Extension Block Research Articles

Mallet Fractures with Long Fragment Had Poor Outcomes on Extension Block Pinning

Background: Although extension block pinning for mallet fracture is popular, it occasionally results in poor outcome. We reviewed previous cases to elucidate the factors associated with poor outcome. Methods: From 2012 to 2017, 50 mallet fingers in 50 patients were consecutively repaired by extension block pinning using modified Ishiguro method. Inserted Kirschner-wires (K-wires) were removed at 6 weeks, followed by night splinting in extension. For outcome evaluation, distal interphalangeal (DIP) joint motion was measured and classified as either good or poor. Poor outcome was defined as either > 10° of extension lag or < 40° of active flexion or the presence of DIP joint pain. Associations between outcome and age, affected finger, interval to operation, fragment size (in terms of joint surface and dorsal cortex ratios), and fixation angle were evaluated. Results: 33 fingers (66%) had good outcome and 17 (34%) had poor outcome. Mean age was significantly greater in the poor (50.6 years) than in the good (40.1 years) outcome group (p < 0.05). The dorsal cortex ratio was also significantly larger in the poor than in the good outcome group (p = 0.006), but there was no significant difference between two groups in joint surface ratio. Affected finger, interval to surgery, and fixation angle also did not significantly differ between groups. Conclusions: Fracture fragments with a long dorsal cortex and older age associated with poor outcome following extension block pinning for mallet finger. The dorsal cortex ratio should be evaluated pre-operatively to determine the appropriate treatment method.

Greater than 5-year follow-up of outpatient L4-L5 lumbar interspinous fixation for degenerative spinal stenosis using the INSPAN device.

Lumbar spinal stenosis is treated with decompression directly such as laminectomies and indirectly with an interspinous device through distraction and extension block. Interspinous devices (IPD) have also been used as an adjunct to spinal fusion. However, the design for IPD to treat spinal stenosis does not fixate the spine while the design for spinal fusion is designed to fixate the spine. There is a paucity of data on a single device that has been used for both fusion and stenosis. Authors aim to demonstrate the long-term outcomes of interspinous fixation at L4-5 for degenerative spinal stenosis. We evaluated patients with spinal stenosis and degenerative disc disease who were treated with open decompression and distraction of the spinous processes at L4-L5 using an interspinous device. All patients complained of lower back pain and neurogenic claudication. This is a retrospective review of prospectively collected data (level 3) under an IRB approved study cohort. The charts of patient undergoing lumbar decompression with Interspinous Distraction, Fixation using InSpan device (INSPAN LLC) in an outpatient setting were reviewed with over a 5-year follow-up period. 122 surgical cases of lumbar decompression with interspinous fixation, spanning between the timeframe of September 2011 to October 2016. A total of 56 patients had instrumentation at L4-L5. Total female population was 46%. The median age of the patients included in the population was 50.9±10.7 years with a median BMI of 24.8±11.4 kg/m2. Two-year VAS and ODI showed significant improvement from 8.1±1.2 to 1.5±1.1 and 42.9±14.3 to 14.8±5.1. All surgeries were completed in less than one hour. There was a total of 1 revision case with removal of INSPAN and open hemilaminectomy decompression. Long term results demonstrated improved outcomes in patients who underwent Interspinous distraction decompression in an ambulatory surgery center using the INSPAN IPD at L4-L5 for Degenerative Spinal Stenosis. There was one revision converted to hemilaminectomy. There were no complications or blood transfusions.

Management of intraarticular proximal interphalangeal joint fracture-dislocations and pilon fractures with the Ligamentotaxor® device.

