A 33-year-old woman presented with acute nonspecific knee pain, 6months postpartum. MR imaging, computed tomography and radiography were performed and a proximal tibia plateau insufficiency fracture was detected. Bone densitometry demonstrated mild postpartum osteoporosis. To our knowledge these findings have not been described in this location and in this clinical setting. The etiology of the atraumatic fracture of the tibia is presumed to be due to a low bone mineral density. The bone loss was probably due to pregnancy, lactation and postpartum hormonal changes. There were no other inciting causes and the patient was normocalcemic. We discuss the presence of a postpartum stress fracture in a hitherto undescribed site in a patient who had lactated following an uncomplicated pregnancy and had no other identifiable cause for a stress fractur

Anderson, S.

Ballmer, F.

Clemetson, I.

Lippuner, K.

Popp, A.

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Skeletal Radiol (2004) 33:96–98DOI 10.1007/s00256-003-0721-2 C A S E R E PORTI. A. ClemetsonA. PoppK. LippunerF. BallmerS. E. AndersonPostpartum osteoporosis associatedwith proximal tibial stress fractureReceived: 18 July 2003Revised: 27 October 2003Accepted: 28 October 2003Published online: 9 January 2004 ISS 2004I. A. Clemetson ()) · S. E. AndersonDepartment of Radiology,University Hospital of Bern, Inselspital,3010 Bern, Switzerlande-mail: isabelle.clemetson@insel.chTel.: +41-31-6322527Fax: +41-31-6324874A. Popp · K. LippunerDepartment of Osteology,University Hospital of Bern, Inselspital,3010 Bern, SwitzerlandF. BallmerKnee and Sports Medicine Unit,Lindenhofspital Bern,3012 Bern, SwitzerlandAbstract A 33-year-old woman pre-sented with acute nonspecific kneepain, 6 months postpartum. MR im-aging, computed tomography andradiography were performed and aproximal tibia plateau insufficiencyfracture was detected. Bone densi-tometry demonstrated mild postpar-tum osteoporosis. To our knowledgethese findings have not been de-scribed in this location and in thisclinical setting. The etiology of theatraumatic fracture of the tibia ispresumed to be due to a low bonemineral density. The bone loss wasprobably due to pregnancy, lactationand postpartum hormonal changes.There were no other inciting causesand the patient was normocalcemic.We discuss the presence of a post-partum stress fracture in a hithertoundescribed site in a patient who hadlactated following an uncomplicatedpregnancy and had no other identifi-able cause for a stress fracture.Keywords Tibial insufficiencyfracture · Postpartum osteoporosis ·Dual-energy X-ray absorptiometry ·MR imaging of the knee ·RadiographyIntroductionInsufficiency fractures associated with postpartum osteo-porosis are well known though uncommon. Previous sitesof insufficiency fractures related to pregnancy andpostpartum state described in the literature includesacrum [1, 2, 3]; superior and inferior pubic bones,ischiopubic arch and pubic body [4]; proximal femoraldiaphysis, neck of femur and subcapital hip region [5, 6];rib [7, 8] and vertebrae [8]. Sports stress fractures are welldocumented in the tibia, pelvis, fibula, humerus and 2nd,3rd and 4th metatarsal bones [9]. Risk factors ofpostpartum fracture are thought to be rapid and excessiveweight gain during pregnancy [1, 4], transient osteopenia/osteoporosis during pregnancy [2, 6, 8, 10], increase inphysical activity such as jogging and aerobics during andimmediately after pregnancy [1, 11], cesarian section orassisted vaginal delivery [11, 12], muscular forces actingon ribs during the enlargement of the uterus [7] andendocrine and hormonal influences [13, 14, 15]. None ofthese causes were present in our patient, who developed atibial stress fracture 6 months postpartum, at the end ofher lactation period.Case reportThe patient gave full written informed consent for publication ofher history and imaging details.A 33-year-old woman presented with nonspecific acute kneepain, 6 months postpartum. Her pregnancy was uncomplicated. Shehad no massive weight gain and did not exercise