Influence of the biomechanical evaluation of rupture using two shapes of same intramedullary implant after proximal interphalangeal joint arthrodesis to correct the claw/hammer pathology: A finite element study.

We used finite element analysis to study the mechanical stress distribution of a new intramedullary implant used for proximal interphalangeal joint (PIPJ) arthrodesis (PIPJA) to surgically correct the claw-hammer toe deformity that affects 20% of the population. After geometric reconstruction of the foot skeleton from claw toe images of a 36-year-old male patient, two implants were positioned, in the virtual model, one neutral implant (NI) and another one 10° angled (10°AI) within the PIPJ of the second through fourth HT during the toe-off phase of gait and results were compared to those derived for the non-surgical foot (NSF). A PIPJA was performed on the second toe using a NI reduced tensile stress at the proximal phalanx (PP) (45.83 MPa) compared to the NSF (59.44 MPa; p < 0.001). When using the 10°AI, the tensile stress was much higher at PP and middle phalanges (MP) of the same toe, measuring 147.58 and 160.58 MPa, respectively, versus 59.44 and 74.95 MPa at corresponding joints in the NSF (all p < 0.001). Similar results were found for compressive stresses. The NI reduced compressive stress at the second PP (-65.12 MPa) compared to the NSF (-113.23 MPa) and the 10°AI (-142 MPa) (all p < 0.001). The von Mises stresses within the implant were also significantly lower when using NI versus 10°AI (p < 0.001). Therefore, we do not recommend performing a PIPJA using the 10°AI due to the increase in stress concentration primarily at the second PP and MP, which could promote implant breakage.

Ideal implant choice for proximal interphalangeal joint arthrodesis in hammer toe/claw toe deformity correction: A systematic review.

Intramedullary devices have been developed to reduce the problems associated with Kirschner (K)-wire fixation in proximal interphalangeal joint (PIPJ) arthrodesis. The purpose of this systematic review is to compare the surgical outcomes of K-wires versus novel internal fixation devices in PIPJ arthrodesis in claw/hammer toe surgery. The databases searched were PubMed, Scopus, Cochrane, and Embase with keywords "claw toe OR hammer toe" AND "proximal interphalangeal OR PIP" AND "fusion OR arthrodesis." Clinical trials published in English with evidence levels I, II, and III were included. Five studies, including one randomized controlled trial and four case-controlled studies, were identified to meet the inclusion criteria. Overall, the studies showed promising results in union rates using the novel internal devices compared to K-wires. However, the novel internal devices seem not to present advantages in clinical parameters such as pain levels, patient satisfaction, foot-related function, or surgical complication rates.

Comparison of Percutaneous Reduction and Pin Fixation in Acute and Chronic Pediatric Mallet Fractures.

BACKGROUND: Although pediatric mallet fractures are more common than adult fractures, no techniques have focused on surgical fixation of pediatric mallet fractures. This study aims to describe the technique and results of percutaneous reduction and fixation in acute and chronic pediatric mallet fractures. METHODS: This is a retrospective review of 51 pediatric mallet fractures treated with percutaneous wire fixation from 2007 to 2014; 38 were acute fractures and 13 were chronic (>4 wk from injury). Surgical technique was identical for all fractures: (1) levering the dorsal fragment into its anatomical bed with a percutaneous towel clip; (2) percutanously transfixing the distal interphalangeal joint in slight hyperextension; (3) placing 2 percutaneous kirschner wires, 1 radial and 1 ulnar, from the dorsal epiphyseal fragment to the volar metaphyseal cortex. Outcomes were defined by the Crawford classification. RESULTS: Average age was 14.6 years (range, 11 to 18 y). Mean time from injury to surgery was 16.2 days in the acute group and 50.8 days in the chronic group. Mean joint surface involvement was 50.8% of the articular base with a mean of 2.0 mm of articular gap (acute fractures 1.9 mm, chronic fractures 2.5 mm, P=0.017). Average preoperative extensor lag was 24.6 degrees. Average operative time was 31 minutes for acute fractures and 40 minutes for chronic fractures. Mean length of follow-up was 78.5 days. At final follow-up, all patients healed with an articular gap of 0.2 mm in the acute group and 0.6 mm in the chronic group (P=0.037) with no nonunions or volar subluxations. All patients but 8 (5 acute, 3 chronic) achieved full extension with an average extensor lag of 1.1 degree for the entire cohort. No patient had >10-degree extensor lag at final follow-up. All patients achieved full active flexion of 90 degrees at final follow-up. In the acute group, the Crawford classification was excellent in 87% (33/38), good in 13% (5/38). In the chronic group, results were excellent in 77% (10/13), good in 23% (3/13) (P>0.05). There were no fair or poor outcomes in either group. A clinical dorsal bump was noted in 18% of patients (22% in the acute group, 15% in the chronic group, P>0.05). There were no infections, wire breakages, nail deformities, or unplanned returns to surgery. CONCLUSIONS: This percutaneous surgical technique to treat pediatric mallet fractures achieves favorable clinical and radiographic results with minimal complications, even in chronic fractures. Results are better than reported for adult mallet fractures. LEVEL OF EVIDENCE: Level II.

