Tanawat Vaseenon

Forceps Reduction of the Syndesmosis in Rotational Ankle Fractures A Cadaveric Study

BACKGROUND Recent studies have shown that it is difficult to accurately reduce and assess the reduction of the syndesmosis after ankle injury. The syndesmosis is most commonly reduced with use of reduction clamps to compress across the tibia and fibula. However, intraoperative techniques to optimize forceps reductions to restore syndesmotic relationships accurately have not been systematically studied. The purpose of the present study was to evaluate the accuracy of syndesmosis reduction with different rotational vectors of clamp placement. METHODS Ten through-the-knee cadaveric specimens were used. Markers were placed on the tibia and fibula to produce consistent clamp placement and radiographic evaluation. A computed tomographic scan of the ankle was made to serve as a control, followed by a stepwise destabilization of the anterior inferior tibiofibular ligament, syndesmosis, deltoid ligament, small posterior malleolus fracture, and large posterior malleolus fracture. Following each step in the destabilization, clamps were applied to compress the syndesmosis at varying angles and computed tomography was performed to measure the alignment of the syndesmosis as compared with that on the control scan. RESULTS In all degrees of induced instability, and for all vectors of clamp placement, a small but consistent amount of overcompression of the syndesmosis was observed. The average overcompression (and standard deviation) for all samples was 0.93 ± 0.70 mm. Both obliquely oriented clamp arrangements consistently caused fibular malreductions in the sagittal plane. Placing the clamp in the neutral anatomical axis reduced the syndesmosis most accurately, with an average displacement of 0.1 ± 0.77 mm compared with control through all degrees of instability. CONCLUSIONS Clamp placement in the neutral anatomical axis reduced the syndesmosis most accurately in our cadaveric model, although slight overcompression was frequently observed. Placing the clamp obliquely malreduced the unstable syndesmosis.

Instability Dependency of Osteoarthritis Development in a Rabbit Model of Graded Anterior Cruciate Ligament Transection

BACKGROUND Joint instability has long been empirically recognized as a leading risk factor for osteoarthritis. However, formal mechanistic linkage of instability to osteoarthritis development has not been established. This study aimed to support a clinically accepted, but heretofore scientifically unproven, concept that the severity and rapidity of osteoarthritis development in unstable joints is dependent on the degree of instability. In a survival rabbit knee model of graded joint instability, the relationship between the magnitude of instability and the intensity of cartilage degeneration was studied at the organ level in vivo. METHODS Sixty New Zealand White rabbits received either complete or partial (medial half) transection of the anterior cruciate ligament or sham surgery (control) on the left knee. At the time that the animals were killed at eight or sixteen weeks postoperatively (ten animals for each treatment and/or test-period combination), the experimental knees were subjected to sagittal plane stability measurement, followed by whole-joint cartilage histological evaluation with use of the Mankin score. RESULTS Sagittal plane instability created in the partial transection group was intermediate between those in the complete transection and sham surgery groups. The partial and complete transection groups exhibited cartilage degeneration on the medial femoral and/or medial tibial surfaces. The average histological score (and standard deviation) for the medial compartment in the partial transection group (2.9 ± 0.9) was again intermediate, significantly higher than for the sham surgery group (1.9 ± 0.8) and significantly lower than for the complete transection group (4.5 ± 2.3). The average histological scores for the medial compartment in the partial transection group correlated significantly with the magnitude of instability, with no threshold effect being evident. The significance level of alpha was set at 0.05 for all tests. CONCLUSIONS The severity of cartilage degeneration increased continuously with the degree of instability in this survival rabbit knee model of graded instability.

Entropy analysis of tri-axial leg acceleration signal waveforms for measurement of decrease of physiological variability in human gait.

Disease‐related and senescent decrease of physiological variability in biological time‐series outputs (e.g., heart rate) has drawn increasing attention as a potential new type of biomarker. In this paradigm, measurement of variability in periodic motion may enable quantitative evaluation of functional limitation in people with musculoskeletal disorders. A novel technique to measure variability of leg motion patterns during level walking was used to study 52 adults with symptomatic knee osteoarthritis (OA), and 57 asymptomatic control subjects over a wide range of age (20–79 years). The hypothesis was that cycle‐to‐cycle variability in leg motion patterns, indexed by tri‐axial acceleration signal entropy, would be lower in those with greater age or with knee symptoms. Leg motions were assessed using portable inertial monitors attached bilaterally just above each ankle. The tri‐axial acceleration data were analyzed using a nonlinear variability measurement tool designated as Sample Entropy (SampEn). SampEn data for asymptomatic subjects exhibited a significant negative correlation (r = −0.287, p = 0.0306) with greater age. OA subjects had significantly lower SampEn values (p = 0.0002) than did age‐matched asymptomatic subjects who walked at equivalent velocity. This approach holds promise as a basis for valid, inexpensive, and convenient objective evaluation of limitations in human gait function.