Fracture-dislocation and pilon injuries of the proximal interphalangeal joints (PIPJ) continue to pose significant management challenges. Stable fracture configurations can be treated with extension block splinting or pinning. Unstable fractures usually require open or closed reduction and fixation either directly/internally onto the fracture using Kirschner wires, cerclage wires, screws or miniplates or indirectly/externally by ligamentotaxis using external fixators which can be dynamic or static. Dynamic external fixators, such as Suzuki's pins and rubber traction system, S-Quattro and Hynes/Giddins frame, appear intuitive as they provide axial distraction, which reduces the fracture whilst obviating the need to open the fracture. They also allow immediate active movement whilst maintaining reduction. The Ligamentotaxor® (Arex, Pallaiseau Cedex, France) is a commercially-available dynamic external fixator which has been used at our institution since 2013. This retrospective study assessed the outcomes (interphalangeal joint active range of movement (AROM), QuickDASH score and complications) in 19 patients [mean age of 48.6 (SD 16.2)] whose proximal interphalangeal joint (PIPJ) fracture-dislocations and/or pilon fractures were treated with the Ligamentotaxor®. Injuries were classified according to Seno i.e. (1) volar lip fracture ± dorsal dislocation (2) dorsal lip fracture ± volar dislocation (3) pilon fracture. There were fifteen (79%) pilon/Seno 3, three (16%) Seno 1 and one (5%) Seno 2 fractures. The mean PIPJ AROM was 70.6° (SD 4.48°) for all Seno classes and 70° (SD 5.6°) for the pilon subgroup. The QuickDASH score averaged to 2.65 (SD 0.88). There were two pin-site infections, three pin-site inflammations, one osteomyelitis and two complex regional pain syndrome diagnoses. One patient required arthroplasty after missing several appointments. These results, considering the predominance of pilon fractures, compare favourably the published Ligamentotaxor® and other dynamic external fixator systems.

Mini-Plate and Screw Fixation Technique for Comminuted Flexor Digitorum Profundus Avulsion Fracture

Avulsion fracture of flexor digitorum profundus (FDP) tendon is relatively rare fracture at the distal phalangeal base than avulsion fracture of terminal extensor tendon. Terminal extensor avulsion fracture, known as bony mallet finger, could be successfully treated by closed reduction and pinning, such as extension block technique. However, most of FDP avulsion fracture, known as Jersey’s finger, needed open reduction, because of the proximal migration of fracture fragment and difficulty of pin fixation. Up to date, most of FDP avulsion fractures were treated by open reduction and fixation by pull-out suture or suture anchor technique. We report a case of comminuted FDP avulsion fracture, successfully treated by open reduction and mini-plate and screw fixation technique.

A comparison of single versus double cortical procedure using dorsal Kirschner wire through extension block method in the surgical treatment of mallet finger

Objectives: In this study, we aimed to compare functional and radiological outcomes of single versus double cortical procedure using a Kirschner wire (K-wire) through extension block method (EBM) in the surgical treatment of bony mallet finger. Methods: Between January 2019 and April 2020, a total of 21 patients (13 males, 8 females) who underwent EBM for a bony mallet finger were retrospectively analyzed. The patients were divided into two groups as Group 1 (n=9) and Group 2 (n=12). Surgical treatment was performed using dorsal K-wires through a single cortical line in Group 1 and through a double cortical line in Group 2. Functional outcomes were evaluated using the Crawford’s evaluation criteria. Time to union in the fracture line was compared between the groups. Results: The mean age was 37 (range, 22 to 57) years and the mean follow-up was 11 (range, 8 to 15) months. According to the Crawford’s criteria, the outcomes were excellent in 19 patients and good in two patients. There was no statistically significant difference in the functional outcomes between the groups (p>0.05). Time to complete union was 31 days in Group 1 and 29 days in Group 2 (p=0.06). Radiographic complete union was achieved in both groups. Serous discharge was observed from the entry site of the K-wire in one patient in each group. After one-week oral antibiotherapy, serous discharge resolved. Conclusions: The EBM is an effective and valid method in the treatment of mallet finger, and both the single and double cortical procedures through the dorsal K-wire yield comparable functional and radiographic outcomes.

