Lateralizing calcaneal osteotomy performed with a percutaneous burr results in a significantly lower increase in tarsal tunnel pressure

PURPOSE

Tarsal tunnel syndrome is well documented following lateralizing calcaneal osteotomy to manage varus hindfoot deformity. Traditionally, calcaneal osteotomy is performed with an oscillating saw. No studies have investigated the effect of alternative surgical techniques on postoperative tarsal tunnel pressure. The purpose of this study was to investigate the difference in tarsal tunnel pressures following lateralizing calcaneal osteotomy performed using a high-torque, low-speed "minimally invasive surgery" (MIS) Shannon burr versus an oscillating saw.

METHODS

Lateralizing calcaneal osteotomy was performed on 10 below-knee cadaveric specimens. This was conducted on 5 specimens each using an oscillating saw (Saw group) or MIS burr (Burr group). The calcaneal tuberosity was translated 1 cm laterally and transfixed using 2 Kirschner wires. Tarsal tunnel pressure was measured before and after osteotomy via ultrasound-guided percutaneous needle barometer. Mean pre/post-osteotomy pressures were compared between groups. Differences were analyzed using Student's t test.

RESULTS

The mean pre-procedure tarsal tunnel pressure was 25.8 ± 5.1 mm Hg in the Saw group and 26.4 ± 4.3 mm Hg in the Burr group (p = 0.85). The mean post-procedure pressure was 63.4 ± 5.1 in the Saw group and 47.8 ± 4.3 in the Burr group (p = 0.01). Change in tarsal tunnel pressure was significantly lower in the Burr group (21.4 ± 4.5) compared to the Saw group (37.6 ± 12.5) (p = 0.03). The increase in tarsal tunnel pressure was 43% lower in the Burr group.

CONCLUSION

In this cadaveric study, tarsal tunnel pressure increase after lateralizing calcaneal osteotomy was significantly lower when using a burr versus a saw. This is likely because the increased width ("kerf") of the 3 mm MIS burr, compared to the submillimeter saw blade width, causes calcaneal shortening. Given the smaller increase in tarsal tunnel pressure, using the MIS burr for lateralizing calcaneal osteotomy may decrease the risk of postoperative tarsal tunnel syndrome. Future research in vivo should explore this.

The Surgical Correction of Cavovarus Deformity in Charcot-Marie-Tooth Disease

Charcot-Marie-Tooth (CMT) disease is the most commonly inherited neuropathy. CMT disease is a motor-sensory neuropathy with multiple genotypes. By comparison, the phenotypic expression is more uniform, with two main presentations. Most patients who need surgical care have progressive cavovarus foot deformity, with muscle imbalance causing a nonplantigrade foot, soft-tissue contractures, and abnormal bone morphology. Surgical treatment can be life-changing for these patients, allowing them to walk potentially brace free with more endurance and less pain. Early realignment procedures may reduce progression of joint arthritis. A minority of patients have diffuse paralysis below the knee. These patients are best treated with ground-reaction ankle-foot orthoses. This review article is based on the senior author's extensive experience with CMT, along with the limited evidenced-based literature.

Patient Satisfaction and Pain Relief After Deep Peroneal Nerve Neurectomy for Midfoot Arthritis: A Preliminary Short Report

BACKGROUND

The deep peroneal nerve (DPN) plays a role in afferent nociceptive dorsal midfoot joint pain perception. DPN neurectomy for treatment of symptomatic dorsal midfoot osteoarthritis allows early mobilization and weightbearing. The purpose of our study was to evaluate the patient satisfaction and pain relief after DPN neurectomy for treatment of chronic dorsal midfoot pain due to osteoarthritis.

METHODS

In this retrospective, IRB-approved, questionnaire-based study, we evaluated 48 patients (55 feet) with an average follow-up of 35.1 (range, 16-51) months who underwent DPN neurectomy at our institution between September 2017 and February 2021. There were 38 women and 10 men, 41 unilateral (22 right, 19 left) and 7 bilateral procedures, with an average age of 67.8 (range, 35-88) years at the time of surgery. A questionnaire that included questions regarding postsurgical dorsal midfoot pain relief, surgical result satisfaction, and current functional limitations was administered via telephone. Demographic information, patient responses, and complications were recorded.