excessively duringor after the pregnancy. In particular there was no history of trauma,excessive walking or cycling. Apart from a small daily walk withthe new baby, accompanied by her two other children, she hadnormal daily activities. She was at the end of her nursing period (atotal of 5 months) and there was no history of fracture or a familyhistory of bone disease. There was no use of steroid medication or97excessive alcohol intake reported. As the patient had no history oftrauma or of overuse, dual-energy X-ray absorptiometry (DXA)was performed (Hologic QDR 4500c, Hologic, Bedford, Mass.).Low bone mineral density (BMD) was found at the lumbar spine(L3: 0.954 g/cm2, T-score 1.2 SD, Z-score 1.2 SD), thecontralateral femoral neck (0.727 g/cm2, T-score 1.1 SD, Z-score0.9SD) and distal tibial epiphysis (0.623 g/cm2, T-score 1.5 SD,Z-score 1.3 SD). Metabolic investigation showed diminishedurinary calcium, normal blood calcium levels (ionized and total), ablood phosphate concentration at the upper limit of normal, andnormal levels of 25-hydroxyvitamin D, parathyroid hormone (intactPTH), osteocalcin and a normal urinary deoxypyridinoline/creati-nine ratio. There were no signs of infection or malignancy.Underlying pathologies such as osteomalacia were excluded.Initial radiographs of the knee were normal. Because ofpersisting knee pain MR imaging was performed and showed aninsufficiency fracture of the right proximal tibial plateau associatedwith a large area of altered marrow signal. There was no evidenceof fracture displacement (Fig. 1). A second radiograph of the kneewas performed 3 months later, which showed a region of sclerosishighly suggestive of a fracture of the proximal tibial plateau(Fig. 2). CT was performed to exclude the rare possibility of osteoidosteoma associated with a stress fracture, as requested by theconsulted orthopaedic surgeon (Fig. 3). The patient was then treatedFig. 1 A Coronal T1-weighted MR image (TR: 560, TE: 15) showsa medial tibial plateau insufficiency fracture (arrow). B CoronalSTIR image (Short Tau Inversion Recovery) (Ti: 180, TR: 4200,TE: 96) shows markedly altered bone marrow signal in theproximal medial tibia (white arrow) and an insufficiency fractureline (thin black arrow). C Sagittal T2-weighted image (TR: 4000,TE: 96) shows the insufficiency fracture (arrow)Fig. 2 Frontal radiograph of the right knee 3 months after the onsetof acute atraumatic knee pain with an area of sclerosis in theproximal medial tibial plateau (arrow) Fig. 3 Computed tomographic sagittal reformatted image showsagain the insufficiency fracture (arrow)98References1. Hoang TA, Nguyen TH, Daffner RH,Lupetin AR, Deeb ZL. Case report 491.Stress fracture of the right sacrum.Skeletal Radiol 1988; 17:364–367.2. Schmid L, Pfirrmann C, Hess T,Schlumpf U. Bilateral fracture of thesacrum associated with pregnancy: acase report. Osteoporos Int 1999;10:91–93.3. Thienpont E, Simon JP, Fabry G. Sacralstress fracture during pregnancy: a casereport. Acta Orthop Scand 1999;70:525–526.4. Mikawa Y, Watanabe R, Yamano Y,Miyake S. Stress fracture of the body ofthe pubis in a pregnant woman. Casereport. Arch Orthop Trauma Surg 1988;107:193–194.5. Billey T, Dromer C, Pages M, CaulierM, Lassoued S, Fournie B. Spontaneousfracture of the femoral neck in hipalgodystrophy in pregnancy. A proposof a case and review of the literature.Rev Rhum Mal Osteoartic 1992;59:494–496.6. Knaepler H, Tamm J. Spontaneousfractures of the neck of the femuroccurring in pregnancy in the absenceof pregnancy osteoporosis. Un-fallchirurgie 1984; 10:96–99.7. Baitner AC, Bernstein AD, Jazrawi AJ,Della Valle CJ, Jazrawi LM. Sponta-neous rib fracture during pregnancy. Acase report and review of the literature.Bull Hosp Joint Dis 2000; 59:163–165.8. Gruber HE, Gutteridge DH, Baylink DJ.Osteoporosis associated with pregnancyand lactation: bone biopsy and skeletalfeatures in three patients. Metab BoneDis Rel Res 1984; 5:159–165.9. Pavlov H, Nelson TL, Warren RF, TorgJS, Burstein AH. Stress fractures of thepubic ramus. A report of twelve cases. JBone Joint Surg