Extension Block Pinning in Subacute/Late Bony Mallet Finger Injuries

Mallet finger is inability to fully extend a finger due to the disruption of the extensor mechanism integrity at the distal interphalangeal (DIP) joint level. Cases with DIP joint subluxation, and avulsion fractures involving more than 30% of the DIP joint surface are candidates for surgery. Subacute/late cases have poor outcomes. Investigating the success of extension block pinning in subacute/late bony mallet finger cases is aimed. Patient demographics, the rate of DIP joint involvement in plain X-rays, subluxation status of DIP joint, the time between injury and operation, the duration of the operation, complications in post-operative follow-up, extensor lag and healing status of bone were reviewed. Patient outcomes and relation with operative delay and joint subluxation were analyzed. Mean rate of DIP joint involvement of study group was 43.4 ± 6.12%. Half of the study group (n=7) had DIP joint subluxation. Mean time from injury to operation was 29.78±20.4 days. Six patients’ time from injury to operation was longer than 5 weeks. Study group had statistically significant improvement after surgery. Preoperative mean extensor lag was 15.71° ± 7.30° and postoperative mean extensor lag was 5.57° ± 8.89°(p5 weeks) and presence of subluxation did not alter the outcome (p=0.353 and p=0.149, respectively). Extension block pinning technique is a fast, easy-to-apply technique with minimal morbidity. Although it has more limited results in chronic cases, it can be used safely in the majority of cases requiring surgery.

A Flexor Digitorum Superficialis Tenodesis Technique for Surgical Treatment of Finger PIP Joint Volar Plate Chronic Avulsion.

Background: Chronic, post-traumatic, avulsion of the proximal interphalangeal (PIP) joint volar plate represents a disabling lesion. The purpose of this report is to describe a flexor digitorum superficialis (FDS) tenodesis using a mini-bone anchor inserted into the proximal phalanx, and its clinical outcome. Methods: 15 patients with chronic post-traumatic hyperextension instability of the PIP joint were treated surgically. From the first post-operative day patients were invited to start an early gradual joint active motion, wearing an extension block splint. Forty days after surgery, clinical evaluations were carried out, including: joint stability, pain and range of motion (ROM). The use of a circumferential splint was recommended for two further months, avoiding strenuous manual activities. The range of motion, time lost at work and the functional results were recorded six months after surgery. Results: At last follow up, 7 of the 13 reviewed patients presented an excellent functional recovery, with complete resolution of pain and stability with attainment of ROM comparable to the contralateral finger. The others 6 patients obtained good results, with remission of the functional impairment and pain, with either residual hyperextension or flexion contracture. There was one case of recurrence consecutively to a premature traumatic work-related activity. Conclusions: The FDS tenodesis via a bone anchor, combined with early active PIP joint protected motion, was shown in this study to be effective and reliable.

Delayed Extension Block Pinning in 27 Patients With Mallet Fracture.

Background: Untreated bony mallet fingers can cause an array of problems; therefore, adequate treatment is essential. The primary aim of this study was to determine the patient-reported functional outcome of delayed surgical intervention of bony mallet fingers. The secondary aim was to determine the complication rate of delayed surgical intervention. Methods: In this single-center retrospective cohort study, all consecutive patients treated between 2010 and 2016 at our level 2 regional teaching hospital were included. Inclusion criterion was a bony mallet finger injury (excluding the thumb), presenting >21 days after injury, treated with extension block pinning. Indications for surgery were >2 mm fragment displacement or volar subluxation of the distal interphalangeal joint. Six to 82 months postoperatively, patients completed the Patient-Rated Wrist and Hand Evaluation (PRWHE) by phone. Complications were extracted by chart review. Results: Twenty-seven patients were included, and all completed the PRWHE. Median time to surgery was 35 days (interquartile range [IQR] = 29-42; range = 22-61). Reasons for delay in surgical treatment were patient/physician delay in 24 cases and failed conservative treatment in 3 cases. The median PRWHE score was 0 (IQR = 0-5; range = 0-22.5). After retrospective assessment of the outpatient charts, no early symptoms of malunion or nonunion were found. One patient had a loss of Kirschner-wire fixation, which was corrected. Three patients had an infection that required antibiotic treatment. Conclusions: Delayed surgical management of bony mallet fingers demonstrated adequate functional outcome with minimal complications when compared with prior literature.