RESULTS

Of the 48 patients, 80.8% were satisfied with the result of the surgery in relieving their dorsal midfoot pain, 84.6% would repeat the surgery under the same circumstances, 83.8% would recommend the surgery to a friend, 10.4% reported they wish they had undergone arthrodesis, 91.7% reported pain relief in the first 6 months, and 55.6% reported current activity limitations. Six feet (10.9%) underwent a second procedure with an average postoperative time of 20.5 (range, 1-36) months. Complications included 1 hematoma and deep wound infection, 1 DPN neuroma and superficial peroneal nerve entrapment, and 4 patients with inadequate pain relief.

CONCLUSION

In this cohort, DPN neurectomy appeared to be a reasonable surgical alternative to arthrodesis for the management of chronic dorsal midfoot pain due to midfoot osteoarthritis after failed nonoperative management.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Contemporary Review: Autograft Bone Use in Foot and Ankle Surgery

Bone autografts are frequently harvested for use in foot and ankle surgery. A commonly used harvest site is the iliac crest; however, because of known morbidity with this site, the tibia and calcaneus are attractive alternatives. There remains limited understanding regarding the osteogenic potential of autografts from each of these locations. In this review, we provided an update of the known data on bone autografts from the iliac crest, tibia, and calcaneus, focusing on the total cells harvested from each site as well as the presence of osteogenic osteoprogenitor cells.

Level of Evidence

Level V, expert opinion.

Measuring Deltoid Insufficiency After Supination-External Rotation Ankle Fracture With Lateral Talar Subluxation on Gravity Stress View

BACKGROUND

Stress-view radiographs are frequently obtained to evaluate supination-external rotation (SER) variant ankle fractures. Measurement of the ankle medial clear space (MCS) is a surrogate of medial structure integrity as part of overall ankle stability. Measurement of the lateral talus displacement with respect to the incisura may be a sensitive and specific method to assess joint subluxation.

METHODS

Retrospective review of acute SER-variant isolated lateral malleolar fractures with gravity stress views (GSVs) were performed for 103 patients. GSV analysis was performed with standardized measurements of the MCS, superior clear space (SCS), and 2 new novel measurements of lateral talus subluxation (LTS). Decision for surgery was obtained by surgeons who reviewed masked injury radiographs for predictive performance analysis of the LTS vs MCS.

RESULTS

MCS, SCS, and LTS measurements were performed on 103 patients. Mean MCS, SCS, and LTS within the operative group was increased. MCS ≥5 mm and LTS >4 mm had equal sensitivity (95%), with higher specificity for LTS (75% vs 60%). Receiver operating characteristic analysis demonstrates an area under the curve of 0.786 for MCS ≥5 mm vs 0.918 for LTS >4 mm.

CONCLUSION

We found LTS to be superior to MCS for medial ankle structure stability on gravity stress views of SER-variant ankle fractures. We propose this as a useful tool for clinicians to consider when evaluating SER-variant ankle fractures.

LEVEL OF EVIDENCE

Level II, prospective comparative study of radiographs.

Durability and Safety of Deep Peroneal Nerve Neurectomy for Midfoot Arthritis at Midterm Follow Up

Category:

Midfoot/Forefoot

Introduction/Purpose:

Midfoot osteoarthritis affects up to 12% of the adult population greater than 50 years old. Arthrodesis is the traditional surgical procedure performed when nonoperative management fails but is a technically demanding procedure that requires prolonged postoperative immobilization and is not uncommonly complicated by nonunion or deep infection. The deep peroneal nerve (DPN) plays a significant role in afferent nociceptive midfoot joint pain perception, most consistently in the second and third tarsometatarsal joints and the naviculocuneiform joint. Early outcomes following DPN neurectomy have demonstrated promising results as a safe and effective treatment that allows early mobilization and weight bearing. The purpose of our study was to evaluate the mid-term patient satisfaction and pain relief after DPN neurectomy for treatment of chronic midfoot pain due to osteoarthritis.

