ONLINE EXCLUSIVE Samuel Dettling, BSE; ORIGINAL RESEARCH Dennis S. Weiner, MD Akron Children’s Hospital, Ohio (Mr. Dettling and Dr. Weiner); Management of bow legs in Case Western Reserve School of Medicine, Cleveland, Ohio children: A primary care protocol (Mr. Dettling) [email protected] This protocol, which is designed to coincide with well- The authors reported no potential conflict of interest child visits, distinguishes between normal physiologic relevant to this article. maturation and cases requiring referral. ABSTRACT manage most children presenting with bow Objective u To reduce unnecessary orthope- legs. Management focuses on following the dic referrals by developing a protocol for man- progression or resolution of varus with regular aging physiologic bow legs in the primary care follow-up. For patients presenting with bow environment through the use of a noninvasive legs, we recommend a follow-up protocol technique that simultaneously tracks normal using mainly well-child checkups and a simple varus progression and screens for potential clinical assessment to monitor varus progres- pathologic bowing requiring an orthopedic sion and screen for pathologic bowing. referral. Methods u Retrospective study of 155 pa- ow legs in young children can be a tients with physiologic genu varum and concern for parents.1,2 By far, the most 10 with infantile Blount’s disease. We used common reason for bow legs is physi- B 3-5 fingerbreadth measurements to docu- ologic genu varum, a nonprogressive stage ment progression or resolution of bow of normal development in young children legs. Final diagnoses were made by one that generally resolves spontaneously with- orthopedic surgeon using clinical and radio- out treatment.1,6-11 Normally developing chil- graphic evidence. We divided genu varum dren undergo a varus phase between birth patients into 3 groups: patients presenting and 18 to 24 months of age (MOA), at which with bow legs before 18 months of age time there is usually a transition in align- (MOA), patients presenting between 18 and ment from varus to straight to valgus (knock 23 MOA, and patients presenting at knees), which will correct to straight or mild 24 MOA or older for analyses relevant to the valgus throughout adolescence.1,6,7,9,10,12-17 development of the follow-up protocol. The most common form of pathologic Results u Physiologic genu varum patients bow legs is Blount’s disease, also known as walked earlier than average infants (10 months tibia vara, which must be differentiated from vs 12-15 months; P<.001). Physiologic genu physiologic genu varum.8-10,15,18-24 The progres- varum patients presenting before 18 MOA sive varus deformity of Blount’s disease usu- demonstrated initial signs of correction ally requires orthopedic intervention.1,10,23-26 between 18 and 24 MOA and resolution by Early diagnosis may spare patients complex 30 MOA. Physiologic genu varum patients pre- interventions, improve prognosis, and limit senting between 18 and 23 MOA demonstrated complications that include gait abnormali- initial signs of correction between 24 MOA and ties,4,8,10,27 knee joint instability,4,24,27 osteoar- 30 MOA and resolution by 36 MOA. thritis,9,20,27 meniscal tears,27 and degenerative Conclusion u Primary care physicians can joint disease.19,20,27 CONTINUED JFPONLINE.COM VOL 66, NO 5 | MAY 2017 | THE JOURNAL OF FAMILY PRACTICE E1 Although variables such as walking age, correction to less than or equal to half of the race, weight, and gender have been suggested varus angulation at presentation. For inclu- as risk factors for Blount’s disease, they have sion in the age-at-resolution analysis, a child not been useful in differentiating between must have been evaluated at regular follow-up Blount’s pathology and physiologic genu visits (all rechecks within 8 months). varum.1,4,5,7,10,20,28 In the primary care setting, To measure varus distance, we used the distinguishing physiologic from pathologic fingerbreadth method described by Weiner forms of bow legs is possible with a thorough in a study of 600 cases (FIGURE).6 This simple history and physical exam and with radio- technique, which requires no special equip- graphs, as warranted.1,2,15 More than 40% of ment, accurately detected differences in genu varum/genu valgum cases referred varus angulation and tracked the normal pat- for orthopedic consultation turn out to be tern of lower limb angular development. The the physiologic form,2 suggesting a need for patient should be supine on the examination guidelines in the primary care setting to help table with legs extended. With one hand, the direct referral and follow-up. The purpose of examiner holds the child’s ankles together, this study was to provide recommendations ensuring the medial malleoli are in contact. to family physicians for evaluating and man- With the other hand, the