Unstable Dorsal Fracture-Dislocations of the Proximal Interphalangeal Joint: Volar Plate Fixation with or without Bone Graft.

To evaluate the treatment of severe dorsal fracture dislocation (DFD) injuries of the proximal interphalangeal joint (PIPJ) by open reduction, bone grafting and fixation with mini-hook plates. Fourteen patients with extensive dorsal fracture dislocation of the PIPJ were operatively treated to reconstruct the fractured middle phalanx volar lip using a fabricated hook plate in conjunction with elevation and bone grafting of depressed articular fragments where present. Restoration of PIPJ articular anatomy and congruence by hook plate fixation permitted full-range mobilization of the joint during fracture healing, with an average arc of motion of 81° and an average loss of extension of 12.9° at a minimum of 6 months follow up. Hook plate treatment of PIPJ fracture dislocation restores articular anatomy and joint congruence at a single sitting and permits post-operative mobilization without the need for extension block splinting. Our results demonstrate a good range of motion following treatment, however hardware removal and tenolysis was necessary in 36% of cases.

A Variation-Aware Design Methodology for Distributed Arithmetic

Distributed arithmetic (DA) brings area and power benefits to digital designs relevant to the Internet-of-Things. Therefore, new error resilient techniques for DA computation are urgently required to improve robustness against the process, voltage, and temperature (PVT) variations. This paper proposes a new in-situ timing error prevention technique to mitigate the impact of variations in DA circuits by providing a guardband for significant (most significant bit) computations. This guardband is initially achieved by modifying the sign extension block and carefully gate-sizing. Therefore, least significant bit (LSB) computation can correspond to the critical path, and timing error can be tolerated at the cost of acceptable accuracy loss. Our approach is demonstrated on a 16-tap finite impulse respons (FIR) filter using the 65 nm CMOS process and the simulation results show that this design can still maintain high-accuracy performance without worst case timing margin, and achieve up to &#x0D; &#x0D; &#x0D; &#x0D; 32&#x0D; %&#x0D; &#x0D; &#x0D; &#x0D; power savings by voltage scaling when the worst case margin is considered with only &#x0D; &#x0D; &#x0D; &#x0D; 9&#x0D; %&#x0D; &#x0D; &#x0D; &#x0D; area overhead.

Ténodèse par mini-ancre du flexor digitorum superficialis pour les déformations en hyperextension de l’articulation IPP dans l’arrachement chronique de la plaque palmaire. Technnique originale

As a result of a severe sprain, the avulsion of the volar plate can lead to instability of the PIP joint. This lesion causes a finger hyperextension disabling deformity, which lead to pain and functional restriction. A late diagnosis is not infrequent and the volar plate is usually retracted or thinned, thus a functional repair has to be researched. With this goal Littler conceived a flexor digitorum superficialis tenodesis in 1959. The purpose of this report is to describe a modified Littler's technique for the correction of chronic, traumatic joint hyperextension. 15patients with a diagnosis of chronic post-traumatic hyperextension instability of the PIP joint were treated surgically in three years. The flexor sheath was incised between the A1 and A2 pulleys. The ulnar slip of the FDS was cut as proximally as possible. A minibone anchor was then placed at the centre of the P1 in a slight sidelong proximal-to-distal direction. The FDS slip was sutured to the anchor, carefully tensioning it so that the PIP joint was approximately 5–10° short of full physiological extension. The wound was covered with a slight dressing and a temporary orthoses was applied dorsally, leaving the flexion motion free. Postoperatively patients were invited to start an early gradual finger active motion, wearing an extension block splint. Forty days after surgery, clinical outpatient evaluations were carried on to evaluate joint stability, pain, range of motion. The use of an annular splint was recommended for two further months, avoiding strenuous manual activities. Two patients were lost at follow-up. At six months after surgery, 13 patients were revalued. The range of motion, time lost from work and the functional results were recorded. At last follow up, 7 of the 13 reviewed patients presented an excellent functional recovery, equivalent to complete resolution of the hyperextension and pain, attainment of ROM comparable to the contralateral finger and a stable joint. Others 6 patients obtained as well good results, with remission of the functional impairment and pain, but a residual moderate joint hyperextension or a slight PIP joint flexion contracture was observed. A case of recurrence was recorded, consecutively to a premature traumatic work-related activity. The average time lost from work was equal to 24 days. The FDS tenodesis via a bone anchor combined with early active PIP joint protected motion resulted in this trial to be effective and reliable over time.