Methods:

In this retrospective IRB-approved questionnaire-based study, we evaluated 49 out of 95 patients identified (56 feet) with an average follow-up of 34.6 (range, 9 to 51) months, who underwent DPN neurectomy (Figure 1) at our institution between September 2017 and February 2021. There were 39 women and 10 men, 42 unilateral (23 right, 19 left) and 7 bilateral procedures, with an average age of 67.9 (range, 35 to 88) years at the time of surgery. A questionnaire which included questions regarding post-surgical dorsal midfoot pain relief, surgical result satisfaction, and current functional limitations was administered via telephone. Demographic information, patient responses, and complications were recorded.

Results:

There was an 81.2% patient satisfaction with the result of the surgery in relieving their dorsal midfoot pain. Of the 49 patients, 84.9% would repeat the surgery under the same circumstances, 84.1% would recommend the surgery to a friend, 10.2% reported they wish they had undergone arthrodesis, 8.2% reported no pain relief in the first 6 months, and 55.8% reported current activity limitations because of dorsal midfoot pain. Six feet (10.7%) underwent a second procedure with an average postoperative time of 20.5 (range, 1 to 36) months. Complications include one patient with deep wound infection, one DPN neurectomy revision and burial into bone, one DPN neuroma excision, one midfoot exostosis excision, and two conversions to arthrodesis. Theoretic complications of neuroarthropathy, midfoot collapse, and development of lesser toe deformities were not observed.

Conclusion:

DPN neurectomy is a safe and effective surgical option for the management of chronic dorsal midfoot pain due to midfoot osteoarthritis after failed nonoperative management. At midterm follow-up, patients who underwent dorsal midfoot denervation reported acceptable satisfaction rates, similar to those reported for arthrodesis, with associated improved functional outcomes and few complications.

Measuring Deltoid Insufficiency after Supination-External Rotation Ankle Fracture with Lateral Talar Subluxation on Gravity Stress View

Category:

Trauma; Ankle

Introduction/Purpose:

Supination-external rotation (SER) variant ankle fracture is common, and identifying the unstable SER variants requiring surgery has been controversial. Stress view radiographs are frequently obtained to assist in decision-making. Measurement of the medial clear space (MCS) is used to determine medial structure integrity. SER variant ankle injuries are characterized by talus external rotation, and posterolateral translation causing a posterior displaced distal fibula fracture, with possible medial and posterior injury at further subluxation events. We propose that the MCS measurement is flawed by measuring from the point of rotational pivoting. Measurement of lateral displacement of the lateral talus versus the tibial plafond will be a more sensitive measurement tool for an injury mechanism characterized by external rotation and posterolateral subluxation.

Methods:

IRB-approved, retrospective review of ankle injury radiographs for acute SER-variant isolated lateral malleolar fractures during a 3-year consecutive period. Patients were included if they had a gravity-stress view (GSV) evaluation. Patients were excluded for different fracture morphology, pediatric fractures, no GSV films, or prior history of ankle or foot arthritis or trauma. A priori power analysis was performed demonstrating 32 patients would be required to detect a change in 2mm. 102 patients underwent analysis. GSV were analyzed with measurements taken of the medial clear space (MCS), superior clear space (SCS), and we propose two novel measurements of lateral talus subluxation (LTS) by comparison to the anterior ankle syndesmosis marked by a vertical line at the tibial plafond. Standardized measurements were acquired by foot-and-ankle fellowship-trained orthopaedic surgeons and musculoskeletal radiologists. ICC data was obtained. Surgeons separately provided blinded decisions- for-surgery which patients appeared to have ankle instability requiring surgical stabilization.

Results:

Measurements were performed for 102 patients, there were no significant differences in baseline demographics. There was a statistically significant increase in mean MCS, SCS, and LTS within the operative group (MCS 7.3 vs 5, p=0.005, SCS 4.6 vs 3.9, p=0.02, LTS 6.1 vs 2.9, p <0.001) with the LTS having the highest statistical significance. Pearson correlation analysis demonstrated positive and significant correlations between MCS and SCS (0.43, 0.37, P<0.001), MCS and LTS (0.51, p<0.001). MCS >=5mm had a sensitivity of 95% and specificity of 60% in our cohort, LTS >4mm demonstrating the same sensitivity (95%) with improved specificity to 75%. Receiver-operator-characteristic analysis for MCS vs LTS demonstrates an area under the curve (AUC) 0.786 for MCS >4 versus LTS (AUC) 0.918.