Am 1982; 64:1020–1025.10. Wattanawong T, Wajanavisit W, Lao-hacharoensombat W. Transient osteo-porosis with bilateral fracture of theneck of the femur during pregnancy: acase report. J Med Assoc Thai 2001; 84[Suppl 2]:516–519.11. Moran JJ. Stress fractures in pregnancy.Am J Obstet Gynecol 1988; 158:1274–1277.12. Bushsbaum HJ. Healing of experimen-tal fractures during pregnancy. ObstetGynecol 1970; 35:613–615.13. Levav AL, Chan L, Wapner RJ. Long-term magnesium sulfate tocolysis andmaternal osteoporosis in a triplet preg-nancy: a case report. Am J Perinatol1998; 15:43–46.14. Lippuner K, Zehnder HJ, Casez JP,Takkinen R, Jaeger P. PTH-relatedprotein is released into the mother’sbloodstream during lactation: evidencefor beneficial effects on maternal cal-cium-phosphate metabolism. J BoneMiner Res 1996; 11:1394–1399.15. Reid IR, Wattie DJ, Evans MC, BudayrAA. Post-pregnancy osteoporosis asso-ciated with hypercalcaemia. Clin En-docrinol (Oxf) 1992; 37:298–303.16. McFarland EG, Giangarra C. Sacralstress fractures in athletes. Clin Orthop1996; 329:240–243.with calcium 500 mg daily for 6 months and 10 weeks on crutcheswith non-weight-bearing. The patient is currently doing well.DiscussionInsufficiency fractures are common in joggers [16],military recruits, the elderly, postmenopausal women,and patients with osteopenia due to use of steroids,metabolic or endocrine causes [14, 15].Bushsbaum [12] noted as a possible cause of stressfractures in the pelvic region that during pregnancy theendocrinological balance is changed, causing an alterationof the connective tissue that results in ligament laxity anddelayed clinical healing. Moran [11] states that ligamentlaxity due to hormonal changes in pregnancy and,therefore, muscular stress action in untrained patients,can result in stress/fatigue fractures particularly duringdelivery. Pavlov et al. [9] showed in their study thatjoggers with stress fractures all had ligament laxity.Jogging or other sports activity or ligamentous laxity doesnot appear to be the etiology in our case. Other possiblemechanisms of postpartum osteoporosis include second-ary bone loss due to prolonged bed rest or the use ofmagnesium sulfate tocolysis [13], or merely factorsrelated to pregnancy and to lactation [8]. However, theexact cause remains somewhat speculative. It is assumedthat metabolic and endocrine changes in pregnancy areresponsible for the development of stress fracture [13].The metabolic changes of pregnancy and lactation relateto the production of PTH-like peptide during this period[14]. With lactation and with the production of PTH-likepeptide there is increased bone resorption and, withdecreased nutritional calcium intake, there was a negativecalcium balance in our patient reflected in her low urinarycalcium. This led to a stress fracture.Our case is interesting because our patient’s only riskfactor was her postpartum lactating state. While second-ary causes of bone loss could be ruled out, pregnancy andlactation associated with low calcium intake werepresumed to be the underlying mechanism. Low urinarycalcium excretion and a blood phosphate level at theupper limit of normal are a typical constellation duringlactation. On the assumption that bone loss duringpregnancy and lactation is self-limiting, BMD shouldincrease after nursing is stopped, which could explainwhy the BMD values of our patient were only slightlydiminished at the time of measurement. The MR appear-ance showed an altered bone marrow signal in theproximal medial tibia and a fracture line. In the absenceof a history of trauma, postpartum insufficiency fractureof the proximal tibia was diagnosed.The patient’s tibial stress fracture was treated as apostpartum insufficiency stress fracture with oral calciummedication for 6 months and conservative non-weight-bearing for 10 weeks.

Postpartum osteoporosis associated with proximal tibial stress fracture

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Postpartum osteoporosis associated with proximal tibial stress fracture

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