation technique in the left AbH of 13 healthy participants during maximum voluntary 1st metatarsophalangeal joint flexion-abduction contractions (MVC). Participants were grouped ("able" or "unable") based on their ability to fully activate AbH (VAR ≥ 0.9). 7 s-NMES trains (20 Hz) were then delivered to AbH with current intensity increasing from 150% to 300% motor threshold (MT) in 25% increments. Perceived comfort was recorded (10 cm-visual analogue scale; VAS). Only 3 participants were able to activate AbH to its full capacity (able, mean (range) VAR: 0.93 (0.91-0.95), n = 3; unable: 0.69 (0.36-0.83), n = 10). However, the maximum absolute forces produced during the graded sub-maximum direct-muscle NMES protocol were comparable between groups implying that the peripheral contractility of AbH is intact irrespective of the inability of individuals to voluntary activate AbH to its full capacity. These findings demonstrate that direct-muscle NMES overcomes the prevailing inability for high voluntary AbH activation and therefore offers the potential to strengthen the healthy foot and restore function in the pathological foot.

Direct muscle electrical stimulation as a method for the in vivo assessment of force production in m. abductor hallucis.

In vivo assessment of the force-generating capacity of m. abductor hallucis (AbH) is problematic due to its combined abduction-flexion action and the inability of some individuals to voluntarily activate the muscle. This study investigated direct muscle electrical stimulation as a method to assess isometric force production in AbH about the 1st metatarsal phalangeal joint (1MPJ) at different muscle-tendon lengths, with the aim of identifying an optimal angle for force production. A 7 s stimulation train was delivered at 20 Hz pulse frequency and sub-maximal (150% motor threshold) intensity to the AbH of the left foot in 16 participants whilst seated, and with the Hallux suspended from a force transducer in 0°,5°,10°,15° and 20° 1MPJ dorsal flexion. Reflective markers positioned on the foot and force transducer were tracked with 5 optical cameras to continuously record the force profile and calculate the external 1MPJ joint flexion moment at each joint configuration. A parabolic relationship was found between AbH force production and 1MPJ configuration. The highest 1MPJ joint moments induced by electrical stimulation were found between 10° and 15° of Hallux dorsal flexion. However, the joint angle (p < 0.001; η2 = 0.86) changed significantly across all but one 1MPJ configurations tested during the stimulation-evoked contraction, resulting in a significant change in the corresponding external moment arm (p < 0.001; η2 = 0.83). Therefore, the changes in joint geometry during contraction should be accounted for to prevent an underestimation of the resulting joint moment. We conclude that direct muscle electrical stimulation combined with dynamometry offers a robust method for standardised assessment of AbH sub-maximal isometric force production.

Trampoline Park Injuries and Their Burden on Local Orthopaedic and Emergency Services.

OBJECTIVE: To investigate the incidence of trampoline park injuries (TPIs) at a local recreational facility and to quantify the burden on emergency and orthopaedic services at our institute. METHODS: All patients that presented to the Emergency Department (ED) from the trampoline park via ambulance from July 2014 to November 2015 were included in the study. Patients' medical records were reviewed for clinical details including date, location and type of injury, treatment received, length of stay and outpatient follow-up. A cost analysis was performed to estimate the financial impact of each injury. RESULTS: A total of 71 patients were included in the study, with a mean age of 20 (7-48). Soft tissue sprains (n=29, 41%) and fractures (n=25, 35%) were the most common injuries, with the majority occurring in the lower limb. Two patients sustained open tibial fractures necessitating transfer to level 1 trauma centres. Fourteen patients (20%) underwent surgery, predominantly requiring open reduction and internal fixation. Overall, 18 patients (25%) required admission to hospital with mean length of stay of 2 days. The cost for pre-hospital, emergency and in-patient care amounted to over £80,000. CONCLUSION: TPIs pose a significant financial cost for local orthopaedic and emergency services. Contrary to studies evaluating home trampoline injuries, the majority of fractures at trampoline parks occurred in the lower limbs. Improved injury prevention strategies are required to help reduce morbidity and lower the financial implications for local NHS trusts.

Midterm Outcomes of a Synthetic Cartilage Implant for the First Metatarsophalangeal Joint in Advanced Hallux Rigidus.

