Da-wei Chen

Anatomy and biomechanical properties of the plantar aponeurosis: a cadaveric study.

Objectives To explore the anatomy of the plantar aponeurosis (PA) and its biomechanical effects on the first metatarsophalangeal (MTP) joint and foot arch. Methods Anatomic parameters (length, width and thickness of each central PA bundle and the main body of the central part) were measured in 8 cadaveric specimens. The ratios of the length and width of each bundle to the length and width of the central part were used to describe these bundles. Six cadaveric specimens were used to measure the range of motion of the first MTP joint before and after releasing the first bundle of the PA. Another 6 specimens were used to evaluate simulated static weight-bearing. Changes in foot arch height and plantar pressure were measured before and after dividing the first bundle. Results The average width and thickness of the origin of the central part at the calcaneal tubercle were 15.45 mm and 2.79 mm respectively. The ratio of the length of each bundle to the length of the central part was (from medial to lateral) 0.29, 0.30, 0.28, 0.25, and 0.27, respectively. Similarly, the ratio of the widths was 0.26, 0.25, 0.23, 0.19 and 0.17. The thickness of each bundle at the bifurcation of the PA into bundles was (from medial to lateral) 1.26 mm, 1.04 mm, 0.91 mm, 0.84 mm and 0.72 mm. The average dorsiflexion of the first MTP joint increased 10.16° after the first bundle was divided. Marked acute changes in the foot arch height and the plantar pressure were not observed after division. Conclusions The first PA bundle was not the longest, widest, or the thickest bundle. Releasing the first bundle increased the range of motion of the first MTP joint, but did not acutely change foot arch height or plantar pressure during static load testing.

Open reduction and internal fixation of posterior pilon fractures with buttress plate

Objective: Posterior pilon fractures are rare injuries and have not yet gained well recognition. The purpose of this study was to present the treatment outcome for patients with posterior pilon fractures treated with buttress plate. Method: In this retrospective study we identified patients with posterior pilon fractures of the distal tibia who had undergone open reduction and internal fixation at our institute. Between January 2007 and December 2009, 10 patients (mean age, 46.5 years) who had undergone buttress plating via either a posterolateral approach or a dual posterolateral-posteromedial approach, were selected. All 10 patients were available for follow-up. The clinical outcome was evaluated with the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and the visual analogue scale (VAS). The radiological evaluation was performed using the osteoarthritis-score (OA-score). Results: Satisfactory reduction and stable fixation were accomplished in all patients. At a mean follow-up of 36.2 months, all patients had good radiological results and showed satisfactory clinical recovery. The mean AOFAS sore was 87.8, the mean OA-score was 0.6, and the mean VAS scores during rest, active motion, and weight-bearing walking were 0.6, 0.8, and 1.4, respectively. Conclusion: Buttress plating for posterior pilon fractures gave satisfactory clinical outcomes. It also ensured rigid fixation which in turn enabled earlier postoperative mobilization. Level of Evidence IV, Retrospective Study.

Surgical Management for Avulsion Fracture of the Calcaneal Tuberosity

To discuss the operative methods and curative effect of calcaneal tuberosity fracture.

Torsional stiffness in supplemental one-third tubular plate fixation for isolated syndesmosis injuries.