Supplemental Method for Reduction of Irreducible Mallet Finger Fractures by the 2–Extension Block Technique: The Dorsal Counterforce Technique

We suggest a method to achieve anatomical reduction in mallet finger fractures that are insufficiently treated by the 2-extension block wire technique. We performed a retrospective review of 18 patients who were found to have an irreducible dorsal fragment and distal interphalangeal joint incongruence owing to rotation of the dorsal fragment in the sagittal plane. In these cases, we additionally employed a dorsal counterforce technique to supplement the 2-extension block technique. An additional K-wire was used to apply counterforce against the distal part of the dorsal fragment and control rotation in the sagittal plane. All 18 fractures united. Congruent joint surfaces and anatomical reduction wereseen in all cases. The mean active flexion of the distal interphalangeal jointswas83.8° (range, 79°-88°) and the mean extension loss was 0.4° (range, 0°-4°). We believe that the dorsal counterforce technique effectively supplements the 2-extension block K-wire technique and aids control of dorsal fragment rotation in the sagittal plane. Therapeutic IV.

Extension block and direct pinning methods for mallet fracture: A comparative study.

BackgroundMallet fracture can easily occur during sports activities or in daily life; however, the principles and methods of treatment for such fractures remain debated. Among the surgical treatments, various methods of closed reduction have been proposed. We treated patients with the extension block method (EBM) and the direct pinning method (DPM), and then compared the results. We assessed differences in range of motion and measurements of finger movement after surgery.MethodsA total of 41 patients who underwent surgery from August 2013 to September 2015 were evaluated retrospectively. Among them, 21 patients were treated with the EBM and 20 patients were treated with the DPM. We then compared extensor lag, range of motion, and outcomes according to Crawford’s criteria between before surgery and at 6 to 8 months postoperatively.ResultsThe postoperative extensor lag improvement was 4.28° and 10.73°, and the postoperative arc of motion was 55.76° and 61.17° in the EBM and DPM groups, respectively. The Crawford assessment showed no statistically significant difference between the groups, although the score in the DPM group was higher than that in the EBM group (3.5 vs. 3.1).ConclusionsAs closed reduction methods for the treatment of mallet fracture, both the EBM and DPM showed good results. However, the DPM proved to be superior to the EBM in that it produced greater improvements in extensor lag and range of motion.

Surgical management of mallet finger with extension block pinning

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Various surgical and nonsurgical treatments have been described in the management of mallet finger. The purpose of this study is to evaluate the effectiveness of extension block pinning in the management of displaced mallet finger fractures.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; We conducted a retrospective study in which extension block pinning was done for displaced Mallet finger fractures. We included 10 patients in our study who were treated between 2016 and 2018. Fractures were classified according to Wehbe and Schnieder’s classification. All the procedures were done using ring block anaesthesia. Postoperative radiographic assessment was done at each follow up at 15 days interval. Wires were removed after radiologic confirmation of fracture healing. Assessment of the outcome was done using Crawford’s criteria.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; According to Wehbe and Schnieder’s classification IIB type was the most common. All fractures involved more than 30% of articular surface. Average operative time was 30 mins. Congruent anatomical reduction was achieved in all the patients (intrarticular step off less than 1 mm). Average healing time of the fractures was 40 days. Seven out of the ten patients had excellent results. No wire related complications were seen in our patients.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; Extensor block pinning when performed accurately is an easy, economical and effective technique in treatment of mallet fingers.&lt;/p&gt;

