Ruben Radkievich

Biomechanical Evaluation of Circumtibial and Transmembranous Routes for Posterior Tibial Tendon Transfer for Dropfoot

Background: Tibialis posterior tendon transfer is performed when loss of dorsiflexion has to be compensated. We evaluated the circumtibial (CT), above-retinaculum transmembranous (TMAR), and under-retinaculum transmembranous (TMUR) transfer gliding resistance and foot kinematics in a cadaveric foot model during ankle range of motion (ROM). Methods: Eight cadaveric foot-ankle distal tibia specimens were dissected free of soft tissues on the proximal end, applying an equivalent force to 50% of the stance phase to every tendon, except for the Achilles tendon. Dorsiflexion was tested with all of the tibialis posterior tendon transfer methods (CT, TMAR, and TMUR) using a tension tensile machine. A 10-repetition cycle of dorsiflexion and plantarflexion was performed for each transfer. Foot motion and the force needed to achieve dorsiflexion were recorded. Results: The CT transfer showed the highest gliding resistance (P < .01). Regarding kinematics, all transfers decreased ankle ROM, with the CT transfer being the condition with less dorsiflexion compared with the control group (6.8 vs 15 degrees, P < .05). TMUR transfer did perform better than TMAR with regard to ankle dorsiflexion, but no difference was shown in gliding resistance. The CT produced a supination moment on the forefoot. Conclusion: The CT transfer had the highest tendon gliding resistance, achieved less dorsiflexion and had a supination moment. Clinical Relevance We suggest that the transmembranous tibialis posterior tendon transfer should be the transfer of choice. The potential bowstringing effect when performing a tibialis posterior tendon transfer subcutaneously (TMAR) could be avoided if the transfer is routed under the retinaculum, without significant compromise of the final function and even with a possible better ankle range of motion.

Biomechanical Cadaveric Evaluation of Partial Acute Peroneal Tendon Tears

Background: No clear guideline or solid evidence exists for peroneal tendon tears to determine when to repair, resect, or perform a tenodesis on the damaged tendon. The objective of this study was to analyze the mechanical behavior of cadaveric peroneal tendons artificially damaged and tested in a cyclic and failure mode. The hypothesis was that no failure would be observed in the cyclic phase. Methods: Eight cadaveric long leg specimens were tested on a specially designed frame. A longitudinal full thickness tendon defect was created, 3 cm in length, behind the tip of the fibula, compromising 66% of the visible width of the peroneal tendons. Cyclic testing was initially performed between 50 and 200 N, followed by a load-to-failure test. Tendon elongation and load to rupture were measured. Results: No tendon failed or lengthened during cyclic testing. The mean load to failure for peroneus brevis was 416 N (95% confidence interval, 351–481 N) and for the peroneus longus was 723 N (95% confidence interval, 578–868 N). All failures were at the level of the defect created. Conclusion: In a cadaveric model of peroneal tendon tears, 33% of remaining peroneal tendon could resist high tensile forces, above the physiologic threshold. Clinical Relevance: Some peroneal tendon tears can be treated conservatively without risking spontaneous ruptures. When surgically treating a symptomatic peroneal tendon tear, increased efforts may be undertaken to repair tears previously considered irreparable.

Proximal Rotational Metatarsal Osteotomy for Hallux Valgus: Technique Description and Prospective Case Series

Category: Bunion, Midfoot/Forefoot Introduction/Purpose: Hallux valgus combines two deformities, the metatarsus varus and metatarsal internal rotation. The rotational deformity is seldom corrected during surgery, but is a known recurrence factor. Most techniques only correct the metatarsus varus (scarf, chevron, etc). We present a prospective case series using a novel metatarsal rotational osteotomy called PROMO (proximal rotational metatarsal osteotomy) which simultaneously corrects the metatarsal internal rotation and varus deformity by rotating the metatarsal through an oblique plane osteotomy. This is performed with no bone resection. Our objective was to report this new technique, preliminary results, its advantages and complications. Methods: 20 consecutive patients (17 women) with Hallux Valgus, average age 45 (25-55), were operated using this technique. The average preoperative intermetatarsal angle (IMA) was 15 degrees with an average Hallux internal malrotation of 30 degrees and a sesamoid malposition of grade V or more in all cases. Postoperatively, sesamoids position, Hallux rotation, IMA and metatarsal length were registered. They were followed for 1 year (8-14 months). The surgical technique is described, with its potential benefits and drawbacks. The radiological outcome, postoperative LEFS score, recurrence rate (IMA increase >5 degrees) and complications were registered. Results: Well positioned sesamoids (grade IV or less) were obtained in all patients postoperatively, with a complete Hallux rotational correction. Postoperative IMA was 5 degrees. achieving a complete metatarsal varus correction. No metatarsal shortening was observed whatsoever. No recurrence has been observed until final follow up. Preoperative and postoperative LEFS scores were 58 and 73 respectively. Conclusion: The PROMO has the advantage over other osteotomies that it can reliable correct, both metatarsal malrotation and varus deformities, achieving a complete deformity correction and hopefully decreasing recurrence rate. The surgical technique has been studied and refined extensively, in order to simplify it and make it reliable. Although more patients and follow-up are needed, the authors believe it is a promising surgical technique which addresses a previously not considered hallux valgus deformity component.