BACKGROUND:: A prospective, randomized, noninferiority clinical trial of synthetic cartilage implant hemiarthroplasty for hallux rigidus demonstrated functional outcomes and safety equivalent to first metatarsophalangeal (MTP) joint arthrodesis at 24 months. We prospectively assessed safety and efficacy outcomes for synthetic cartilage implant hemiarthroplasty at a minimum of 5 years. METHODS:: Of 135 eligible patients from the original trial, 112 (83.0%) were enrolled (mean age, 58.2 ± 8.8 years; 87 females). Pain visual analog scale (VAS), Foot and Ankle Ability Measure (FAAM) Activities of Daily Living (ADL), and FAAM Sports subscales were completed preoperatively and 2 and 5 years postoperatively. Great toe active dorsiflexion, weightbearing radiographs, secondary procedures, and safety parameters were also evaluated. RESULTS:: At 24 months, 14/152 (9.2%) patients had undergone implant removal and conversion to arthrodesis. In years 2 to 5, 9/119 (7.6%) patients underwent implant removal and conversion to arthrodesis. At mean 5.8 ± 0.7 (range, 4.4-8.0) years' follow-up, pain VAS, FAAM ADL, and FAAM Sports scores improved by 57.9 ± 18.6 points, 33.0 ± 17.6 points, and 47.9 ± 27.1 points, respectively, from baseline. Clinically significant changes in VAS pain, FAAM ADL, and FAAM Sports were reported by 103/106 (97.2%), 95/105 (90.5%), and 97/104 (93.3%) patients, respectively. Patient-reported outcomes at 24 months were maintained at 5.8 years in patients who were not revised. Active MTP joint peak dorsiflexion was maintained. Ninety-nine of 106 (93.4%) patients would have the procedure again. CONCLUSION:: Clinical and safety outcomes for synthetic cartilage implant hemiarthroplasty observed at 2 years were maintained at 5.8 years. The implant remains a viable treatment option to decrease pain, improve function, and maintain motion for advanced hallux rigidus. LEVEL OF EVIDENCE:: Level IV, case series.

Wide-pulse, high-frequency, low-intensity neuromuscular electrical stimulation has potential for targeted strengthening of an intrinsic foot muscle: a feasibility study.

BACKGROUND: Strengthening the intrinsic foot muscles is a poorly understood and largely overlooked area. In this study, we explore the feasibility of strengthening m. abductor hallucis (AH) with a specific paradigm of neuromuscular electrical stimulation; one which is low-intensity in nature and designed to interleave physiologically-relevant low frequency stimulation with high-frequencies to enhance effective current delivery to spinal motoneurones, and enable a proportion of force produced by the target muscle to be generated from a central origin. We use standard neurophysiological measurements to evaluate the acute (~ 30 min) peripheral and central adaptations in healthy individuals. METHODS: The AH in the dominant foot of nine healthy participants was stimulated with 24 × 15 s trains of square wave (1 ms), constant current (150% of motor threshold), alternating (20 Hz-100 Hz) neuromuscular electrical stimulation interspersed with 45 s rest. Prior to the intervention, peripheral variables were evoked from the AH compound muscle action potential (Mwave) and corresponding twitch force in response to supramaximal (130%) medial plantar nerve stimulation. Central variables were evoked from the motor evoked potential (MEP) in response to suprathreshold (150%) transcranial magnetic stimulation of the motor cortex corresponding to the AH pathway. Follow-up testing occurred immediately, and 30 min after the intervention. In addition, the force-time-integrals (FTI) from the 1st and 24th WPHF trains were analysed as an index of muscle fatigue. All variables except FTI (T-test) were entered for statistical analysis using a single factor repeated measures ANOVA with alpha set at 0.05. RESULTS: FTI was significantly lower at the end of the electrical intervention compared to that evoked by the first train (p < 0.01). Only significant peripheral nervous system adaptations were observed, consistent with the onset of low-frequency fatigue in the muscle. In most of these variables, the effects persisted for 30 min after the intervention. CONCLUSIONS: An acute session of wide-pulse, high-frequency, low-intensity electrical stimulation delivered directly to abductor hallucis in healthy feet induces muscle fatigue via adaptations at the peripheral level of the neuromuscular system. Our findings would appear to represent the first step in muscle adaptation to training; therefore, there is potential for using WPHF for intrinsic foot muscle strengthening.

Treatment of first metatarsophalangeal joint arthritis using hemiarthroplasty with a synthetic cartilage implant or arthrodesis: A comparison of operative and recovery time.