Effect of Implantation Accuracy on Ankle Contact Mechanics with a Metallic Focal Resurfacing Implant

BACKGROUND Talar osteochondral defects can lead to joint degeneration. Focal resurfacing with a metallic implant has shown promise in other joints. We studied the effect of implantation accuracy on ankle contact mechanics after focal resurfacing of a defect in the talar dome. METHODS Static loading of seven cadaver ankles was performed before and after creation of a 15-mm-diameter osteochondral defect on the talar dome, and joint contact stresses were measured. The defect was then resurfaced with a metallic implant, with use of a custom implant-bone interface fixture that allowed fine control (in 0.25-mm steps) of implantation height. Stress measurements were repeated at heights of -0.5 to +0.5 mm relative to an as-implanted reference. Finite element analysis was used to determine the effect of implant height, post axis rotation, and valgus/varus tilt over a motion duty cycle. RESULTS With the untreated defect, there was a 20% reduction in contact area and a 40% increase in peak contact stress, as well as a shift in the location of the most highly loaded region, as compared with the values in the intact condition. Resurfacing led to recovery of 90% of the contact area that had been measured in the intact specimen, but the peak contact stresses remained elevated. With the implant 0.25 mm proud, peak contact stress was 220% of that in the intact specimen. The results of the finite element analyses agreed closely with those of the experiments and additionally showed substantial variations in defect influences on contact stresses across the motion arc. Talar internal/external rotations also differed for the unfilled defect. Focal implant resurfacing substantially restored kinematics but did not restore the stresses to the levels in the intact specimens. CONCLUSIONS Focal resurfacing with a metallic implant appears to have the potential to restore normal joint mechanics in ankles with a large talar osteochondral defect. However, contact stresses were found to be highly sensitive to implant positioning.

Update on anterior ankle impingement

Anterior ankle impingement results from an impingement of the ankle joint by a soft tissue or osteophyte formation at the anterior aspect of the distal tibia and talar neck. It often occurs secondary to direct trauma (impaction force) or repetitive ankle dorsiflexion (repetitive impaction and traction force). Chronic ankle pain, swelling, and limitation of ankle dorsiflexion are common complaints. Imaging is valuable for diagnosis of the bony impingement but not for the soft tissue impingement, which is based on clinical findings. MR imaging and MR arthrography are helpful in doubtful diagnoses and the identification of associated injuries. Recommended methods for initial management include rest, physical therapy, and shoe modification. If nonoperative treatment fails, arthroscopic bony or soft tissue debridement both offer significant symptomatic relief with long-term positive outcomes in cases that have no significant arthritic change, associated ligament laxity, and chondral lesion.

Long-term mortality after osteoporotic hip fracture in Chiang Mai, Thailand.

The purpose of the study was to investigate 10-yr mortality and associated factors after osteoporotic hip fracture. A prospective cohort study of mortality and associated factors was carried out in patients who sustained hip fracture and were admitted to Chiang Mai University Hospital from 1998 through 2003. Eligibility criteria were defined as age over 50yr, hip fracture caused by simple fall, and Singh index of 3 or less.Mortality rates at 3, 6, 12, 24, 36, 60, 96, and 120mo were 10%, 14%, 18%, 27%, 32%, 45%, 55%, and 68%, respectively. One-year mortality rates were 31% in males and 16% in females. The median survival time was 6yr. Ten-year mortality was 68%. Factors correlated with higher mortality were male gender, age greater than 70yr, and nonoperative treatment. Mortality after osteoporotic hip fracture in Thais was extremely high, especially in the first year. It was about 8 times higher than that in the age-adjusted general population.

Vascular Disruption of the Talus Comparison of Two Approaches for Triple Arthrodesis

Background: For triple arthrodesis, a single medial incision has been proposed to avoid lateral wound complications and has demonstrated satisfactory fusion rates. This study aimed to compare the disruption to the arterial supply of the talus between the single-medial-incision approach and the 2-incision approach. Methods: The 2 approaches for triple arthrodesis were compared by analyzing the disruption of arterial vasculature in 14 cadaveric specimens in randomized fashion. The arterial disruption was determined using CT angiography before and after surgery combined with analysis from dissection. The area of joint preparation from each technique was also analyzed and compared. Results: The single-medial-incision approach caused a high incidence of damage to the deltoid artery (6 of 7 specimens, 86%) and the artery of the tarsal canal (7 of 7 specimens, 100%). The 2-incision approach resulted in damage to the artery of the tarsal sinus in all specimens (7 of 7 specimens, 100%), but the medial vasculature was spared given the limited dissection required to access the talonavicular joint. Through the single-medial-incision approach the percentage of debridement of the calcaneocuboid joint (36%) was significantly lower than the debridement using the 2-incision approach (85%, P < .01). There was no significant difference in joint preparation of the talonavicular and subtalar joints between the 2 approaches with the number of specimens available. Conclusion: From this cadaveric study, we found that both approaches could result in substantial disruption of the main blood supply to the talus. The single-medial-incision approach consistently disrupted the majority of blood supply to the talar body, while the 2-incision approach caused various degrees of vascular disruption to the talar head and neck. Using the single-medial-incision approach, the calcaneocuboid joint did not show adequate removal of articular cartilage due to difficulty accessing the joint surfaces. Clinical Relevance: Vascular sparing to the talus should be considered when selecting an appropriate operative approach for triple arthrodesis. Although the clinical significance of this cadaveric study is limited, the 2-incision approach appeared to cause less vascular disruption to the talar body while allowing more complete joint preparation.

