Xiang Geng

Mobility of the first metatarsal-cuneiform joint in patients with and without hallux valgus: in vivo three-dimensional analysis using computerized tomography scan

BackgroundHallux valgus (HV) deformity is closely correlated to the hypermobility of the first metatarsal-cuneiform joint, but adequate understanding of the three-dimentional (3D) mobility of this joint in normal or HV feet is lacking. This study was conducted to investigate the mobility of the first metatarsal-cuneiform joint in multiple planes during body weight-bearing conditions for both normal and HV patients.MethodsA total of 10 female volunteers (20 feet) and 10 female HV patients (20 feet) participated in this study. Using a custom-made foot-loading device, computerized tomography (CT) scans of each pair of feet were taken under both unloaded and body weight-bearing conditions. 3D models were reconstructed for the first metatarsal and the medial cuneiform. Rotational and translational motions of the first metatarsal-cuneiform joint in multiple planes from unloaded to loaded conditions were quantitatively evaluated by reverse-engineering software.ResultsDuring body weight-bearing conditions, the first metatarsal-cuneiform joint in HV feet dorsiflexed at an average of 2.91° (standard deviation, SD 1.71) versus 1.18° (SD 0.47) in controls (t = 4.158, P = 0.001); supinated 2.17° (SD 2.28) versus 0.98° (SD 0.81) in controls (t = 2.080, P = 0.045); and internally rotated 2.65° (SD 2.22) versus 0.96° (SD 0.57) in controls (t = 3.114, P = 0.006). Moreover, the joint in HV feet widened significantly compared with the controls (t = 2.256, P = 0.030) and tended to translate more in the dorsal-plantar direction (t = 1.928, P = 0.063); the translation in the medial-lateral direction was not significantly different between the two groups.ConclusionsDuring weight-loading process, the first metatarsal-cuneiform joint turns dorsiflexed, supinated, and internally rotated. For HV feet, hypermobility of the first metatarsal-cuneiform joint can be observed in multiple planes. This study promotes further understanding of the physiological and pathological mobility of the first metatarsal-cuneiform joint.

Lateral Sesamoid Position Relative to the Second Metatarsal in Feet With and Without Hallux Valgus: A Prospective Study.

We sought to determine whether hallux valgus displaces the sesamoid bones laterally away from a stationary first metatarsal or whether the first metatarsal head is displaced medially from the stationary sesamoids, which remain in position relative to the rest of the forefoot. We reviewed weightbearing radiographs in the dorsal plantar view of 128 consecutive patients (149 feet) seen over 2 months in 2014. Of these, 82 feet (55%) had a hallux valgus angle of >15° (hallux valgus group) and 67 feet (45%) had an angle of no more than 15° (control group). We measured the absolute distances from the center of the lateral sesamoid and the first metatarsal head to the long axis of the second metatarsal. Next, the relative distances, defined as the ratio of these 2 absolute distances to the length of the second metatarsal, were calculated to adjust for foot size. Both the absolute and the relative distances from the center of the first metatarsal head to the second metatarsal differed significantly between the 2 groups and correlated positively with the hallux valgus angle and first intermetatarsal angle. However, neither the absolute nor the relative distance to the lateral sesamoid bone differed significantly between the groups, nor did they correlate with either of the 2 angles. Thus, despite medial shifting of the first metatarsal in hallux valgus, the lateral sesamoid retains its relationship to the second metatarsal in transverse plane. Its apparent lateral movement is a radiographic misinterpretation. Awareness of this misinterpretation should improve the success of corrective surgery.

Anatomy of the Sural Nerve With an Emphasis on the Incision for Medial Displacement Calcaneal Osteotomy

An inappropriately positioned skin incision for medial displacement calcaneal osteotomy can put the sural nerve at risk; however, unanimous agreement has not been reached about the optimal strategy for making this incision. In the present cadaveric study, 20 cadaveric specimens were dissected to describe the anatomic course of the sural nerve within the operative area and to provide a more practical reference for surgeons to make a safe incision. The following points were used in the analyses: point A, the tip of the lateral malleolus; point B, the inferior margin of the calcaneus on the plumb line through point A; point C, the posteroinferior margin of the calcaneus; and point D, the lateral border of the Achilles tendon on the same level (collinear) with point A. With careful dissection, the distances of the sural nerve to points A and B in the vertical direction (lines D1 and D2, respectively), to points A and C in the diagonal direction (lines D3 and D4, respectively), and to points A and D in the horizontal direction (lines D5 and D6, respectively) were measured. The landmarks were identified and the distances measured by 3 independent researchers. The median ratio of D1 to D1+D2, D3 to D3+D4, and D5 to D5+D6 was 0.36 (range 0.20 to 0.47), 0.26 (range 0.19 to 0.32), and 0.43 (range 0.34 to 0.52), respectively. Accordingly, we believe it is relatively safe to make an oblique incision that runs through the point that is no less than one third of the distance from the tip of the lateral malleolus to the posteroinferior margin of the calcaneus.

The impact of high-heeled shoes on ankle complex during walking in young women-In vivo kinematic study based on 3D to 2D registration technique.

