74 2024 BrachyMetatarsia and Polydactyly PDF

ETYMOLOGY Poly- Greek(pollus/polloi)- “Much/Many” -Dactyl- Middle English, from Greek daktulos”Finger” Brachy- Greek- Brachus- ”Short” Metatarsia- Latin- “Of the metatarsals” “Charybdis and Scilla”-Allesandro Allori Italian Fresco segment (c. 1535-1607 ETYMOLOGY II Macrodactyly- Greek makros “Long/L...

ETYMOLOGY Poly- Greek(pollus/polloi)- “Much/Many” -Dactyl- Middle English, from Greek daktulos”Finger” Brachy- Greek- Brachus- ”Short” Metatarsia- Latin- “Of the metatarsals” “Charybdis and Scilla”-Allesandro Allori Italian Fresco segment (c. 1535-1607 ETYMOLOGY II Macrodactyly- Greek makros “Long/Large” + dactyl “Finger” Ectrodactyly- Greek ectroma “Abortion” + dactyl “Finger” Delta Phalanx- Delta, Phonecian daleth “Door” + Phalanx Greek- “spear formation” Longitudinal Epiphyseal Bracket- term coined by Light and Ogden in 1981 to describe this metatarsal malformation otherwise known as “delta phalanx of the metatarsal” “Alexander and Darius III at Gaugamela, Mosiac Philoxenenus of Eretria circa 315 BC POLYDACTYLY Duplication of one of more digits Incidence is roughly 1.7 per 1000 live births Supernumerary digits Bilateral appearance in about half of observed cases Can arise from/ affect any digit Ernest Hemmingway and one of his six-toed cats CLINICAL APPEARANCE Duplication of one or more digits Around 30% have a family member with polydactyly as well May or may not present with syndactyly of affected digits ­ Over 97 genetic conditions recognized in association with polydactyly including trisomy 13, Fanconi anemia and Greigs syndrome. Chief compliant is usually pain, difficulty fitting shoes or walking. ­ Those involving the great toe present with frequent Hallux Varus RADIOGRAPHIC APPEARANCE Diagnosis can be clinical (in cases of obvious extra digits) Radiographic appearance is most helpful for surgical preplanning Duplication can involve entire ray, or segments thereof POLYDACTYLY VARIANTS Any metatarsal can display these types of radiographic/clinical malformations POLYDACTYLY SUBTYPES Preaxial- Medial border of the foot (first toe or ray duplication) Central (duplication of the second-fourth toes or rays) Postaxial (fifth toe or ray duplication) ­ Most common by a wide margin (80%+ of cases) “AXIAL” Embryonic developmental term denoting the separation of cranial (preaxial) from caudal (postaxial) As the limb develops a pre and postaxial vein will be formed ­ In the leg the preaxial vein is the greater saphenous ­ Postaxial vein is the lesser saphenous “AXIAL II” Continuing embryonic development gives rise to the pre and postaxial muscle mass The original pre and postaxial muscle masses divide into anterior and posterior segments Finally, the paired anterior and posterior segments fuse into the primordial forms of the flexor and extensor muscles of the adult POLYDACTYLY TREATMENT Conservative: only for asymptomatic cases ­ Often presents with painful hallux varus Surgical: removal of the most peripheral supernumerary digit ­ May have to get creative as to which one this is Delay surgery until 1 year of age at least ­ Reduce complications from anesthesia POLYDACTYLY SURGICAL PREPLANNING Plan your incisional approach to: ­ Remove the extra bone adequately ­ Remove excess soft tissue ­ Preserve the N/V anatomy Preserve tendinous attachments ­ Avoid scar contractures LET'S DO: A PREAXIAL POLYDACTYLY EXCISION Note the large size of the great toe and medial deviation Plan incision to spare N/v anatomy and reduce risk of contractures Incision in this case needs to extend to the MTPJ for capsular re-approximation ­ Must carefully re-balance the capsule to prevent postoperative hallux varus LET'S DO: A PREAXIAL POLYDACTYLY EXCISION Remove/resect the extra bone This may need to come out in fragments as shown LET'S DO: A PREAXIAL POLYDACTYLY EXCISION For persistent or recurrent varus deformity a reverse akin type osteotomy may be performed For all preaxial polydactyly cases: carefully rebalance the MTPJ capsule to prevent recurrent hallux varus LET'S DO: A PREAXIAL POLYDACTYLY EXCISION A 0.62 K-wire may be utilized to retain the acceptable position of the toe POSTOPERATIVE CARE Same