Derotation of the mallet piece: A crucial point in mallet fracture surgery

Mallet fracture is an avulsion of the extensor tendon and fracture of the dorsal rim of the articular surface of distal phalanx at the same time. If a part of the mallet fracture is angled or rotated to such a degree that prevents full anatomic reduction, malunion and deformities may occur as a result. The objective of this study was to describe a new surgical technique to provide derotation of the mallet fracture. A 22G or 21G needle is used like a joystick to reduce the mallet fracture with small, gentle movements. The extension block pinning technique described by Ishiguro was applied after proper alignment had been achieved. Bony union was achieved for all patients 6 weeks later. Derotation of type 2 and 3 mallet pieces with closed reduction to prevent surgical failure is simple but effective.

Tips Under the Skin: A Simple Modification of Extension Block Pinning for Mallet Fractures.

Pins exposed out of the skin after surgery for mallet fractures keep patients from washing their hands. The authors buried the tips of all pins under the skin while performing extension block pinning for 14 patients with mallet fractures. The patients were allowed to wash their hands 4 to 5 days postoperatively, without any dressing or splinting. The pins were removed at a mean of 8 weeks postoperatively. Solid union was achieved in all 14 fractures. No pull-out or subsidence of the pin was observed. No patient developed infection or other pin-related complications. Mean extension lag at final follow-up was 4°. [Orthopedics. 2018; 41(2):e299-e302.].

A retrospective study of closed extension block pinning for mallet fractures: Analysis of predictors of postoperative range of motion

Extension block pinning is a simple and reliable technique for mallet fractures, but poor results are sometimes obtained. The predictors of postoperative range of motion after extension block pinning of mallet fingers were investigated. The outcomes for postoperative active motion of the distal interphalangeal (DIP) joint, such as flexion angle, extension loss, and total range of motion, were examined. Predictors such as age, gender, finger, fragment size, joint subluxation, the time from injury to operation, procedure, fixation angle, the time from operation to wire removal, and joint step-off were evaluated statistically. With a mean 12.2-month follow-up, according to Crawford's criteria, 49 of 116 fingers (42%) had an excellent result, 37 (32%) had a good result, 29 (25%) had a fair result, and 1 (1%) had a poor result. The mean flexion angle was 62.9 ± 13.2°, extension loss was -6.6 ± 7.3°, and total range of motion was 55.8 ± 17.0° in the DIP joint. Pin tract infections were confirmed in 7 fingers with poor results. There were no complaints about nail deformity or skin abnormality. On multivariate analysis, significant predictors of poor postoperative motion were increased age chronic case, remained joint step-off, excess flexed fixation angle, and long-term wire placement. Extremely flexed fixation and chronic case easily causes extension loss in the DIP joint. In closed extension block pinning, joint fixation with an extreme flexion angle should be avoided and the pinning wire should be removed as soon as possible after confirming bony union.

Corrélation entre l’angle d’insertion de la broche bloquant l’extension et la perte d’extension dans les fractures digitales en maillet (mallet finger)