Early Weight Bearing on Weber C Fractures with Retained Syndesmotic Screws

Category: Ankle, Sports, Trauma Introduction/Purpose: There is no consensus about when to allow weight bearing in ankle fractures treated with syndesmotic screw fixation. There has been no evaluation of the radiographic fate of the syndesmosis when syndesmotic screws are retained and early weight bearing is encouraged, or the clinical result depending on the screw status, which can be intact, broken or loose. Our objective was to evaluate the radiographic and clinical parameters of patients who had a screw fixation of the syndesmosis and early weight bearing was allowed. Our hypothesis was that no difference would be observed on syndesmotic reduction or clinical function depending on the screw status. Methods: We analyzed 42 patients with ankle fractures treated with syndesmotic screws in which early weight bearing was allowed (3 weeks postoperatively). Weight bearing radiographs were obtained at 2 weeks, 2 months and at final follow up (41.2 months). Radiologically we measured medial clear space (MCS), tibiofibular overlap (OL), tibiofibular clear space (CS), talar shift (TS) and screw condition (intact, broken, loose). Clinical function was measured with the AOFAS score and stratified by the screw condition. Statistical analysis was performed with the SPSS software and a non-inferiority confidence interval for the mean was calculated. Results: At final follow up, 66,6% of the screws were broken, 30,9% showed significant loosening and only 1 patient (4,7%) had a screw that remained solid with no signs of osteolysis. MCS at 2 weeks, 2 months and at final follow up was 2,94 mm; 3,03 mm; 3,02, respectively. OL was 6,76 mm; 6,78 mm; 6,83 and CS was 4,26 mm; 4,66 mm; 4,6 mm. No TS was detected. There was no difference in measurements along time (p>0,05). Relative to clinical function, the mean AOFAS score was 95 points. No difference was found between the clinical scores of patients stratified by the screw condition (p>0,05). Conclusion: Early weight bearing on a fixed syndesmosis appears to be safe, with no measurable radiographic or clinical consequences regarding ankle joint function. Despite screw breakage or loosening on x-rays, loss of reduction is seldom observed. We suggest that routine removal of syndesmotic screws is not necessary in these group of patients.

Posterior tibial tendon transfer: Biomechanical evaluation of circumtibial, above-retinaculum and below-retinaculum transmembranous transfer

Category: Ankle, Basic Sciences/Biologics, Tendon Transfer, Dropfoot Introduction/Purpose: Posterior tibial tendon transfer (PTTT) is performed for a variety of pathologies where loss of dorsiflexion is compensated by the transfer, e.g. cavus foot, neurologic foot (dropfoot), etc. Transfers can be performed subcutaneously through a circumtibial way or deeply through the interosseous membrane (transmembranous). The latter is classically routed above the extensor retinaculum. We evaluated the circumtibial (CT), above-retinaculum transmembranous (ART) and below-retinaculum transmembranous (BRT) transfers gliding resistance and kinematics in a cadaveric model during ankle range of motion (ROM). Our first hypothesis was that the CT would be the transfer with more gliding resistance and with more kinematic alteration. Our second hypothesis was that the ART would not show significant differences against the BRT transfer. Methods: 8 cadaveric foot- ankle – distal tibia were prepared, identifying all extensor and flexor tendons proximally. The skin and subcutaneous tissue were kept intact. Each specimen was mounted on a special frame, and luminous markers were attached to the skin to adapt it to the Oxford Foot Model. A dead weight equal to 50% of the stance phase force was applied to each tendon, except for the Achilles tendon. Each specimen served as its own control, testing dorsiflexion when pulling the tibialis anterior (TA), recording the kinematics and gliding resistance. Then, dorsiflexion was tested with the transfers already described (CT, ART and BRT PTTT). A 10-repetition cycle of dorsiflexion and plantarflexion was performed for each condition. The movement of the foot was recorded using high speed cameras, and the force needed to achieve dorsiflexion was registered in every cycle. Statistical analysis was performed using the SPSS software. Results: The circumtibial transfer showed the highest gliding resistance (p<0.05). The ART and BRT transfers increased the least the gliding resistance over the control, with no difference between them (p>0.05). Regarding kinematics, all transfers decreased ankle ROM, being the CT transfer the condition with less range of motion (-9 degrees, p<0.05). ART and BRT transfers did not show differences relative to ankle ROM among them. The CT transfer significantly produced more supination of the forefoot over the hindfoot (p<0.05). The ART and BRT transfers did not differ from the control group relative to supination/pronation. Finally all the transfers produced a significant abduction motion of the forefoot compared to the control, with no difference between them. Conclusion: The circumtibial transfer had the highest tendon gliding resistance and the worst kinematics of all transfers. It achieves less dorsiflexion and in an inverted position. Interestingly, there was minimal difference in gliding resistance between the above and below retinaculum transmembranous transfers. Per our results, we suggest that when performing a PTTT the transmembranous route should be the transfer of choice. The potential bowstringing effect which may be painful and not cosmetic for patients when performing a PTTT subcutaneously (ART) could be avoided if the transfer is routed under the retinaculum, without significant compromise of the final function.