Conclusion:

The LTS measurement is superior to MCS measurement as a surrogate for medial ankle structure stability. We propose that ankle joint subluxation can be more accurately identified by measuring nearer to the point of maximal talar displacement in an external rotation and posterolaterally displacing injury pattern. The LTS measurement elevation >4mm was found to be superior to the MCS measurement >4mm in all categories, with high sensitivity and specificity, and superior performance in ROC analysis. We propose this will be a useful tool for clinicians when evaluating SER variant ankle fractures.

Traumatic Great Toe Mcl Avulsion in Professional Athlete Treated Surgically with Mcl Repair with Suture Tape Augmentation Allowing Rapid Return to Sport

Category:

Sports; Midfoot/Forefoot; Trauma

Introduction/Purpose:

Acute medial collateral ligament (MCL) tears of the great toe metatarsophalangeal joint (MTPJ) are a rare occurrence. There is minimal literature existing regarding both operative and non-operative management of this pathology, also known as 'traumatic bunion' due to its low incidence. The closest analog is a traumatic ulnar collateral ligament (UCL) rupture in the hand (Skier's thumb). Suture anchor repair with an internal brace has proven to be an effective treatment for thumb UCL tears with rapid rehabilitation and early range of motion. This method has not yet been reported in literature for a weightbearing joint such as the hallux MTPJ. We present a case report for a professional surfer with traumatic great toe MCL avulsion with surgical technique allowing rapid return to sport.

Methods:

We present a case report of a novel technique for this rare traumatic MCL avulsion. Surgical management of the great toe MCL was performed utilizing a pre-loaded interference screw to fixate suture at the MCL origin with suture tape augmentation. A mid-axial medial approach was used with L-shaped capsular flap to expose the MCL. 3-0 braided suture was passed through the proximal avulsed MCL. A drill tunnel was prepared at the MCL origin, and the MCL was repaired to its anatomic origin with an interference screw technique for knotless technique. The interference screw was preloaded with suture tape. The suture tape from the interference screw was passed extra articular and the capsule was repaired. The sutuer tape was then inserted into the MCL insertion on the distal phalanx using a small interference screw and drill tunnel for a suture tape augmentation while the toe was held in neutral MTPJ position.

Results:

He was made weightbearing as tolerated in a CAM boot post-operatively. Immediate active great toe MTPJ motion was permitted. At 2 weeks post-op, sutures were removed, and he was allowed self-directed passive range of motion of the toe, with continued weightbearing as tolerated in the boot. All restrictions were lifted at 4 weeks for a return to play protocol and the patient resumed surfing immediately at that time. His last follow up appointment was at 3 months post-op, at which time he had resumed full activity, had no deformity recurrence, no pain, and his range of motion was symmetric to the contralateral foot. The patient was able to compete at full activity in a national tournament to continue the professional tour at 3 months post- operatively.

Conclusion:

This report demonstrates a novel surgical technique for the treatment of a rare traumatic MCL avulsion of the great toe (the 'traumatic bunion'). In this case of great toe MCL repair in a professional surfer, we utilized a knotless technique to repair the MCL to it's anatomic origin and also provide suture tape augmentation to allow rapid rehabilitation. This report demonstrates rapid return to sport, an excellent outcome, easy rehabilitation, and straightforward surgical technique. More research will be needed to demonstrate the success of this technique in a broader population.

Novel External Fixation Device for the Treatment of Hallux Distal Phalanx Fractures

Category:

Midfoot/Forefoot; Trauma

Introduction/Purpose:

The great toe plays a large role in activity, including maintenance of balance and substantial weight bearing capabilities. Fractures of the hallux distal phalanx, especially when displaced or unstable, can lead to significant dysfunction of the interphalangeal joint (IP) and pain and may need operative intervention. Surgical options include wire pinning, screw fixation, external fixation, arthrodesis, or amputation. For patients with significant comminution and shortening who would like to attempt toe salvage without fusion, external fixation can lead to great outcomes. Unfortunately, the use of these devices is hindered by cost, size, and availability. We recommend the use of a novel low cost external fixation device that can be made intraoperatively using common materials found in the operative room.