Minimally invasive plate osteosynthesis of distal tibial fracture using a posterolateral approach: a cadaveric study and preliminary report

PurposeThe aims of this anatomical study were to evaluate the feasibility of minimally invasive plate osteosynthesis (MIPO) using a posterolateral approach in distal tibial fractures and to study the relationship between neurovascular structures and the plate.MethodsTwo separate incisions, one proximal and one distal, were made on the posterolateral aspect of ten cadaveric legs in the prone position. A 14-hole contralateral anterolateral distal tibial locking plate was inserted into the submuscular tunnel using a posterolateral approach, and one screw was fixed on each side of the proximal and distal tibia. The MIPO tunnel was then explored to identify the relationship between neurovascular bundles and plate.ResultsFor the proximal incision, retraction of the flexor hallucis longus and the tibialis posterior muscles medially was very important because it could protect the posterior tibial artery and the tibial nerve during plating. The sural nerve and lesser saphenous vein were easily identified and retracted in the superficial layer of the distal incision. In addition, we achieved satisfactory outcomes after using this MIPO technique in one patient.ConclusionBased on the results of our study, it seems that using the MIPO technique through a posterolateral approach should be a reasonable and safe treatment option for distal tibial fractures, especially when the anterior soft tissue is compromised. However, studies with a higher level of evidence should be done in more patients to confirm the clinical safety of using this technique.

Organ-Level Histological and Biomechanical Responses from Localized Osteoarticular Injury in the Rabbit Knee

The processes of whole‐joint osteoarthritis development following localized joint injuries are not well understood. To demonstrate this local‐to‐global linkage, we hypothesized that a localized osteoarticular injury in the rabbit knee would not only cause biomechanical and histological abnormalities in the involved compartment but also concurrent histological changes in the noninvolved compartment. Twenty rabbits had an acute osteoarticular injury that involved localized joint incongruity (a 2‐mm osteochondral defect created in the weight‐bearing area of the medial femoral condyle), while another 20 received control sham surgery. At the time of euthanasia at 8 or 16 weeks post‐surgery, the experimental knees were subjected to sagittal‐plane laxity measurement, followed by cartilage histo‐morphological evaluation using the Mankin score. The immediate effects of defect creation on joint stability and contact mechanics were explored in concomitant rabbit cadaver experimentation. The injured animals had cartilage histological scores significantly higher than in the sham surgery group (p < 0.01) on the medial femoral, medial tibial, and lateral femoral surfaces (predominantly on the medial surfaces), accompanied by slight (mean 20%) increase of sagittal‐plane laxity. Immediate injury‐associated alterations in the medial compartment contact mechanics were also demonstrated. Localized osteoarticular injury in this survival animal model resulted in global joint histological changes.

Arthroscopic Debridement for First Metatarsophalangeal Joint Arthrodesis With a 2- Versus 3-Portal Technique: A Cadaveric Study

PURPOSE To evaluate the safety and efficacy of arthroscopic debridement for arthrodesis of the first metatarsophalangeal (MTP) joint using a 2-portal technique versus a 3-portal technique. METHODS Twelve cadavers, with a mean age of 60 years, were subjected to arthroscopic debridement of the first MTP joint. Dorsolateral and dorsomedial portals were used in 6 specimens, whereas a medial portal was added in the other 6 specimens. The articular cartilage was debrided on both the proximal and distal surfaces and stabilized with a K-wire. The surrounding neurovascular structures were evaluated for injuries and measured for the distance from the portals. The fusion contact areas were estimated and denuded surfaces were measured on both sides. Results between the 2- and 3-portal techniques were compared. Statistical significance was taken as P < .05. RESULTS The mean estimated fusion contact area was 180.19 mm(2) on the proximal phalanx and 180.21 mm(2) on the distal metatarsal articular surfaces. On the proximal phalanx, the percentage of denuded area was 94.71% with the 2-portal technique and 97.60% with the 3-portal technique. On the distal metatarsal, the percentage of denuded area was 93.31% with the 2-portal technique and 95.22% with the 3-portal technique. The 3-portal technique statistically increased the area of debridement on the plantar-medial surface of the distal metatarsal. The mean distance from the dorsolateral portal to the dorsolateral hallucal nerve was 3.4 mm. The mean distance from the dorsomedial portal to the dorsomedial hallucal nerve was 4 mm. The medial portal was, on average, 10.5 mm from the dorsomedial hallucal nerve and 13 mm from the plantar-medial hallucal nerve. There was no visible nerve injury detected. CONCLUSIONS The 3-portal technique for arthroscopic-assisted arthrodesis of the first MTP joint allowed more complete cartilage debridement when compared with the 2-portal technique. The additional medial portal was found to be safe from the surrounding neurovascular structures. CLINICAL RELEVANCE Joint preparation for arthroscopic assisted arthrodesis of the first MTP joint can be safely and effectively performed using 3-portal technique, which may reduce the risk of non-union.