Proximal Interphalangeal Arthrodesis of Lesser Toes Utilizing K-Wires Versus Expanding Implants: Comparative Biomechanical Cadaveric Study.

BACKGROUND:: Lesser toe proximal interphalangeal (PIP) joint arthrodesis is one of the most common foot and ankle elective procedures often using K-wires for fixation. K-wire associated complications led to development of intramedullary fixation devices. We hypothesized that X Fuse (Stryker) and Smart Toe (Stryker) would provide stronger and stiffer fixation than K-wire fixation. METHODS:: 12 cadaveric second toe pairs were used. In one group, K-wires stabilized 6 PIP joints, and 6 contralateral PIP joints were fixed with X Fuse. A second group used K-wires to stabilize 6 PIP joints, and 6 contralateral PIP joints were fixed with Smart Toe. Specimens were loaded cyclically with extension bending using 2-N step increases (10 cycles per step). Load to failure and initial stiffness were assessed. Statistical analysis used paired t tests. RESULTS:: K-wire average failure force, 91.0 N (SD 28.3), was significantly greater than X Fuse, 63.3 N (SD 12.9) ( P < .01). K-wire average failure force, 102.3 N (SD 17.7), was also significantly greater than Smart Toe, 53.3 N (SD 18.7) ( P < .01). K-wire initial stiffness 21.3 N/mm (SD 5.7) was greater than Smart Toe 14.4 N/mm (SD 9.3) ( P = .02). K-wire failure resulted from bending of K-wire or breaching cortical bone. X Fuse typically failed by implant pullout. Smart Toe failure resulted from breaching cortical bone. CONCLUSION:: K-wires may provide stiffer and stronger constructs in extension bending than the X Fuse or Smart Toe system. This cadaver study assessed stability of the fusion site at time zero after surgery. CLINICAL RELEVANCE:: Our findings provide new data supporting biomechanical stability of K-wires for lesser toe PIP arthrodesis, at least in this clinically relevant mode of cyclic loading.

Comparative Study of Intramedullary Hammertoe Fixation.