Methods:

A 27-year-old female, with a severely comminuted right distal phalanx fracture with interphalangeal (IP) joint dislocation, presented 4 days after a skiing accident. We discussed treatment may require IP joint arthrodesis or partial amputation, however, salvage fixation could be attempted initially. First, a transverse percutaneous wire was placed through the distal phalanx tip since the fragment was still mostly intact. The wire exited the skin medially. Two Kocher clamps to each side of the wire were applied for distraction of the fracture site while simultaneous manual manipulation of the more proximal fragments was performed. Once reduced, three more proximal transverse wires were placed through a 3cc syringe, which acted as a rail to hold the fracture length stable. The distal transverse wire was then impaled through the rail so that all four wires were within the rail providing two points of fixation in the distal phalanx and proximal phalanx.

Results:

The patient's weight-bearing status was non-weight bearing to the right lower extremity for 6 weeks. This was actually being dictated by the more proximal tibial plateau fracture for which she was non-weight bearing. With regard specifically to the hallux fracture, she could have been heel weight beared immediately. At her most recent post-operative visit at 6 weeks, she was doing well with minimal pain. The external fixation device was removed in clinic and she was transitioned to a post-op shoe and allowed to weight bear as tolerated. She was motor and sensate intact with the ability to actively range her IP joint. Radiographs at the most recent visit revealed excellent alignment of the toe with minimal articular step off.

Conclusion:

With severely unstable hallux distal phalanx fractures, operative intervention should be considered. For those with a significant degree of comminution who still would like to undergo salvage fixation, external fixation is an excellent option. Unfortunately, the use of these devices is hindered by cost, size, and availability. Hand surgeons solved this problem by introducing small, low cost external fixators composed of common materials such as needle sheaths, IV cannulas, and syringes. We adapted their model to the toes and were able to obtain great clinical outcomes with low cost, all the while maintaining the patient's expectations for cosmesis.

Proximal Flexor Hallucis Longus Transfer to Peroneus Brevis for Treatment of Peroneal Muscle Paralysis

Category:

Hindfoot; Ankle; Other

Introduction/Purpose:

Equinovarus foot deformities typically present with equinus contractures, hindfoot varus, dorsiflexion of the medial midfoot, and adduction deformities of the forefoot. Whether of neurologic or muscular origin, all forms result muscular imbalance. Flexor hallucis longus (FHL) transfer to peroneus brevis (PB) is indicated when both peroneal muscles are in unrepairable condition to restore active eversion. However, in cases of muscle paralysis where the PB is still in continuity, we recommend a novel technique where FHL is tenodesed proximal to the peroneal retinaculum within the leg to avoid the additional morbidity associated with more distal fixation or tenodesis.

Methods:

Surgical intervention first involved a posterolateral approach to the ankle and an Achilles tendon Z-lengthening to fix her equinus contracture. The ankle and subtalar joint capsules were contracted requiring release. Flexor digitorum longus (FDL) and FHL were tenotomized, which immediately corrected her claw toes. Since the tendon had already been released, we were able to deliver the FHL tendon into the posterolateral leg wound. The peroneal fascia and sheath were opened proximal to the superior peroneal retinaculum to prevent tendon subluxation. PB was identified by confirming that it produced foot eversion and by visualizing the peroneus longus (PL). The tension of PB was confirmed by observing that it did not cause tension at PL insertion on the plantar 1st ray. FHL was then transferred to the PB utilizing a Pulvertaft weave technique with the tendon appropriately tensioned in mid eversion in the middle of the Blix curve (Figure 1).

Results:

After FHL transfer, the patient was immediately allowed to weight bear as tolerated in a short leg cast. This was due to her deconditioned state to limit atrophy and the effects of prolonged recumbency in this medically fragile young woman. The patient ultimately was casted for 10 weeks total as she was unable to tolerate a CAM boot or other orthotic due to the weight and problems with the fit. At 4 months follow up, her foot is corrected and she is able to stand in a neutral, plantigrade position. Using a new AFO, she can walk without issue. Her foot remains well balanced and plantigrade.

Conclusion:

This simple FHL transfer technique decreases morbidity since the transfer occurs within the leg, proximal to the superficial peroneal retinaculum (SPR). The transfer pulls on the paralyzed, but intact PB instead of routing the FHL to the 5th metatarsal base or PB stump. This technique is only recommended if PB is intact but non-functional. It should be noted that adequate tensioning is essential for a successful transfer. Benefits of this procedure include no cluttering under the SPR and no risk of scarring that region which can lead to decreased tendon excursion.