BACKGROUND: First metatarsophalangeal joint (MTPJ1) hemiarthroplasty using a novel synthetic cartilage implant was as effective and safe as MTPJ1 arthrodesis in a randomized clinical trial. We retrospectively evaluated operative time and recovery period for implant hemiarthroplasty (n=152) and MTPJ1 arthrodesis (n=50). METHODS: Perioperative data were assessed for operative and anaesthesia times. Recovery and return to function were prospectively assessed with the Foot and Ankle Ability Measure (FAAM) Sports and Activities of Daily Living (ADL) subscales and SF-36 Physical Functioning (PF) subscore. RESULTS: Mean operative time for hemiarthroplasty was 35±12.3min and 58±21.5min for arthrodesis (p<0.001). Anaesthesia duration was 28min shorter with hemiarthroplasty (p<0.001). At weeks 2 and 6 postoperative, hemiarthroplasty patients demonstrated clinically and statistically significantly higher FAAM Sport, FAAM ADL, and SF-36 PF subscores versus arthrodesis patients. CONCLUSION: MTPJ1 hemiarthroplasty with a synthetic cartilage implant took less operative time and resulted in faster recovery than arthrodesis. LEVEL OF EVIDENCE: III, Retrospective case control study.

Cadaveric experiments to evaluate pressure wave generated by radial shockwave treatment of plantar fasciitis.

BACKGROUND: Shockwave treatment is increasingly used for plantar fasciitis and Achilles tendinopathy. To be effective it is believed that high pressure must be achieved in the tissues. We report on the first human cadaveric experiments to characterize pressure from radial shockwave therapy (rSWT) for plantar fasciitis. METHODS: The pressure from rSWT was measured in two cadaveric feet using a needle hydrophone. Maximal pressure and energy flux were calculated from the measurements. RESULTS: The pressure persisted longer than supposed, for up to 400µs. The peak negative pressure was up to two Mega Pascal. The predicted energy in the tissue strongly depended on the time interval used in calculations. CONCLUSIONS: The measured pressure may be sufficiently high to cause cavitation in the tissue, which is one of the proposed healing mechanisms associated with rSWT. The results suggest that the energy is imparted to the tissues for much longer than previously thought.

Correlation of Hallux Rigidus Grade With Motion, VAS Pain, Intraoperative Cartilage Loss, and Treatment Success for First MTP Joint Arthrodesis and Synthetic Cartilage Implant.

BACKGROUND: Grading systems are used to assess severity of any condition and as an aid in guiding treatment. This study examined the relationship of baseline motion, pain, and observed intraoperative cartilage loss with hallux rigidus grade. METHODS: A prospective, randomized study examining outcomes of arthrodesis compared to synthetic cartilage implant was performed. Patients underwent preoperative clinical examination, radiographic assessment, hallux rigidus grade assignment, and intraoperative assessment of cartilage loss. Visual analog scale (VAS) score for pain was obtained preoperatively and at 24 months. Correlation was made between active peak dorsiflexion, VAS pain, cartilage loss, and hallux rigidus grade. Fisher's exact test was used to assess grade impact on clinical success ( P < .05). RESULTS: In 202 patients, 59 (29%), 110 (55%), and 33 (16%) were classified as Coughlin grades 2, 3, and 4, respectively. There was no correlation between grade and active peak dorsiflexion (-0.069, P = .327) or VAS pain (-0.078, P = .271). Rank correlations between grade and cartilage loss were significant, but correlations were small. When stratified by grade, composite success rates between the 2 treatments were nearly identical. CONCLUSIONS: Irrespective of the grade, positive outcomes were demonstrated for both fusion and synthetic cartilage implant. Clinical symptoms and signs should be used to guide treatment, rather than a grade consisting of radiographic, symptoms, and range of motion factors. LEVEL OF EVIDENCE: Level II, randomized clinical trial.

Association Between Patient Factors and Outcome of Synthetic Cartilage Implant Hemiarthroplasty vs First Metatarsophalangeal Joint Arthrodesis in Advanced Hallux Rigidus.

