Correction of bilateral congenital swan-neck deformity by use of Mitek mini anchor: a new technique

Effect of a Flexor Digitorum Superficialis Hemitenodesis on Reducing Volar Plate Strains for Swan Neck Deformities

BACKGROUND

Flexor digitorum superficialis (FDS) hemitenodesis is a common procedure to treat swan neck deformity (SND). We hypothesize that this surgical technique is a biomechanically effective way to reduce strain in the volar plate at the proximal interphalangeal joint (PIPJ).

METHODS

Fifteen digits from 5 cadaveric specimens were tested using a novel in vitro active finger motion simulator under 4 finger conditions: intact, SND, FDS hemitenodesis, and FDS hemitenodesis with distal interphalangeal (DIP) joint fusion. Tensile loads in FDS and flexor digitorum profundus (FDP) and joint ranges of motion were measured by electromagnetic tracking. In addition, strain gauges were inserted under the volar plate to measure strain during PIPJ hyperextension. Results were analyzed using 1-way repeated-measures analysis of variance tests.

RESULTS

The SND condition increased volar plate strain by 176% ± 25% (P < .001) compared with the intact condition. The FDS hemitenodesis repair relieved more than 50% of the SND strain, restoring it to within no statistical difference from intact. The DIP fusion further reduced strain with no further statistical significance. At full flexion, FDS and FDP tendon loads diverged as a function of the test condition (P < .001). With the FDS hemitenodesis, the FDP load increased by 2.1 ± 1.5 N from the SND condition (P < .001), whereas the FDS load decreased by 1.3 ± 1.3 N (P = .012).

CONCLUSION

The FDS hemitenodesis repair restored strains to within 3.0 milli-strain of the intact condition with no significant difference. Application of DIP fusion did not further protect the PIPJ from increased hyperextension and further exacerbated the imbalance of flexor tendon loads.

A porous swelling copolymeric material for improved implant fixation to bone

Most metallic commercial bone anchors, such as screws and suture anchors achieve their fixation to bone through shear of the bone located between the threads. They have several deficiencies, potentially leading to failure, which are particularly evident in low-density bone. These include stress-shielding resulting from mechanical properties mismatch; lack of mechanically induced remodeling and osteointegration; and when the pullout force on the anchor, during functional activities, exceeds their pullout strength, catastrophic failure occurs leaving behind large bone defects that may be hard to repair. To overcome these deficiencies, we introduced in this study a porous swelling co-polymeric material and studied its swelling and compressive mechanical characteristics as bone anchor under different configurations. Porosity was achieved by adding a non-dissolvable agent (NaCl) during the process of polymerization, which was later dissolved in water, leaving behind a porous structure with adequate porosity for osteointegration. Three different groups of cylindrical samples of the swelling co-polymer were investigated. Solid, fully porous, and partially porous with a solid core and a porous outer layer. The results of the swelling and simple compression study show that the partially porous swelling co-polymer maintains excellent mechanical properties matching those of cancellous bone, quick swelling response, and an adequate porous outer layer for mechanically induced osteointegration. These suggest that this material may present an effective alternative to conventional bone anchors particularly in low-density bone.

A novel surgical correction and innovative splint for swan neck deformity in hypermobility syndrome

Splinting is a great domain of occupational therapy profession. Making a splint for the patient would depend on the need or requirement of the problems and deformities. Swan neck deformity is an uncommon condition, and it can be seen in rheumatoid arthritis, cerebral palsy, and after trauma. Conservative treatment of the swan neck deformity is available by different static splints only. There are very few reports of surgical correction of swan-neck deformity in benign hypermobility syndrome. This case report describes the result of novel surgical intervention and an innovative hand splint in a 20-year-old female with a history of cardiovascular stroke with no residual neurological deficit. She presented with correctable swan neck deformity and failed to improve with static ring splints to correct the deformity. She underwent volar plate plication of the proximal interphalangeal joint of the left ring finger along with hemitenodesis of ulnar slip of flexor digitorum superficialis (FDS) tendon whereby, the ulnar slip of FDS was passed through a small surgically created rent in A2 pulley and sutured back to itself. Postoperatively, the patient was referred to occupational therapy for splinting with the instruction that the splint would work sometimes for as static and some time as dynamic for positional and correction of the finger. After occupational therapy intervention and splinting, the patient had a full correction of the swan-neck deformity with near full flexion of the operated finger and can work independently.

Volar Tenodesis for the Treatment of Swan-neck Deformity; A Systematic Review

BACKGROUND

Swan-neck deformity is a common problem particularly in patients with Rheumatoid arthritis. Mobile swan-neck deformities (Nalebuff types I,II) can be treated non-operatively and operatively. In this paper we report on a systematic review of the treatment of swan-neck deformities with volar tenodesis.