as toe amputation WBAT in surgical shoe and bulky dressing Sutures out at 2 weeks Monitor closely for signs of digital or flap necrosis (top) and ischemia (bottom) BRACHYMETATARSIA Reduced length of the metatarsal Incidence 3-5 per 1000 people Women are 25 times more likely than men to be affected Most commonly affects the fourth ray ­ Bilaterally in more than 70% BRACHYMETATARSIA EVALUATION Chief complaint: ­ cosmetic disfigurement ­ pain with shoes ­ pressure on the short toe Radiographs: ­ Deformity may be obvious ­ Can also use the metatarsal parabola and parabola formed by tips of toes. RADIOGRAPHIC EVALUATION Weight bearing AP foot is the most useful view for preoperative evaluation Use preoperative radiographic measurements to plan surgical lengthening ­ How long do you want to make the metatarsal? BRACHYMETATARSIA TREATMENT Conservative: shoe gear modification, observation Surgical ­ Single-stage lengthening ­ Callus-distraction Surgical goals ­ Alleviate pain ­ Restore metatarsal parabola ­ Establish cosmetically acceptable appearance SINGLE-STAGE LENGTHENING V-to-Y skin plasty vs longitudinal incision Lengthen EDL, section EDB ­ FDL tenotomy rarely indicated Transverse osteotomy is made in the short metatarsal Bone graft block of pre-measured desired length inserted Secured with K-wire and overlying dorsal plate SINGLE STAGE LENGTHENING LIMITATIONS Size of the bone graft (smallest of these two) ­ Not more than 15mm ­ or ­ Not more than 25% of the existing metatarsal ­ Consider Donor-site morbidity Malalignment ­ Angulation of distal fragment Nonunion ­ Two fusion surfaces=two potential nonunion sites. Advantages: faster time to healing, metaphyseal location POSTOPERATIVE CARE: SINGLE STAGE LEGNETHING Fixate with wire or spanning plate Monitor toe for vascular interruption (ischemia) Partial weight bearing in heel-wedge shoe? Non weight bearing cast? CALLUS-DISTRACTION Mini-rail external fixator is applied to the metatarsal Bone is cut ­ Cortectomy? ­ Osteotomy? Metatarsal is gradually lengthened ­ Latency period of 5-14 days followed by lengthening ­ Optimal length 1mm per day ­ In 0.25mm increments every 6 hours CALLUS-DISTRACTION ADVANTAGES Superior quality of regenerated bone Ability to weight-bear immediately Larger deformities can be addressed ­ Lengthen up to 40% of metatarsal Disadvantages ­ Higher rate of complication ­ Pin tract infection ­ Angulation of distal fragment (single rail can only lengthen in one plane) ­ Angular deformity correction can be simultaneously address with semicircular ring fixator (bottom) ­ Longer time to healing ­ 16-20 weeks (leave fixator on until union) ­ Higher cost Surgical planning ­ Most fixators are monorail devices (single plane) ­ Insertion angle is ideally as shown ­ When inserting the first pin (percutaneously) hold the fixator in the desired position ­ Avoid angulations! LET'S DO: A CALLUSDISTRACTION Align pin using the AP view fluoroscopically The first pin is the distal-most pin Check lateral view to ensure BICORTICAL placement of the pin CALLUS DISTRACTION: THE FIRST PIN Fixator must be placed in a manner which ­ Fits on the metatarsal (all four pins ideally) ­ Allows an initial period of compression ­ Allows approach for cortectomy or osteotomy ­ Confirm radiographic alignment CALLUS DISTRACTION Small incision over planned site Dissect down to the bone (minimalize dissection of the periosteum) Cortecotomy: only cut the bone cortex (leave medullary bone) CALLUS DISTRACTION Osteotomy: through and through bone cut Confirm satisfactory placement of bone-cut Initially compress the osteotomy site 5-14 days CALLUS DISTRACTION Lengthen by 0.25mm every 6 hours for a total of 1mm daily Predetermine how much length you need ­ Impress upon the patient to ONLY do this much CALLUS DISTRACTION Overlengthening complications: ­ ­ ­ ­ CALLUS DISTRACTION: OVERLENGTHENING! Angulation MTPJ stiffness (jamming) Toe deviation Neurovascular compromise Many immediately weight bear DAILY pin care Frequent follow-up (at least weekly for the first several weeks) POSTOPERATIVE CARE Strict instructions on the fixator use (one quarter-turn 4 times daily) are mandatory (avoid over-lengthening)