Dear Editor: We read with great interest your recent publication of the article by Dr Clanton et al. In their biomechanical study, they compared the torsional stiffness about the ankle with and without the supplementary one-third tubular plate fixation after the syndesmotic screw was removed. They concluded that the use of supplementary one-third tubular plate fixation demonstrated a trend toward increasing the torsional stiffness following syndesmotic screw removal. This is an interesting study. However, there are some concerns regarding the study. First, the authors noticed the residual screw holes, which could weaken the bone stiffness after the syndesmotic screw removal, and performed their study regarding this issue. However, they overlooked the residual screw holes after the plate removal. If the patients ask for removal of the plate after bone healing because of their special culture or religious beliefs, which is relatively common in orient countries, there would be new screw holes, which could also result in a potential fracture with early weightbearing. In addition, we would like to know whether all patients with isolated syndesmosis injuries would consent to the application of an additional plate to increase the bone stiffness, which could increase the expenditure before the effectiveness is clarified. The long-term-placed lateral fibular plate also could cause irritation of the skin and soft tissue and might further lead to plate exposure and infection. Besides, as the authors stated in their discussion, there are very few reports of a fracture following removal of a syndesmotic screw. We noticed that, in the 2 reports cited by the authors, although the fibular fixation was retained, the tibial fractures through the screw holes still occurred. From the authors’ point of view, should a supplementary tibial plate fixation be used to strengthen the tibia? So, to some extent, we think these problems might weaken the clinical relevance of their study and affect the application of their techniques. Second, although the authors stated that they tested the torsional stiffness about the ankle, it seems that they were testing the torsional stiffness about the proximal tibia. In their study, in the majority of cases, the mode of failure was through a tibia fracture at the point of proximal fixation. We would like to know whether the loading or fixation method was effective and whether the proximal tibial fracture could represent the in vivo situation. We noticed that they placed the foot in 10 degrees of dorsiflexion and 5 degrees of pronation. In this position, it seems more likely to cause syndesmotic injury or related avulsion fractures of the ankle with the rotational forces. We also noticed that a proximalplaced external fixator was used to fix the tibia. We would like to know whether application of the external fixator or the placement site of the external fixator would affect the experimental results. In addition, as reported by other authors, we think a cyclic loading might be more appropriate to simulate the physiologic loading of the ankle during weightbearing activity after surgery. Third, the test parameters used by the authors were not so easy, more or less, to be understood. The authors introduced that measurements of angle of rotation and torque were recorded using the software provided with the MTS machine. We would like to know how the stiffness was defined and calculated. We think that different torques could produce different results of the stiffness. For example, a 5 Nm torque was applied to produce a certain result of the stiffness, and then a 7.5 Nm torque might produce another result. Which torque and rotational angle could be used to calculate the stiffness? We proposed this question because we noticed that the stiffness was not simply calculated by the data of displacement angle and failure torque listed in the table.

Posterior Pilon Fractures

Dear Editor, We read with great interest your recent publication of the article by Dr Klammer et al. In their retrospective study, they identified a subgroup of trimalleolar fractures and termed them posterior pilon fractures. We agree with the authors that some fractures have the characteristics of both pilon fractures and malleolar fractures. Posterior pilon is an interesting term, and this kind of fracture should receive more attention. However, there are some concerns regarding the study. First, the authors gave a detailed description of the lines of these fractures and proposed a classification system according to the fracture lines but didn’t emphasize another important characteristic of a posterior pilon—the existence of impacted fractured fragments, which we believe is a much more meaningful characteristic. To our knowledge, Hansen in 2000 was the first to introduce the term posterior pilon to describe severe trimalleolar fractures with the presence of a fourth fragment located deeper than the avulsed posterior fragment. In 2010, Amorosa et al provided a detailed description of a posterior pilon and introduced their experience in treating this kind of fracture. They emphasized that the impaction of the posterior fragments resulted from axial loading, which is the main causative factor of a classic pilon fracture. So we think that if trimalleolar fractures have no impacted fragments or comminution of the posterior tibial plafond, perhaps it’s improper to classify them as posterior pilon fractures although the fracture lines extend to the medial malleolus. We would like to know whether all types of the posterior pilon fractures contained the impacted fragments in the study by Klammer et al. Second, with regard to reduction of the posterior plafond, Klammer et al mentioned that the affected chondral fragments were anatomically reduced. However, the authors didn’t report whether these chondral fragments were impacted into the proximal cancellous bones and didn’t describe in detail how to anatomically reduce these fragments. Because the chondral fragments usually are located deeply, once the remainder of the posterior fragment is reduced, direct visualization of the articular surface is impossible. In our experience, after the impacted chondral fragment is reduced, the bone defect can be filled with bone allograft; then a 1.5-mm K-wire can be used to drill through the impacted fragment, the anterior cortex of the distal tibia, and the anterior soft tissue on the opposite side until the tail end of the K-wire is in a position just adequate for temporary fixation of the impacted fragment without affecting reduction of the remaining posterior plafond fragment. After the definitive fixation is completed, the K-wire can be removed. Small absorbable screws are also useful for fixation of the chondral fragments. We think these methods can help to reduce the articular surface so as to achieve a better outcome. Third, the authors proposed a classification of posterior pilon fractures, which we think is useful for determining the operative strategy. However, they didn’t provide detailed information about the injury mechanisms of these fractures. It’s not clear how their patients were injured. A sound classification should reveal the injury mechanism. We agree with Amorosa et al that posterior pilon fractures are caused by a combination of rotational and axial forces and should be considered low-energy pilon fractures. With regard to classification, a search of the literature revealed another type of posterior pilon fracture in addition to the 3 types proposed by Klammer et al. Wang et al presented 7 trimalleolar fractures in which the entire medial malleolus was fractured and was connected to the posteromedial fragment as one piece; 2 of these had osteochondral impaction and could be regarded as posterior pilon fractures. Wang et al also proposed the mechanism of this type of fractures. We agree with Klammer et al that a large number of patients are needed for future studies to clarify the classification. Fourth, the authors stated that tibiofibular syndesmotic injury presenting concurrently with a posterior pilon fracture had not been described previously in the literature. However, in 2010, Amorosa et al reported on 5 patients with posterior pilon fractures who underwent syndesmotic fixation because of instability of the tibiofibular joint. Klammer et al proposed that the mechanism leading to syndesmotic disruption is probably secondary to excessive ankle dorsiflexion. We don’t agree: External rotation might play a more important role in the syndesmotic injury associated with a posterior pilon fracture. It seems that ankle plantar flexion is more likely to lead to impaction of the posterior plafond than is ankle dorsiflexion.