METHODS

We performed a literature search and analysed the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Only eight papers were eligible. None was of high quality. The data reporting was very variable. Therefore, no meta-analysis could be performed, but only a descriptive analysis.

RESULTS

The techniques work in preventing proximal inter-phalangeal joint hyperextension between 60 and 100% in these studies. There appears to be some recurrence of hyper-extension with time so that papers with longer follow-up tend to have poorer results.

CONCLUSIONS

There is no good evidence that one technique is superior to another. The choice of technique is likely to remain based on surgeon preference for the foreseeable future. Future studies should be at least comparative and preferably part of a trial.

"Swan neck deformity" of the second toe corrected by flexor digitorum longus to flexor digitorum brevis tenodesis

"Swan neck deformity" of the second toe is a rare deformity. It is a hyperextension of the proximal interphalangeal joint. The patient may complain of painful callosity underneath the proximal interphalangeal joint. Surgical correction should be considered if conservative treatment fails to relieve the pressure point. The optimal surgical option for this deformity has not yet been defined. We report a case of swan neck deformity of the second toe that was successfully corrected by flexor digitorum longus to brevis tenodesis.

LEVELS OF EVIDENCE

Therapeutic Level IV: Case Report.

SURGICAL REPAIR OF CENTRAL SLIP AVULSION INJURIES WITH MITEK BONE ANCHOR — RETROSPECTIVE ANALYSIS OF A CASE SERIES

The purpose of this study is to describe our technique of central slip repair using the Mitek bone anchor and to evaluate the treatment outcome. Eight digits in eight patients were reconstructed using the bone anchor: three little fingers, two middle fingers, two index fingers and one ring finger. There were two immediate and six delayed repairs (range from one day to eight months). Four patients had pre-operative intensive splinting and physiotherapy to restore passive extension of the proximal interphalangeal joint prior to central slip reconstruction. All patients have made good progress since surgery. No patient requires a second procedure and none of the bone anchors have dislodged or loosened. We conclude that the Mitek bone anchor is a reliable technique to achieve soft tissue to bone fixation in central slip avulsion injuries. We recommend that this technique be considered as a treatment option for patients requiring surgical repair.

Modified kinematic technique for measuring pathological hyperextension and hypermobility of the interphalangeal joints

Dynamic finger joint motion is difficult to measure using optical motion analysis techniques due to the limited surface area allowed for adequate marker placement. This paper describes an extension of a previously validated kinematic measurement technique using a reduced surface marker set and outlines the required calculations based on a specific surface marker placement to calculate flexion/extension and hyperextension of the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints. The modified technique has been assessed for accuracy using a series of static reference frames (absolute residual error = ±3.7°, cross correlation between new method and reference frames; r=0.99). The method was then applied to a small group of participants with rheumatoid arthritis (seven females, one male; mean age = 62.8 years ± 12.04) and illustrated congruent strategies of movement for a participant and a large range of finger joint movement over the sample (5.8-71.1°, smallest to largest active range of motion). This method used alongside the previous paper provides a comprehensive, validated method for calculating 3-D wrist, hand, fingers, and thumb kinematics to date and provides a valuable measurement tool for clinical research.

Long-term results of lateral band translocation for the correction of swan neck deformity in cerebral palsy

PURPOSE

The aim of this study was to evaluate the long-term effect of lateral band translocation for correcting swan neck deformity in patients with cerebral palsy at a minimum follow-up of 5 years.

METHODS

Swan neck deformities of 62 fingers were corrected using a modified lateral band translocation. At 1-year and 5-year follow-up, any recurrence of hyperextension was recorded through nonconstrained evaluation. Active extension of the proximal interphalangeal joint beyond 0 degree was considered a recurrence.

RESULTS

Correction was successful for 84% of the operated fingers at 1-year follow-up. After 5 years, the success rate had decreased to 60%. Furthermore, no relationship was found between any of the concomitant surgical procedures and the number of patients with recurrences.

CONCLUSIONS

The long-term result of lateral band translocation is disappointing in our series, and it should not be advocated as a procedure with long-lasting success in patients with cerebral palsy.

Congenital swan neck deformity of fingers with syndactyly

Congenital swan neck deformity of the fingers is an uncommon congenital disorder. It is sporadic and not associated with other malformations. We report a case of congenital swan neck deformity of the fingers in a 16-year-old boy, with associated ulnar deviation of the fingers, bilateral simian creases and soft tissue syndactyly.