BACKGROUND: Temporary Kirschner wire fixation (K-wire) is a widely used, low-cost fixation method for the correction of hammertoe deformity. Reported complications associated with K-wires prompted the development of new implants over the past decade. However, there is a lack of literature on comparative studies analyzing functional outcomes using validated questionnaires. The purpose of this study was to analyze functional outcomes in patients who had undergone proximal interphalangeal joint fusion using 2 types of intramedullary implant, the Smart Toe and the TenFuse, and to compare them with the outcomes in patients treated with standard K-wire fixation. METHODS: A retrospective review of operative hammertoe correction by a single surgeon was performed in 96 patients followed for more than 12 months. Functional outcome was assessed using the Foot Function Index (FFI), the Short Form 36 (SF-36), and the 10-point visual analog scale (VAS) validated questionnaires. Complications and fusion rates were also evaluated. Several patients in the study underwent corrections in different toes; thus, a total of 186 toes were included in the study. From these, 65 toes (34.9%) were treated with K-wire fixation, 94 (50.5%) with Smart Toe titanium implant, and 27 (14.5%) with TenFuse allograft implant. RESULTS: No statistically significant differences in functional outcome and incidence of complications were observed among the 3 fixation groups, although the 2 intramedullary implants were associated with greater fusion rates and patient satisfaction. Breakage of the Smart Toe implant was significantly higher than that of the other fixations, with 10.6% of implants breaking within the first year postoperatively. SF-36 and VAS scores decreased 12 months after surgery for the 3 types of fixation, with no statistically significant differences observed. CONCLUSION: The use of Smart Toe and TenFuse implants provided operative outcomes comparable to those obtained using a K-wire fixation and slightly better patient satisfaction. Our results suggest that utilization of these implants for hammertoe correction was a reasonable choice that provided good alignment, pain reduction, and improved function at final follow-up. However, they are more expensive than K-wires. For this reason, in-depth cost-benefit studies would be required to justify their use as a standard treatment. LEVEL OF EVIDENCE: Level III, comparative series.

A modified technique for flexor-to-extensor tendon transfer to correct residual metatarsophalangeal extension in the treatment of hammertoes.

A variety of surgical procedures exist for the correction of hammertoe deformities, and several different methods of flexor tendon transfer have been described for the correction of hammertoes associated with extension contracture of the corresponding metatarsophalangeal joint. In the present report, we have described a variation of flexor tendon tenodesis we have found useful.

Hallux claw toe.

Claw hallux is a deformity of the great toe attributed to muscular imbalance. This article describes diagnosis and treatment of this condition. Particular attention is given to surgical techniques such as Jones technique and modified Jones technique.

[Pedobarographic results of Girdlestone-Taylor tendon transfer in flexible small toe deformity]. / Ergebnisse der pedobarographischen Untersuchung nach Girdlestone-Taylor-Sehnentransfer bei flexibler Kleinzehdeformität.

AIM: The aim of the study was to analyze the biomechanical effects of flexible claw toe correction by tendon transfer with the Girdlestone-Taylor approach using dynamic pedobarography. MATERIAL AND METHODS: In the study 12 patients were examined preoperatively and 12 months postoperatively. The results obtained by pedobarography 12 months postoperatively were compared with those of a healthy control group of matched age and body mass index (BMI). For clinical evaluation the American Orthopaedic Foot and Ankle Society (AOFAS) score and visual analogue pain scale (VAS) were evaluated. RESULTS: The results showed a significant increase in the average AOFAS score from 72 (range 63-79) preoperatively to 92 (84-96) points 12 months postoperatively. The pedobarography revealed significantly increased values in the force-time integral and the maximum force for the second and third toes 12 months postoperatively. Compared with preoperative measurement values a significantly increased peak pressure could be assessed for the third toe only. It is assumed that the combination of functional arthrodesis of the proximal interphalangeal (PIP) joint and the strain shift by tendon transfer causes this increase in peak pressure. CONCLUSION: Atter Girdlestone-Taylor tendon transfer reestablishment of floor contact of flexible claw toes could be demonstrated by dynamic pedobarography.

Foot disorders, foot posture, and foot function: the Framingham foot study.

INTRODUCTION: Foot disorders are common among older adults and may lead to outcomes such as falls and functional limitation. However, the associations of foot posture and foot function to specific foot disorders at the population level remain poorly understood. The purpose of this study was to assess the relation between specific foot disorders, foot posture, and foot function. METHODS: Participants were from the population-based Framingham Foot Study. Quintiles of the modified arch index and center of pressure excursion index from plantar pressure scans were used to create foot posture and function subgroups. Adjusted odds ratios of having each specific disorder were calculated for foot posture and function subgroups relative to a referent 3 quintiles. RESULTS: Pes planus foot posture was associated with increased odds of hammer toes and overlapping toes. Cavus foot posture was not associated with the foot disorders evaluated. Odds of having hallux valgus and overlapping toes were significantly increased in those with pronated foot function, while odds of hallux valgus and hallux rigidus were significantly decreased in those with supinated function. CONCLUSIONS: Foot posture and foot function were associated with the presence of specific foot disorders.