Limitations of Percutaneous Osteotomy for Malunited Tongue-Type Calcaneal Fractures

Dear Editor: We read with great interest your recent publication of the article by Heng et al. They described a novel percutaneous osteotomy for malunited tongue-type calcaneal fractures. They concluded that their technique can be performed via small incisions to avoid the potential complications associated with the extensile lateral approach. They presented a very nice work. However, there are some concerns regarding their study. First, in the conclusion section of the article, the authors stated that the case they presented was a malunited tongue type fracture. As is known, the fracture would not be united completely within 6 weeks. Strictly speaking, it might be more appropriate to categorize this kind of fracture as a malreduced tongue type fracture. Second, we think their technique would be more suitable for the malunited tongue-type fractures without subtalar arthritis. For the fractures involving the articular surface, the post-traumatic arthritis could not be ignored. In fact, for impacted injuries, irreversible damage to the articular cartilage may occur at the time of initial injury. Post-traumatic arthritis might occur in malreduced and malunited calcaneal fractures with the cartilage damaged. For calcaneal malunion combined with subtalar arthritis, subtalar fusion should be taken into consideration. While, it seems that it is impossible to perform the subtalar fusion through the incisions described by the authors. Third, regarding the incisions for malunited calcaneal fractures requiring arthrodesis, we want to present an opinion of our own. Although CT scan and MRI are helpful for identifying the subtalar arthritis, we think it would be better to make a decision of arthrodesis on the basis of the intraoperative observation. The sinus tarsi approach or extensile lateral approach, which allows direct visualization of the articular cartilage, would be more suitable for the case that subtalar arthritis is doubted preoperatively. Sincerely,

Limitations of minimal incision technique for tibiotalocalcaneal arthrodesis.

Dear Editor: We read with great interest the article titled “Minimal incision surgery for tibiotalocalcaneal arthrodesis” by A. Carranza-Bencano et al. They described a novel MIS (minimal incision surgery) approach for tibiotalocalcaneal arthrodesis. They concluded that this technique would seem to be a safe way to manage hindfoot deformities in complex patients. It without question that they did a very good job. However, there are some concerns regarding this study. First, the portals are so small (about 1 cm each) that details of the joint deterioration cannot be visualized. As is known, the surgical plan and even the necessity of arthrodesis are both determined by the status of the joint surface. In addition, we think that intraoperative fluoroscopy alone is not sufficient for the operative strategy. Second, because of the irregularity and complexity of the ankle and the subtalar joint, the articular cartilage may be removed incompletely from the bone without direct vision through the small incisions, which will result in poor integration and low fusion rate. An appropriate incision that can provide good exposure of the ankle and the subtalar joint seems to be much more important regarding the debridement. Given that complete removal of the cartilage is essential when using this technique, we think that intraoperative endoscopy might be helpful. Third, we would like to know how the cartilage is taken out of the articular cavity entirely through such small incisions. The remaining osteocartilaginous slurry might influence the bony union. Sincerely,

AO and Lauge-Hansen Classification Systems for Ankle Fractures:

Dear Editor: We read with great interest your recent publication of the article by Rodriguez et al. In their study, they explored the relationship between the injury mechanism and the 2 common classification systems of ankle fractures. The idea to perform such a study via the videos posted on YouTube.com is so wonderful. However, there are some concerns regarding this study. First, regarding the Lauge-Hansen classification of radiograph, we have different opinions. For patient 7, patient 13, and patient 21, who had AO 44B fractures, the authors classified the fractures as the Lauge-Hansen pronation external rotation (PER) fractures. However, as is known, AO 44B fractures usually refer to Lauge-Hansen supination external rotation (SER) fractures or pronation abduction (PAB) fractures. We would like to know why the authors categorized these fractures as PER fractures. Second, we do not think it is proper to enroll the 3 patients who had AO 43A1 fractures in their study. The extra-articular fractures of the distal tibia should be excluded from this study. It seems inappropriate to classify the extraarticular fractures of the distal tibia using the Lauge-Hansen classification system. Third, the consistency of 81% (21/26) for the AO classification system might be not correct. In their study, when the AO classification was used, all 12 supination-adduction (SAD) type injuries had a 44A type fracture, whereas the 14 PER injuries resulted in nine 44B fractures, two 44C fractures, and three 43A fractures. As the authors stated in the discussion of their article, they correlated the PER mechanism to the AO 44B fractures. Then what about the AO 44C fractures? In our opinion, it is more appropriate to correlate the PER mechanism to the AO 44C fractures. As a result, the consistency for the AO classification system should be 54% (14/26). If the 3 AO 43A fractures are excluded, the result will be changed accordingly. Fourth, not all ankle fractures can be classified using the Lauge-Hansen classification system. In the literature, a special ankle fracture with the whole posterior tibial plafond involved through a mechanism of hyperplantarflexion has been described by other authors. We would like to know whether some patients had this kind of fractures in the authors’ cases. We think maybe this injury mechanism also ought to be considered in such a study.

Mitchell's osteotomy for hallux valgus: comment on Kalender AM, et al. Mitchell's osteotomy with mini-plate and screw fixation for hallux valgus.

Dear Editor, We read with great interest your recent publication of the article by Kalender et al. In their retrospective study, these authors used mini-plate and screw to stabilize the first metatarsal osteotomy in patients undergoing Mitchell bunionectomy. They concluded that this fixation was a safe alternative method for osteotomy fixation in Mitchell’s osteotomy in hallux valgus (HV) surgery. However, there are some concerns regarding their study. First, although the plate fixation could provide stable fixation to avoid cast immobilization and secondary osteotomy displacement, there are some disadvantages with this method. (1) Mini-plates are more expensive than screws. (2) Mini-plates require more soft tissue stripping, thus increasing the invasiveness of the procedure. (3) Mini-plates are more prone to induce soft tissue irritation, such as the extensor hallucis longus tendon. In our opinion, single screw fixation could provide sufficiently stable fixation and avoid the above disadvantages. Huang et al used multipleuse compression screws to fix the first metatarsal osteotomy in 95 patients (137 feet) who underwent Mitchell’s osteotomy to correct HV. The patients were allowed to walk with special shoe insole on the day after surgery. The stabilization was satisfactory, and no serious complications occurred. Second, Kalender et al didn’t mention whether the distal soft tissue was released when they performed Mitchell’s osteotomy to correct HV. We would like to know the indications for an additional distal soft tissue release. In our opinion, in some selective cases, soft tissue release (modified McBride procedure) combined with osteotomy can give a better result. The soft tissue procedures can reposition the displaced sesamoids and avoid recurrence of the deformity. It has been reported in the literature that the modified McBride procedure combined with osteotomy of the first metatarsal results in satisfactory outcomes. Third, in the radiograph images provided by the authors, a shorter first metatarsal occurred after the operation. Transfer metatarsalgia, a common complication of HV, often occurs postoperatively because of shortening of the first metatarsal. We think that the direction of the osteotomy is very important for performing a Mitchell’s osteotomy. Dorsiflexion of the metatarsal head and excessive shortening of the metatarsal should be avoided. Once a shorter first metatarsal occurred after the osteotomy and fixation, a Weil’s osteotomy of the lesser metatarsal heads should be performed. Sincerely,

Effect of second toe-to-hand transfer on the plantar pressure distribution of the donor foot

ABSTRACT Objective: To investigate the effect of second toe-to-hand transfer on the plantar pressure distribution of the donor foot. Methods: Twelve normal fresh-frozen cadaveric foot specimens were subjected to an axial load of 600 N. An F-Scan plantar pressure analysis system was used to measure the forefoot plantar pressure. The testing was performed under the conditions of intact second toe, second toe removal with the second metatarsal head reserved, and second toe removal in combination with the distal one-third of the second metatarsal, respectively. Results: The peak pressure of the second metatarsal head was greater than other four forefoot plantar regions. There was no statistically significant change in the forefoot plantar pressure distribution after the second toe was removed (p > 0.05). When the second toe and the distal one-third of the second metatarsal were removed, the forefoot plantar pressure distribution changed significantly (p < 0.05). Conclusions: An intact second metatarsal is essential for the normal distribution of plantar pressure. Removal of the second toe with the second metatarsal head reserved had little influence on the plantar pressure distribution of the donor foot. Removal of the second toe and distal one-third of the second metatarsal resulted in abnormal plantar pressure distribution. Level of Evidence II, Experimental Study.