IntroductionExtension-block pinning represents a simple and reliable surgical technique. Although this procedure is commonly performed successfully, some patients develop postoperative extension loss. To date, the relationship between extension-block Kirschner wire (K-wire) insertion angle and postoperative extension loss in mallet finger fracture remains unclear. HypothesisWe aimed to clarify this relationship and further evaluate how various operative and non-operative factors affect postoperative extension loss after extension-block pinning for mallet finger fracture. Materials and methodA retrospective study was conducted to investigate a relationship between extension block K-wire insertion angle and postoperative extension loss. The inclusion criteria were: (1) a dorsal intra-articular fracture fragment involving 30% of the base of the distal phalanx with or without volar subluxation of the distal phalanx; and (2) <3 weeks delay from the injury without treatment. Extension-block K-wire insertion angle and fixation angle of the distal interphalangeal (DIP) joint were assessed using lateral radiograph at immediate postoperative time. Postoperative extension loss was assessed by using lateral radiograph at latest follow-up. Extension-block K-wire insertion angle was defined as the acute angle between extension block K-wire and longitudinal axis of middle phalangeal head. DIP joint fixation angle was defined as the acute angle between the distal phalanx and middle phalanx longitudinal axes. ResultsSeventy-five patients were included. The correlation analysis revealed that extension-block K-wire insertion angle had a negative correlation with postoperative extension loss, whereas fracture size and time to operation had a positive correlation (correlation coefficient for extension block K-wire angle: −0.66, facture size: +0.67, time to operation: +0.60). When stratifying patients in terms of negative and positive fixation angle of the DIP joint, the independent t-test showed that mean postoperative extension loss is −3.67° and +4.54° (DIP joint fixation angles of <0° and ≥0°, respectively, P=0.024). When stratifying patients in terms of extension-block K-wire insertion angle (30°, 30–40°, >40°), ANOVA showed significantly less postoperative extension loss for higher insertion angles (>40°) than for medium insertion angles (30–40°). Mean postoperative extension loss difference between higher insertion angle (>40°) and medium insertion angle (30–40°) was 11° (P=0.002). DiscussionUsing an insertion angle of the extension-block K-wire of 40–45° and a slightly hyperextended position of the DIP joint may help reducing postoperative extension loss. Level of evidenceTherapeutic level III.

Reduction Loss after Extension Block Kirschner Wire Fixation for Treatment of Bony Mallet Finger

Reduction Loss after Extension Block Kirschner Wire Fixation for Treatment of Bony Mallet Finger

Correlation between extension-block K-wire insertion angle and postoperative extension loss in mallet finger fracture

IntroductionExtension-block pinning represents a simple and reliable surgical technique. Although this procedure is commonly performed successfully, some patients develop postoperative extension loss. To date, the relationship between extension-block Kirschner wire (K-wire) insertion angle and postoperative extension loss in mallet finger fracture remains unclear. HypothesisWe aimed to clarify this relationship and further evaluate how various operative and non-operative factors affect postoperative extension loss after extension-block pinning for mallet finger fracture. Materials and methodA retrospective study was conducted to investigate a relationship between extension block K-wire insertion angle and postoperative extension loss. The inclusion criteria were: (1) a dorsal intra-articular fracture fragment involving 30% of the base of the distal phalanx with or without volar subluxation of the distal phalanx; and (2) <3 weeks delay from the injury without treatment. Extension-block K-wire insertion angle and fixation angle of the distal interphalangeal (DIP) joint were assessed using lateral radiograph at immediate postoperative time. Postoperative extension loss was assessed by using lateral radiograph at latest follow-up. Extension-block K-wire insertion angle was defined as the acute angle between extension block K-wire and longitudinal axis of middle phalangeal head. DIP joint fixation angle was defined as the acute angle between the distal phalanx and middle phalanx longitudinal axes. ResultsSeventy-five patients were included. The correlation analysis revealed that extension-block K-wire insertion angle had a negative correlation with postoperative extension loss, whereas fracture size and time to operation had a positive correlation (correlation coefficient for extension block K-wire angle: −0.66, facture size: +0.67, time to operation: +0.60). When stratifying patients in terms of negative and positive fixation angle of the DIP joint, the independent t-test showed that mean postoperative extension loss is −3.67° and +4.54° (DIP joint fixation angles of <0° and ≥0°, respectively, P=0.024). When stratifying patients in terms of extension-block K-wire insertion angle (30°, 30°–40°, >40°), ANOVA showed significantly less postoperative extension loss for higher insertion angles (>40°) than for medium insertion angles (30°–40°). Mean postoperative extension loss difference between higher insertion angle (>40°) and medium insertion angle (30°–40°) was 11° (P=0.002). DiscussionUsing an insertion angle of the extension-block K-wire of 40°–45° and a slightly hyperextended position of the DIP joint may help reducing postoperative extension loss. Level of evidenceTherapeutic level III.