Stress at the second metatarsal bone after correction of hammertoe and claw toe deformity: a finite element analysis using an anatomical model.

BACKGROUND: We used finite element analysis to evaluate three techniques for the correction of hammertoe and claw toe deformities: flexor digitorum longus tendon transfer (FDLT), flexor digitorum brevis tendon transfer (FDBT), and proximal interphalangeal joint arthrodesis (PIPJA). METHODS: We performed a finite element analysis of FDLT and FDBT compared with PIPJA of the second toe using multislice computed tomography and 93 tomographic images of the foot obtained in a healthy 36-year-old man. RESULTS: The PIPJA showed a significantly higher increase in traction and compressive stresses and strain at the medial aspect of the shaft of the second metatarsal bone compared with FDLT or FDBT (P < .01). Mean ± SD compressive stresses increased to -4.35 ± 7.05 MPa compared with the nonsurgical foot (-3.10 ± 4.90 MPa). It can, therefore, be hypothesized that if PIPJA is used to correct the hammertoe and claw toe deformities, it could also increase traction and compressive stresses and strain in the metatarsals during running and other vigorous activities. CONCLUSIONS: There is a biomechanical advantage to performing FDLT or FDBT instead of PIPJA to surgically treat a hammertoe or claw toe deformity. In addition, tensile strain at the dorsal aspect of the second metatarsal bone when performing PIPJA increases the risk of metatarsalgia or stress fracture in patients at risk.

Using a bone allograft to fixate proximal interphalangeal joint arthrodesis.

UNLABELLED: Digital contractures are a very common deformity of the foot and ankle that require surgical correction. It has been shown that arthrodesis provides a better long-term result than arthroplasty of the interphalangeal joints. Arthroplasties usually require K-wire fixation that presents potential complications, such as pin tract infection. This study presents a new cadaveric bone matrix allograft to be used as rigid internal fixation for proximal interphalangeal joint arthrodesis. The purpose of using the allograft as a fixation device is to achieve solid bone fusion and avoid the potential complications of external pin fixation. Arthrodesis of the proximal interphalangeal joint was performed on 63 toes in 32 patients using TenFUSE (Solana Surgical, Memphis, TN), a sterile bone matrix allograft. The authors found 97% fusion rate with no complications reported to this date. It was concluded that this bone matrix allograft provides excellent results and is a suitable alternative fixation device for correction of hammer toe deformity. LEVEL OF EVIDENCE: Level V.

Finite element analysis of the foot: model validation and comparison between two common treatments of the clawed hallux deformity.

BACKGROUND: Clawed hallux is defined by first metatarsophalangeal joint extension and first interphalangeal joint flexion; it can increase plantar pressures and ulceration risk. We investigated two corrective surgical techniques, the modified Jones and flexor hallucis longus tendon transfer. METHODS: A finite element foot model was modified to generate muscle overpulls, including extensor hallucis longus, flexor hallucis longus and peroneus longus. Both corrective procedures were simulated, predicting joint angle and plantar pressure changes. FINDINGS: The clawed hallux deformity was generated by overpulling: 1) extensor hallucis longus, 2) peroneus longus + extensor hallucis longus, 3) extensor hallucis longus + flexor hallucis longus and 4) all three together. The modified Jones reduced metatarsophalangeal joint angles, but acceptable hallux pressure was found only when there was no flexor hallucis longus overpull. The flexor hallucis longus tendon transfer reduced deformity at the metatarsophalangeal and interphalangeal joints but may extended the hallux due to the unopposed extensor hallucis longus. Additionally, metatarsal head pressure increased with overpulling of the extensor hallucis longus + flexor hallucis longus, and all three muscles together. INTERPRETATION: The modified Jones was effective in correcting clawed hallux deformity involving extensor hallucis longus overpull without flexor hallucis longus overpull. The flexor hallucis longus tendon transfer was effective in correcting clawed hallux deformity resulting from the combined overpull of both extensor and flexor hallucis longus, but not with isolated extensor hallucis longus overpull. An additional procedure to reduce the metatarsal head pressure may be required concomitant to the flexor hallucis longus tendon transfer. However this procedure avoids interphalangeal joint fusion.