A Systematic Review Comparing Bone Graft Harvest From the Iliac Crest, Tibia, and Calcaneus Donor Sites in Foot and Ankle Surgery

Category:

Basic Sciences/Biologics; Other

Introduction/Purpose:

Bone autografts are frequently harvested for use in foot and ankle surgery. The gold standard harvest site is the iliac crest; however there is known morbidity with this harvest site. Alternative harvest sites include the tibia and calcaneus which are easily accessible for lower extremity surgery. Controversy exists regarding the osteogenic potential of autografts from each location. We performed a systematic review of the known data on cellular autografts from the iliac crest, tibia, and calcaneus focusing on the total cells harvested from each site as well as the presence of the critically important osteogenic osteoprogenitor cells. We also reviewed autograft volume, autograft consistency, surgical techniques, and the morbidities and complications associated with each bone autograft harvest location.

Methods:

In accordance with the PRISMA 2020 guidelines, a literature search of the PubMed, Cochrane Library, Web of Science, and Google databases from inception through January 2022 was performed. The search terms included: 'autograft,' 'bone graft,' 'foot and ankle surgery,' 'iliac crest,' 'tibia,' 'calcaneus,' reamer irrigator aspirator,' 'RIA,' 'mesenchymal cells,' 'osteoprogenitor cells,' 'quantity,' 'number,' 'amount,' 'yield,' 'concentration,' 'surface antigens,' 'surface markers,' 'CD markers.' Studies were included if autologous bone graft was harvested from the iliac crest, femur, tibia, or calcaneus and the cells in the harvest underwent histologic evaluation, quantification, or CD surface antigen identification. We included studies with bone graft as well as bone marrow aspirates used as samples. The nucleated cell and osteoprogenitor cell yield was recorded from each location; and MSC CD markers present at each harvest site were extracted from the eligible studies.

Results:

13 studies met our inclusion criteria. Eight studies performed cell quantification from the harvest sites. Notably these studies only provide counting of total nucleated cells without specific identification of the osteoprogenitors. Colony-forming units were also reported and their findings are reviewed. Total cellular material was on average greatest in the iliac crest, with intermediate counts in the proximal tibia, and lowest in the calcaneus autograft samples. Five studies identified mesenchymal stromal cell (MSC) cluster of differentiation (CD) antigens at the harvest sites of interest. CD markers confirm osteoprogenitor cells are present in each sample location. Total number of osteoprogenitor cells remains unknown, however authors have attempted to extrapolate this number based on number of total nucleated cells and other data.

Conclusion:

Osteoprogenitor cells can be harvested from the iliac crest, tibia, and calcaneus. Greater total nucleated cell yields were identified in harvests from the iliac crest with descending amounts moving location distally in the limb. Nucleated cells were counted to provident estimates of osteoprogenitor cells yields in most studies, with flow cytometry confirmation that osteoprogenitors are present. Strict quantification of osteoprogenitor cells remains unknown. Multiple studies compared cellular material from bone marrow aspirates versus bone graft harvests themselves. Studies with modern techniques are needed to identify the true number of osteoprogenitors in each location.

Abnormal Bone Morphology in Charcot-Marie-Tooth Disease

BACKGROUND

Although long suspected, it has yet to be shown whether the foot and ankle deformities of Charcot-Marie-Tooth disease (CMT) are generally associated with abnormalities in osseous shape. Computed tomography (CT) was used to quantify morphologic differences of the calcaneus, talus, and navicular in CMT compared with healthy controls.

METHODS

Weightbearing CT scans of 21 patients (27 feet) with CMT were compared to those of 20 healthy controls. Calcaneal measurements included radius of curvature, sagittal posterior tuberosity-posterior facet angle, and tuberosity coronal rotation. Talar measurements included axial and sagittal body-neck declination angle, and coronal talar head rotation. Surface-mesh model analysis of the hindfoot was performed comparing the average of the CMT cohort to the controls using a CT analysis software (Disior Bonelogic 2.0). Means were compared with a t test (P < .05).