BACKGROUND: We evaluated data from a clinical trial of first metatarsophalangeal joint (MTPJ1) implant hemiarthroplasty and arthrodesis to determine the association between patient factors and clinical outcomes. METHODS: Patients ≥18 years with hallux rigidus grade 2, 3, or 4 were treated with synthetic cartilage implant MTPJ1 hemiarthroplasty or arthrodesis. Pain visual analog scale (VAS), Foot and Ankle Ability Measure (FAAM) sports and activities of daily living (ADL) scores, and Short Form-36 Physical Function (SF-36 PF) subscore were obtained preoperatively, and at 2, 6, 12, 24, 52, and 104 weeks postoperatively. Final outcome data, great toe active dorsiflexion motion, secondary procedures, radiographs, and safety parameters were evaluated for 129 implant hemiarthroplasties and 47 arthrodeses. The composite primary endpoint criteria for clinical success included VAS pain reduction ≥30%, maintenance/improvement in function, no radiographic complications, and no secondary surgical intervention at 24 months. Predictor variables included hallux rigidus grade; gender; age; body mass index (BMI); symptom duration; prior MTPJ1 surgery; preoperative hallux valgus angle, range of motion (ROM), and pain. Two-sided Fisher exact test was used ( P < .05). RESULTS: Patient demographics and baseline outcome measures were similar. Success rates between implant MTPJ1 hemiarthroplasty and arthrodesis were similar ( P > .05) when stratified by hallux rigidus grade, gender, age, BMI, symptom duration, prior MTPJ1 surgery status, and preoperative VAS pain, hallux valgus, and ROM. CONCLUSION: Synthetic cartilage implant hemiarthroplasty was appropriate for patients with grade 2, 3, or 4 hallux rigidus. Its results in those with associated mild hallux valgus (≤20 degrees) or substantial preoperative stiffness were equivalent to MTPJ1 fusion, irrespective of gender, age, BMI, hallux rigidus grade, preoperative pain or symptom duration. LEVEL OF EVIDENCE: Level II, randomized clinical trial.

Syndesmosis Stabilisation: Screws Versus Flexible Fixation.

Orthopedic surgery is not short of situations where there is controversy regarding optimum management. Treating ankle syndesmosis injuries is an example where practice varies widely and there are many questions that remain unsatisfactorily answered. When addressing the type of syndesmosis stabilization that is required it is essential to ascertain the extent of instability. Only then can a logical approach to restoring the ankle mortise be achieved. Fixation of fibula shaft fractures and posterior malleolus fractures can restore sufficient stability to render syndesmosis stabilization unnecessary. The indications and techniques for stabilizing the distal tibiofibular joint are reviewed with clinical examples.

Prospective, Randomized, Multi-centered Clinical Trial Assessing Safety and Efficacy of a Synthetic Cartilage Implant Versus First Metatarsophalangeal Arthrodesis in Advanced Hallux Rigidus.

BACKGROUND: Although a variety of great toe implants have been tried in an attempt to maintain toe motion, the majority have failed with loosening, malalignment/dislocation, implant fragmentation and bone loss. In these cases, salvage to arthrodesis is more complicated and results in shortening of the ray or requires structural bone graft to reestablish length. This prospective study compared the efficacy and safety of this small (8/10 mm) hydrogel implant to the gold standard of a great toe arthrodesis for advanced-stage hallux rigidus. METHODS: In this prospective, randomized non-inferiority study, patients from 12 centers in Canada and the United Kingdom were randomized (2:1) to a synthetic cartilage implant or first metatarsophalangeal (MTP) joint arthrodesis. VAS pain scale, validated outcome measures (Foot and Ankle Ability Measure [FAAM] sport scale), great toe active dorsiflexion motion, secondary procedures, radiographic assessment, and safety parameters were evaluated. Analysis was performed using intent-to-treat (ITT) and modified ITT (mITT) methodology. The primary endpoint for the study consisted of a single composite endpoint using the 3 primary study outcomes (pain, function, and safety). The individual subject's outcome was considered a success if all of the following criteria were met: (1) improvement (decrease) from baseline in VAS pain of ≥30% at 12 months; (2) maintenance of function from baseline in FAAM sports subscore at 12 months; and (3) absence of major safety events at 2 years. The proportion of successes in each group was determined and 1-sided 95% confidence interval for the difference between treatment groups was calculated. Noninferiority of the implant to arthrodesis was considered statistically significant if the 1-sided 95% lower confidence interval was greater than the equivalence limit (<15%). A total of 236 patients were initially enrolled; 17 patients withdrew prior to randomization, 17 patients withdrew after randomization, and 22 were nonrandomized training patients, leaving 152 implant and 50 arthrodesis patients. Standard demographics and baseline outcomes were similar for both groups. RESULTS: VAS pain scores decreased significantly in both the implant and arthrodesis groups from baseline at 12 and 24 months. Similarly, the FAAM sports and activity of daily living subscores improved significantly at 12 and 24 months in both groups. First MTP active dorsiflexion motion improvement was 6.2 degrees (27.3%) after implant placement and was maintained at 24 months. Subsequent secondary surgeries occurred in 17 (11.2%) implant patients (17 procedures) and 6 (12.0%) arthrodesis patients (7 procedures). Fourteen (9.2%) implants were removed and converted to arthrodesis, and 6 (12.0%) arthrodesis patients (7 procedures [14%]) had isolated screws or plate and screw removal. There were no cases of implant fragmentation, wear, or bone loss. When analyzing the ITT and mITT population for the primary composite outcome of VAS pain, function (FAAM sports), and safety, there was statistical equivalence between the implant and arthrodesis groups. CONCLUSION: A prospective, randomized (2:1), controlled, noninferiority clinical trial was performed to compare the safety and efficacy of a small synthetic cartilage bone implant to first MTP arthrodesis in patients with advanced-stage hallux rigidus. This study showed equivalent pain relief and functional outcomes. The synthetic implant was an excellent alternative to arthrodesis in patients who wished to maintain first MTP motion. The percentage of secondary surgical procedures was similar between groups. Less than 10% of the implant group required revision to arthrodesis at 2 years. LEVEL OF EVIDENCE: Level I, prospective randomized study.