Lesser toe deformities.

Lesser toe deformities are caused by alterations in normal anatomy that create an imbalance between the intrinsic and extrinsic muscles. Causes include improper shoe wear, trauma, genetics, inflammatory arthritis, and neuromuscular and metabolic diseases. Typical deformities include mallet toe, hammer toe, claw toe, curly toe, and crossover toe. Abnormalities associated with the metatarsophalangeal (MTP) joints include hallux valgus of the first MTP joint and instability of the lesser MTP joints, especially the second toe. Midfoot and hindfoot deformities (eg, cavus foot, varus hindfoot, valgus hindfoot with forefoot pronation) may be present, as well. Nonsurgical management focuses on relieving pressure and correcting deformity with various appliances. Surgical management is reserved for patients who fail nonsurgical treatment. Options include soft-tissue correction (eg, tendon transfer) as well as bony procedures (eg, joint resection, fusion, metatarsal shortening), or a combination of techniques.

Modified plantar plate tenodesis for correction of claw toe deformity.

BACKGROUND: The purpose of the study was to evaluate the efficacy and safety of the modified plantar plate tenodesis for correction of claw toe deformity. MATERIALS AND METHODS: Modified plantar plate tenodesis was performed in ten fresh frozen cadaveric feet with claw toe deformity of the second toe. The plantar plate of the second metatarsophalangeal joint was anchored to the extensor digitorum longus tendon by a figure-of-eight suture. The figure-of-eight construct and the relationship of the digital nerve and the suture were studied. A clinical study was conducted to study the operative times, degree of correction and the improvement of AOFAS score between groups with the original plantar plate tenodesis (Group 1) and modified technique (Group 2). Any neural injury if present was also noted. RESULT: In the cadaveric study, the claw toe deformity was corrected and no nerve injury occurred in any specimen. There was flexor tendon tethering by the suture in 2 specimens. In the clinical study, the average operative time was 51 minutes for Group 1 and 31 minutes for Group 2. The improvement in AOFAS score averaged 44 in Group 1 and 43 in Group 2. The corrective power of the sagittal plane deformity at the metatarsophalangeal joint averaged 25 degrees in Group 1 and 23 degrees in Group 2. CONCLUSION: Plantar plate tenodesis was effective in correction of flexible claw second toe deformity by stabilization of the attenuated plantar plate. The modified technique allowed easier retrieval of the suture and shorter operative time. However, it may result in tethering of the flexor tendon.

A modified Jones procedure for managing clawing of lesser toes in pes cavus: long-term follow-up in 8 patients.

UNLABELLED: Pes cavus is a complex foot deformity in which surgical correction remains challenging. We treated lesser-toe clawing in 11 feet of 8 patients (5 women, 1 bilateral; 3 men, 2 bilateral) with a modified Jones procedure and assessed long-term functional outcomes. We reviewed case notes and completed the Bristol Foot Score, the modified American Orthopaedic Foot & Ankle Society Midfoot Score, and a patient satisfaction questionnaire by means of telephone interviews. Mean age of the patients at the time of surgery was 30 years (range, 10-58 years). Mean time from surgery to the last clinical follow-up was 7 years (range, 0.5-17 years), and mean time from surgery to the telephone interview was 9 years (range, 1-18 years). At the final clinical review, all 11 feet were improved, although 6 had minor complications. The mean Bristol Foot Score was 27 (range, 16-55), and the mean modified American Orthopaedic Foot & Ankle Society Midfoot Score was 76 (range, 47-90), indicative of excellent results. Half of the patients had mild persistent foot pain, but all were satisfied with the outcome. Based on our experience with this group of patients, the modified Jones procedure yields satisfactory correction of lesser toe clawing in patients with flexible pes cavus. LEVEL OF CLINICAL EVIDENCE: 4.