RESULTS

CMT patients had significantly less talar sagittal declination vs controls (17.8 vs 25.1 degrees; P < .05). Similarly, CMT patients had less talar head coronal rotation vs controls (30.8 vs 42.5 degrees; P < .001). The calcaneal radius of curvature in CMT patients was significantly smaller than controls (822.8 vs 2143.5 mm; P < .05). CMT sagittal posterior tuberosity-posterior facet angle was also significantly different from that of controls (60.3 vs 67.9 degrees respectively; P < .001).Surface-mesh model analysis demonstrated the largest differences in morphology at the navicular tuberosity, medial talar head, sustentaculum tali, and anterior process of the calcaneus.

CONCLUSION

This is the first study to quantify the morphologic differences in hindfoot osteology seen in CMT patients. Patients identified with osseous changes of the calcaneus, especially a smaller axial radius of curvature, may benefit from a 3-dimensional osteotomy for correction.

Influence of glenoid wear pattern on glenoid component placement accuracy in shoulder arthroplasty

Background

Accurate glenoid component placement in shoulder arthroplasty is often difficult even with the use of preoperative planning. Computer navigation and patient-specific guides increase component placement accuracy, but which patients benefit most is unknown. Our purpose was to assess surgeons' accuracy in placing a glenoid component in vivo using 3-dimensional preoperative planning and standard instruments among various glenoid wear patterns.

Methods

We conducted a retrospective review of 170 primary anatomic total shoulder arthroplasty (aTSA) and reverse total shoulder arthroplasty (rTSA) performed at a single institution. Commercially available preoperative planning software was used in all arthroplasties with multiplanar 2-dimensional computed tomography and a 3-dimensional implant overlay. After registration of intraoperative bony landmarks to the navigation system, participating surgeons with knowledge of the preoperative plan were blinded to the computer screen and attempted to implement their preoperative plan by simulating placement of a central-axis glenoid guide pin. Two hundred thirty-three screenshots of surgeon's simulated guide pin placement were included. Glenoid displacement, error in version and inclination, and overall malposition from the preoperatively planned target point were stratified by posterior wear status (with [Walch B2 or B3] or without [A1, A2, or B1]) and Walch classification (A1, A2, B1, B2, or B3). The glenoid component was considered malpositioned when version or inclination errors exceeded 10° or the starting point displacement exceeded 4 mm.

Results

For rTSA, errors in version were greater for glenoids with posterior wear compared with those without (8.1° ± 5.6° vs. 4.7° ± 4.0°; P < .001). On post hoc analysis, B2 glenoids had greater version error than A1, A2, and B1 glenoids. A greater proportion of glenoids undergoing rTSA that possessed posterior wear had an error in version >10° compared with those without (31% vs. 8%; P < .001). Consequently, glenoids undergoing rTSA with posterior wear were malpositioned at a greater rate compared with those without (73% vs. 53%). In contrast, glenoids undergoing aTSA with and without posterior wear did not differ based on displacement error, version error, inclination error, or malposition occurrence.

Conclusions

Posterior glenoid bone loss more commonly resulted in glenoid version errors exceeding 10 degrees and component malposition in rTSA, but not for aTSA. Malposition was still relatively high in patients without significant posterior wear for both aTSA (36%) and rTSA (53%). Surgeons should consider alternate techniques beyond preoperative planning and standard instrumentation when performing shoulder arthroplasty in patients with posteriorly worn glenoids.

Pedal Musculovenous Pump Activation Effectively Counteracts Negative Impact of Knee Flexion on Human Popliteal Venous Flow

Knee scooters are commonly used for mobility instead of other devices. However, passive popliteal venous flow impedance has been observed with knee scooter usage ostensibly as a result of deep knee flexion. This study aimed to characterize the magnitude of impact knee flexion has on popliteal venous flow in relation to the degree of knee flexion when walking boot immobilized. Furthermore, the countervailing effect of standardized pedal musculovenous pump (PMP) activation was observed. Popliteal venous diameter and flow metrics were assessed with venous ultrasonography in 24 healthy individuals. Straight leg, crutch, and knee scooter positioning while wearing a walking boot and non-weight-bearing were compared. Flow was assessed with muscles at rest and with PMP activation. Of 24 participants, 16 (67%) were female. Twelve limbs (50%) were right sided. The mean age was 21.9 (SD = 3.0) years, and the mean body mass index was 21.9 (SD 1.9) kg/m². Observer consistencies were excellent (intraclass correlation range = 0.93 to 0.99). No significant differences in mean vessel diameter, time-averaged mean velocity, and total volume flow occurred (all P > .01). Corresponding knee flexion effect sizes were small (range = -0.04 to -0.26). A significant decrease (-24%) in active median time-averaged peak velocity occurred between upright and crutch positions (20.89 vs 15.92 cm/s; P < .001) with a medium effect size (-0.51). PMP activation increased all flow parameters (all P < .001), and effect sizes were comparatively larger (>0.6) across all knee flexion positions.Clinical Significance: Knee flexion has a small to medium impact on popliteal venous return in healthy patients. Active toe motion effectively counters the negative effects of gravity and knee flexion when the ankle is immobilized.Levels of Evidence: Therapeutic, Level IV.