Finite element modelling of radial shock wave therapy for chronic plantar fasciitis.

Therapeutic use of high-amplitude pressure waves, or shock wave therapy (SWT), is emerging as a popular method for treating musculoskeletal disorders. However, the mechanism(s) through which this technique promotes healing are unclear. Finite element models of a shock wave source and the foot were constructed to gain a better understanding of the mechanical stimuli that SWT produces in the context of plantar fasciitis treatment. The model of the shock wave source was based on the geometry of an actual radial shock wave device, in which pressure waves are generated through the collision of two metallic objects: a projectile and an applicator. The foot model was based on the geometry reconstructed from magnetic resonance images of a volunteer and it comprised bones, cartilage, soft tissue, plantar fascia, and Achilles tendon. Dynamic simulations were conducted of a single and of two successive shock wave pulses administered to the foot. The collision between the projectile and the applicator resulted in a stress wave in the applicator. This wave was transmitted into the soft tissue in the form of compression-rarefaction pressure waves with an amplitude of the order of several MPa. The negative pressure at the plantar fascia reached values of over 1.5 MPa, which could be sufficient to generate cavitation in the tissue. The results also show that multiple shock wave pulses may have a cumulative effect in terms of strain energy accumulation in the foot.

Gastrocnemius shortening and heel pain.

Pain and reduced function caused by disorders of either the plantar fascia or the Achilles tendon are common. Although heel pain is not a major public health problem it affects millions of people each year. For most patients, time and first-line treatments allow symptoms to resolve. A proportion of patients have resistant symptoms. Managing these recalcitrant cases is a challenge. Gastrocnemius contracture produces increased strain in both the Achilles tendon and the plantar fascia. This biomechanical feature must be properly assessed otherwise treatment is compromised.

Posterior ankle and hind foot arthroscopy - how do you responsibly learn this new technique?

Posterior ankle and hind foot arthroscopy has become an important diagnostic and therapeutic tool when dealing with ankle pathology. Although not yet widely adopted it is gaining popularity and there have been various descriptions of the technique [1] and its outcomes [2,3]. With posterior arthroscopy there are well-documented risks of injury to the sural nerve and medial neurovascular bundle in particular [7-9]. These risks need to be carefully considered, particularly by surgeons early in the learning curve of what is undoubtedly a challenging technique. In an ideal world there should be scope for regular simulation to be integrated into a consultant's working week and this would allow them to be prepared for untoward incidences and also learn new techniques such as hind-foot arthroscopy in a safe environment prior to introduction into clinical practice.

Nonunion of fifth metatarsal fractures.

Metatarsal fractures are those most frequently encountered in the foot. More than half of these are of the 5th metatarsal. The incidence is increasing, along with the activity levels of the general population. Fractures of the 5th metatarsal require careful evaluation and classification to ensure selection of the optimum treatment plan. Distal fractures rarely require fixation, even when displacement is wide. Cases of established nonunion or refracture require fixation.