OBJECTIVE To explore the accurate in vivo kinematic changes in the ankle complex when wearing low- and high-heel shoes (LHS and HHS, respectively). MATERIALS AND METHODS Twelve young women were tested unilaterally. Three-dimensional models of the tibia, talus, and calcaneus were first created based on CT scan results. The subjects walked at a self-controlled speed in barefoot, LHS (4cm), and HHS (10cm) conditions. A fluoroscopy system captured the lateral fluoroscopic images of the ankle complex. The images of seven key positions in the stance phase were selected, and 3D to 2D bone model registrations were performed to determine the joint positions. The mean of 6 degree of freedom (DOF) range of motions (ROM), joint positions, and angular displacements of the ankle complex during the gait were then obtained. RESULTS For the talocrural joint, the rotational ROMs of the subjects either in LHS or HHS condition displayed no significant difference from those in barefoot condition. For the subtalar joint, all the rotational ROMs in the HHS condition and the internal/external rotations in the LHS condition significantly decreased compared with those in the barefoot condition. The talocrural joint was positioned significantly more plantarflexed, inverted, internally rotated, and posteriorly seated in all seven poses in HHS condition, compared with those in barefoot condition. CONCLUSION HHS mainly affected the rotational motion of the ankle complex during walking. The talocrural joint position was abnormal, and the subtalar joint ROM decreased during the gait in HHS condition. Only a few kinematic changes occurred in LHS condition relative to the barefoot condition.

In vivo kinematic study of the tarsal joints complex based on fluoroscopic 3D-2D registration technique

The tarsal bones articulate with each other and demonstrate complicated kinematic characteristics. The in vivo motions of these tarsal joints during normal gait are still unclear. Seven healthy subjects were recruited and fourteen feet in total were tested in the current study. Three dimensional models of the tarsal bones were first created using CT scanning. Corresponding local 3D coordinate systems of each tarsal bone was subsequently established for 6DOF motion decompositions. The fluoroscopy system captured the lateral fluoroscopic images of the targeted tarsal region whilst the subject was walking. Seven key pose images during the stance phase were selected and 3D to 2D bone model registrations were performed on each image to determine joint positions. The 6DOF motions of each tarsal joint during gait were then obtained by connecting these positions together. The TNJ (talo-navicular joint) exhibited the largest ROMs (range of motion) on all rotational directions with 7.39±2.75°of dorsi/plantarflexion, 21.12±4.68°of inversion/eversion, and 16.11±4.44°of internal/external rotation. From heel strike to midstance, the TNJ, STJ (subtalar joint), and CCJ (calcaneao-cuboid joint) were associated with 5.97°, 5.04°, and 3.93°of dorsiflexion; 15.46°, 8.21°, and 5.82°of eversion; and 9.75°, 7.6°, and 4.99°of external rotation, respectively. Likewise, from midstance to heel off, the TNJ, STJ, and CCJ were associated with 6.39, 6.19°, and 4.47°of plantarflexion; 18.57°, 11.86°, and 6.32°of inversion and 13.95°, 9.66°, and 7.58°of internal rotation, respectively. In conclusion, among the tarsal joints, the TNJ exhibited the greatest rotational mobility. Synchronous and homodromous rotational motions were detected for TNJ, STJ, and CCJ during the stance phase.

Comparison of the incisions for the open surgical treatment of gluteal muscle contracture.

Gluteal muscle contracture is not very common, but cases are still seen in China. Open surgical treatment is considered as an efficient method to treat this disease. However, the type of incision that can provide best results is yet to be determined. The authors therefore compared various incisions to determine the better one. In this retrospective study, patients who underwent surgery with a traverse straight incision, a curved incision, a longitudinal straight incision, or an ‘S’-shaped incision above the greater trochanter were enrolled and divided into four groups: A, B, C, and D. In each group, the patients were divided into different levels according to a specific standard. The four groups were compared in terms of incision length, postoperative drainage amounts, wound healing rates, visual analog scale scores, and improvement in the degree of range of motion (ROM). During the follow-up period, the validity of the results, complications, and recurrent cases were evaluated. In our study, incision length and visual analog scale score of the four groups showed no significant differences (P>0.05). Wound healing rates, drainage amount, improvement in ROM, validity of the results, and recurrences in group D were significantly the best (P<0.05). No significant differences in wound healing rates, drainage amount, and improvement in ROM were found in groups A, B, and C. In terms of validity of the results and 1-year recurrence, no significant difference was observed between groups A and B; however, these factors were better than those in group C. We concluded that the ‘S’-shaped incision above the greater trochanter is the most efficient among the incisions described in this study. This incision has the following advantages: clear exposure, less damage, high safety rate, excellent results, and low recurrence rate.

Osteochondroma of the Talar Neck: A Case Report and Literature Review

Osteochondroma occurs most frequently in the long bones such as the proximal humerus, tibia, and distal femur. It is rare for it to originate in the talar neck. In the present case report, we describe a case of osteochondroma arising from the talar neck. Furthermore, a review of the published studies of talar osteochondroma was performed to obtain a better understanding of the symptoms, diagnosis, and treatment of this unusual entity.