Organometallic supramolecular chemistry with monosaccharides: triethylammonium mu-chloro-bis[chloro(eta5-cyclopentadienyl)-(methyl 4,6-o-benzylidene-beta-D-glucopyranosidato-1kappaO2,1:2kappaO3) zirconate]

The reaction of [CpZrCl3(thf)2] with methyl 4,6-O-benzylidene-beta-D-glucopyranoside (beta-MeBGH2, 1) in the presence of Et3N results in the formation of the zirconate complex [Et3NH] [(CpZrCl)2(mu-Cl) (mu-(beta-MeBG)]2] (2). X-ray structure analyses were performed from the ligand precursor beta-MeBGH2 1 as well as from 2. Compound 1 crystallizes in the monoclinic chiral space group P2(1). The molecules show a flat arrangement including the benzylidene protecting group, and are packed in columns. The columns are held together in pairs by the formation of hydrogen bonds between the hydroxy functions in positions 2 and 3. Compound 2 crystallizes in the orthorhombic space group P2(1)2(1)2(1). The beta-MeBG ligands are chelating the Zr atoms through the oxygen atoms in positions 2 and 3 of the glucopyranosidato ligand revealing a 1-zircona-2,5-dioxolane moiety each; the oxygen atom in position 3 is linked to both of the Zr atoms. Additionally one chloro ligand is bridging the two Zr centers. Two terminally bound chloro ligands stick out from the two Zr atoms into a chiral U-shaped cavity constructed by the two beta-MeBG ligands. The cavity incorporates the tertiary ammonium cation [Et3NH]+ which is bound to one of the terminal chloro ligands through a hydrogen bond. The inclusion of the [Et3NH]+ cation in the U-shaped cavity, even in solution, is demonstrated by NMR spectroscopic data.

Characterisation of coupling products formed by biotransformation of biphenyl and diphenyl ether by the white rot fungus Pycnoporus cinnabarinus

Cells of the white rot fungus Pycnoporus cinnabarinus grown in glucose were able to hydroxylate biphenyl and diphenyl ether, although growth was inhibited by these substrates at concentrations above 250 microM. 2- and 4-Hydroxybiphenyl were detected as products of biphenyl metabolism and 2- and 4-hydroxydiphenyl ether as products of diphenyl ether metabolism in the culture media. After addition of 2-hydroxydiphenyl ether and 2-hydroxybiphenyl to cell-free supernatants containing laccase as the only ligninolytic enzyme, different coloured precipitates were formed. HPLC analysis revealed the formation of additional hydrophobic metabolites with one major product per transformation. Mass spectrometric analysis of the methyl derivatives of the polymer mixture indicated dimers and trimers with different binding types. The main products were identified as dimers with carbon-carbon bonds in para-position to the hydroxyl group of the monomers by mass spectroscopy and nuclear magnetic resonance spectroscopy.

A "Double-Diamond Superlattice" Built Up of Cd17S4(SCH2CH2OH)26 Clusters

A simple preparation of Cd(17)S(4)(SCH(2)CH(2)OH)(26) clusters in aqueous solution leads to the formation of colorless blocky crystals. X-ray structure determinations revealed a superlattice framework built up of covalently linked clusters. This superlattice is best described as two enlarged and interlaced diamond or zinc blende lattices. Because both the superlattice and the clusters display the same structural features, the crystal structure resembles the self-similarities known from fractal geometry. The optical spectrum of the cluster solution displays a sharp transition around 290 nanometers with a large absorption coefficient ( approximately 84,000 per molar per centimeter).