Classic Tibial Stress Fracture
Transcription
Classic Tibial Stress Fracture
Karl B. Fields, MD Moses H Cone Sports Medicine Fellowship A stress fracture is an overuse injury resulting in structural damage to bone from repetitive weight bearing or increasing stressful muscular activity too quickly Stress fractures should be differentiated from insufficiency fractures which are bone injury in weakened bone from normal activity Olympic victors are those who did not squander their powers by early and over training. Aristotle 200 BC Identified by Breithaupt in Prussian soldiers in 1855 1897 first x-rays of metatarsal stress fractures 1958 Devas associates these injuries with athletes Prospective trial of collegiate athletes showed 6.9% F and 2%M over 2 years Rates in intense training reported much higher in 20% to 30% range for 1 year Military recruits range from 1 to 5% in basic training of 8 to 14 weeks with much higher rates in special forces and groups who train > 15 hours per week White males and females have 2.3 relative risk of stress fracture versus blacks relative risk in women ranges from 1.3 to 3.5 times as high as men Previous Stress fracture > 5x higher rate Low BMD (each SD decrease, 2x higher rate) – based on prospective trial AJSM Now most common site in men primary sports are distance running, basketball, soccer and ballet Sxs of MTSS that localize Differential Dx includes MTSS, compartment syndrome, muscular strains Localized tenderness that usually starts along posterior medial border of tibia Most commonly at junction of distal and medial third of tibia but can be anywhere localized swelling + hop test + tuning fork Video of Fracture Site Distal third of tibia and medial third along medial and posterior border heal well Anterior tibia - middle third classic problems with “dreaded black line” Complicated healing high tibia/ anterior tibia, tibial plateau Adolescents more typically have injury to the proximal metaphysis RICE long air splints and padded lower extremity appliances – Cochrane rates these as speeding healing by ~ 42 days No medications have proven benefit although calcium and Vit D did lessen risk preventively in studies of naval recruits Substituted training schedules and cross training Proximal 1/3 : 43% one to two mos; 57% > 2mos. Middle 1/3 : 48% one to two mos.; 52% > 2 mos. Distal 1/3 : 53% one to two mos. ; 47% > 2 mos. “Dreaded anterior black line” Higher grade stress fractures that extend across more than 50% of diameter Tibial plateau Medial Malleolus Individuals with significant anatomical or biomechanical problems Medial Malleolus 21 year old hurdler History of metatarsal stress fracture last season Insidious onset of pain left tibia since this fall, now with pain with every step, night pain Thought this was “shin splints” Nl periods, wt, eating habits Probably most common stress fracture in women 2nd, 3rd and 4th metatarsals all common First and fifth metatarsals are uncommon stress fractures and often difficult to heal Standard Xrays are of limited value MSK US may emerge as preferred dx test Avulsion fractures are not typically stress fractures Jones fractures generally heal faster with pinning Stress fracture is in the diaphysis and not in the articulation These can be treated conservatively Trend has been to pin these as well Scaphoid Navicular Femoral Neck Pars intra-articularis Talar Dome Usually present with groin pain Commonly missed for several months and considered groin strains Differential diagnosis includes AVN, SCFE, DJD, Idiopathic Osteoporosis of the Hip Back pain in adolescents is usually organic in nature These commonly occur in several sports in which back extension is repetitive One leg hyperextension test – “flamingo” Bilateral stress fractures can slip and lead to spondylolithesis Often are “ankle sprains” that will not heal or result in persistent pain OCD lesions can occur and may require arthroscopy to remove Healing may not take place without putting ankle to rest for 6 weeks and sometimes NWB Talar Dome Fracture Lateral Corner 14-35% of all stress fractures 59% of Navicular fractures are in track athletes No significant risk factors Diagnosis averages 4 months Delay is bad as this can cause non-union Limitation of activity has only a 26% cure rate Calcaneus Talu s Navicu lar Cuneifor ms During foot strike, the Navicular becomes impinged, mostly in the central 1/3, a relatively avascular area. Aching pain in the dorsal midfoot Radiates along the medial arch Pain increases with activity such as running, jumping, hopping Good ROM, strength. No ecchymosed, or swelling “N spot” tender 81% Plain radiographs: 33% sensitive Even then require 10d to 3w to show up Triple phase bone scan: 100% sensitive Remains positive for 2 years However, positive bone scans must always be followed up with CT or MRI due to lack of resolution Non-weight bearing cast for >=6 weeks: 86% Limitation of activity >=6 weeks: 26% Nothin’: 20% Operation: failure of above, if non-union or in young if need for quick healing (3.8 mo vs. 5.6 mo) Always check for tenderness over the “N spot;” any tenderness requires 2 more weeks of non-weight bearing. Scintigraphy is highly sensitive but not specific MRI detects the full range of stress injury Most common MRI findings: 1.Bone marrow edema(97.2%)…first evidence of stress injuries to bone 2.Periosteal edema(88.9%)…with or after periosteal edema on MRI, cortical rxn seen on conventional radiograph 3. Actual fracture line(38.9%)…also strongly suggested by endosteal edema Cost is a major drawback to MRI Standard Xrays miss 30% to 50% of stress fractures even when repeated Bone Scans and CT are also very expensive CT radiation exposure is a major risk Radio-isotope issues are affecting scanning MSK US may gain an increasing role although radiology in USA will be very reluctant to endorse this