examiner mea- aging children with bow legs. sures the fingerbreadth distance between the medial femoral condyles. Alternatively, a More than 40% ruler may be used to measure the distance. of genu varum Materials and methods This latter method may be especially useful cases referred This study, approved by the Internal Review in practices where the patient is likely to see for orthopedic Board of Akron Children’s Hospital, is a ret- more than one provider for well child care. consultation rospective review of children seen by a single We divided the genu varum subject turn out to be pediatric orthopedic surgeon (DSW) from group into 3 subgroups by age at presen- the physiologic 1970 to 2012. Four-hundred twenty-four tation: 103 subjects were younger than form. children were received for evaluation of bow 18 months; 47 were 18 to 23 months; and legs. Excluded from our final analysis were 5 were 24 months or older. We used the data 220 subjects seen only once for this specific analysis toolkit in Microsoft Excel 2013 to referral and 39 subjects diagnosed with a perform a statistical analysis of study vari- condition other than genu varum or Blount’s ables. We assumed the genu varum popula- disease (ie, rickets, skeletal dysplasia, tion is a normally distributed population. We sequelae of trauma, or infection). Ten sub- used a 95% confidence level α( =0.05) for all jects with Blount’s disease and 155 subjects calculations of confidence intervals (CIs), with physiologic genu varum were included student t-tests, and tolerance intervals. Based in the final data analysis. on the data analysis results, we developed a In addition to noting the age at which a series of follow-up and referral guidelines for patient walked independently, at each visit practitioners. we documented age and the fingerbreadth (varus) distance between the medial femoral condyles with the child’s ankles held together. Results Parents reported age of independent walking The mean walking age for those diagnosed for just 3 children with Blount’s disease and with physiologic genu varum was 10 months for 134 children with physiologic genu varum. (95% CI, 9.8-10.4), which is significantly Study variables for the genu varum data analy- younger than the 12 months of age (at the ear- sis were age of walking, age at presentation, liest) typical of toddlers in general (P<.001). age at varus correction, age at varus resolution, There was no significant difference between time between presentation and varus cor- the walking age of male and female children rection, and time between presentation and diagnosed with genu varum (P=.37). varus resolution. Varus correction is defined Of the children presenting with the pri- as any decrease in varus angulation since pre- mary complaint of bow legs, 6% subsequently sentation. Varus resolution is defined as varus developed Blount’s disease. These patients pre- E2 THE JOURNAL OF FAMILY PRACTICE | MAY 2017 | VOL 66, NO 5 BOW LEGS IN CHILDREN sented at a mean age of 20.9 months and were FIGURE diagnosed at a mean age of 23.9 months. Fol- Measuring genu varum by fingerbreadths lowing the Blount’s disease diagnosis, we initi- ated therapy in all cases (3 surgical, 7 bracing). Physiologic genu varum patients pre- sented at a mean age of 16.4 months, with only 3.23% presenting at older than 23 months. On average, physiologic genu varum patients presenting before 24 months of age showed measurable varus correction 5 months after presentation and achieved varus resolu- tion 7.3 months after presentation (TABLE 1). Assuming the patient population is normally distributed, we can be 95% confident that 95% of physiologic genu varum patients pre- senting before 18 months of age will show measurable varus correction by 24 months and will resolve without intervention by 30 months (TABLE 2). Patients presenting between 18 and 23 months of age should show measurable varus correction by 30 months and resolution by 36 months (TABLE 3). Discussion Primary care physicians have the abil- ity to differentiate physiologic genu varum from pathologic forms of bow legs with a thorough history, physical exam, and 1,2,13 radiographic examination, if necessary 1,7,8,10,12,14,18-20,22,24,27 (TABLE 4 ). Several approaches IMAGE: © MICHELE GRAHAM to differentiating Blount’s disease and physi- ologic genu varum have been described in the literature.1,4,7,8,10,14,22,23 The average age at which children begin to walk independently is between 13 and 15 months.5,18,29-31 Recently, it has been suggested that the range be expanded to With the patient supine and legs extended, hold the child’s ankles together 30 with one hand, ensuring the medial malleoli are in contact. With the other include 12 months of age. The asso- hand, measure the fingerbreadth distance between the medial femoral ciation between early walking (at 10- condyles.