Gender Variation in the Shape of Superior Talar Dome: A Cadaver Measurement Based on Chinese Population

Understanding the shape of superior talar dome is essential for a better size compatibility between talar component of ankle implant and bone. The purpose of this study was to determine whether there were gender variations in (1) width (TW) and length (TL) of talus, as well as anterior width (DAW), middle width (DMW), posterior width (DPW), and length (DL) of superior talar dome; (2) differences between the DAW, DMW, and DPW; (3) the ratios between these parameters. Fifty-one cadaveric ankle specimens were included. Two observers measured all the specimens using vernier caliper. Intraclass correlation coefficients (ICCs) were used for intraobserver and interobserver reliability analysis and the reliability was thought to be good if the ICC>0.75. A two-tailed unpaired t-test or the rank-sum test was used to investigate gender variations. A single-factor ANOVA was utilized to identify the differences between the width of the superior talar dome surface and p value of <0.05 was considered significant. Intraobserver and interobserver reliability were good. Significant gender variations were found, in which TW, TL, DAW, DMW, DPW, and DL of female specimens were much smaller than those of male. The width of talar dome linearly decreased from DAW to DPW; however, the linearly decreased rate from anterior to posterior width was bigger in female. Moreover, significant differences were found in DAW/DPW, DMW/DPW, DL/DAW, DL/DMW, and DL/DPW between male and female. Based on our result, there was no difference in the 2D shape of the whole talus instead gender variation existed in the 2D shape of superior talar dome between male and female. The current 2D data could contribute to figure out more suitable size of talar component for Chinese population and might indicate a gender-specific shape of bone-implant interface, which could reduce the potential bone-component incompatibility when performing ankle replacement using standard component.

Sustentacular screw placement with guidance during ORIF of calcaneal fracture: an anatomical specimen study

BackgroundThe sustentacular screw is essential to maintain the stability of the subtalar joint during ORIF (open reduction with internal fixation) of calcaneal fractures. Currently, the screw is still inserted based on surgeons’ anatomical experiences and nearly 40% of screws are misplaced from the sustentaculum. Previous studies demonstrated some methods of sustentacular screw placement through anatomical measurements or navigation system. The purposes of this study are to design an assistant guidance device that can effectively improve the accuracy of sustentacular screw placement and to compare the accuracy of this technique with traditional screw placement based on experience.MethodsA customized guidance device is designed, aiming to improve the accuracy of sustentacular screw placement. Twenty cadaveric specimens are used in the present study. Ten specimens are allocated into the guidance-assisted group, and others are included in the traditional screw insertion group. A total of 40 sustentacular screw placements are performed in each group. Fluoroscopic images are obtained after each screw placement. Only the screw that captures the sustentaculum both on the lateral and axial X-ray views was regarded as an accurate placement.ResultsThe accuracy rate in the guidance-assisted group is 87.5% (35 out of 40 times of insertions) while in the traditional screw insertion group, the accuracy rate is 65% (26 out of 40 times of insertions). A significant difference is found between the two groups (p = 0.018).ConclusionsThe guidance-assisted technique is a convenient approach that can effectively improve the accuracy of sustentacular screw placement during the ORIF of calcaneal fractures. This study provides a novel technique that significantly facilitates sustentacular screw insertion and improves its accuracy.

Loading pattern of postoperative hallux valgus feet with and without transfer metatarsalgia: a case control study

BackgroundPostoperative transfer metatarsalgia is a common complication after hallux valgus surgeries. Shortening of the first metatarsal is traditionally thought to be the primary cause of it. However, we speculate the abnormal loading pattern during gait is the real reason. This study is to determine specific differences in the loading patterns between reconstructive hallux valgus (HV) feet with and without postoperative transfer metatarsalgia, so as to find risky loading characteristics of this complication.MethodsThirty feet with postoperative transfer metatarsalgia were recruited as pain group, while another 30 postoperative feet without pain as controls. All participants were asked to walk barefoot at self-selected speed through a plantar force measuring plate (Rs-Scan Inc.) for three times. Certain plantar load variables were recorded or calculated, and their differences between two groups were compared.ResultsFor pain group, the maximum plantar force and force time integral of the first metatarsal decrease significantly; the force time integral of the central rays (second plus third metatarsal) does not significantly differ with that in the controls, but their cumulative load percentage to the whole foot is higher. In pain group, the time point when central rays reached their peak force during the push-off is significantly later than that in controls. And the regional instant load percentage at this moment presented significantly higher for central rays, while significantly lower for the first metatarsal and the hallux compared to the controls.ConclusionsFor hallux valgus feet with postoperative metatarsalgia, the load function of the first metatarsal is obviously impaired. But for central rays, indicative difference is not reflected in either peak or cumulative load during the gait cycle, but in the instant load distribution when central rays reach their peak load. So we can conclude that whether the remaining regions can adequately share certain load during walking, especially around the time metatarsalgia often occurs, plays an unnegligible role. So surgeons should pay more attention to reconstruct a foot where load can be evenly distributed.