Successful Outcomes Using a New Free Motion KAFO for Treatment of Infantile Blounts Disease
Joseph W. Whiteside, CO/LO
Non-surgical treatment of Blounts disease has been somewhat controversial. Studies have shown success with use of a drop lock or solid upright KAFO variations which are accepted as the gold standard for orthotic treatment1-4. A more recent study has shown a high rate of spontaneous correction when varying stages of severity, specific to Blounts Disease is present5. Compliance has been a primary limitation in the locked knee designs due to the altered gait pattern and overall perception of being impractical. Other risk factors related to failure include obesity, varus thrust and orthotic application at an age older than three1. To maximize results when managing bowing deformities of the lower limb, it is paramount to establish proper diagnosis, age appropriateness and progression of deformity. Differential diagnosis is multifactor based and primary in determining likelihood of deformity progression and orthotic outcome. The factors influencing progression include genetics1,6-9 obesity10 ethnicity, varus thrust, radiographic measures of severity, stage of deformity11-13 and unilateral vs. bilateral involvement1-3, 14,15.
Knee Ankle Foot Orthosis (KAFO) designs specific to Blounts disease and other bowing deformities of the knee have consisted of: solid single or double upright, single or double upright with drop lock hinge and single upright with posterior swivel hinge and Positive Track Telescoping ankle joint. The length of time an orthosis is worn in a 24 hour period is determined by the prescribing physician. Individual preference ranges from 23 hour wear versus daytime or nighttime wear. Recent data has shown an equal success rate in part time bracing in patients who wore their braces only at night time compared to those only braced during the day, both approximately 90%16.
Two cases are presented. Patient A is a child diagnosed with Blounts at age 2 who was originally fit with a traditional Double Solid Up-right KAFO (DSUK) design then transitioned to a new design at age 3 + 10. This new design, the V-Vas (Varum Valgum Adjustable Stress joint system Blounts KAFO (VVASBK) was chosen due to poor compliance and associated deformity progression after being treated with the DSUK for 17 months. The second patient B, was fitted with the custom VVASBK for orthotic management from the initiation of treatment. Initially the orthotist recommended traditional SSUK design because of previous success and familiarity with it. However, the pediatric orthopedic surgeon intervened preferring not to use the DSUK design due to a concern for patient noncompliance. The orthotist and pediatric orthopedist decided to proceed with the new hinged double upright free motion knee VVASBK. The benefits of the VVASBK compared to other traditional designs were the ability for full knee ROM in the joint design.
The specific design features of the VVASBK (figure a 1-5) include 1/8" polypropylene posterior opening thigh and tibial cuffs to simplify the donning and doffing process. A closed cell foam lining encompasses the inside of the thigh and tibial cuffs; it is designed to be removed to accommodate circumferential growth. To further accommodate growth, an adjustment to the length of the medial and laterally femoral and tibial uprights in 1/4" increments can be used to minimize remaking the orthosis for growth accommodation (figure a -4).
Tamarack® ankle joints, both medial and laterally allow relative dorsiflexion and plantarflexion while providing adequate M-L stability of the ankle. The medial and lateral ankle joint assures that the corrective forces are maximized proximally (it has been observed in the clinical setting that the use of only one medial or lateral ankle joint reduces the effectiveness of the proximal corrective forces). The ability to provide the corrective forces leading to the resolution of the skeletal malalignment is achieved through the unique design of the V-Vas Joint system. Success is attained through the joint's ability to isolate measured tibial (figure a -1), femoral (figure a -2) and or tibio-femoral alignment (figure a -3)in 2° and 4° increments respectively, either independent or dependent of each other (figure a -5) as viewed in the coronal plane. It is believed that the resulting effect of the V-Vas Joint Systems dynamic adjustability capabilities actually provides a distracting force. This distracting force is what maintains the four point correction not only in full extension as do all the previous designs, but through out the full range of knee motion that is unique to the V-Vas Joint System. The unique mechanisms inherent to the overall design is what is at the heart of the VVASBK's ability to exert the controlled corrective forces necessary to achieve the following positive outcomes and provide a more natural environment for the developing child.
Patient A is an obese Hispanic male. The initial radiographs confirmed the diagnosis of Blounts disease and physical exam identified a gait exaggerated varus thrust. He was referred to the local orthotist for measurement and eventual fitting. Orthotic treatment was initiated at the age of 2 + 1 years. At the age of 2 + 5, a follow up radiograph (figure a -1) was obtained and the DSUK was discontinued due to compliance issues. The family was instructed about the possible potential of spontaneous correction or worsening which would lead to surgical treatment. At the ten month follow up, radiographs (figure a -2) revealed progression of the deformity and traditional DSUK's were re-fitted to offset recurring progression of the deformity. Six months later radiographs confirmed an improvement of the deformity (figure a -3). At the age of 3 + 4 years or nine months after the previous visit, new radiographs were obtained (figure a -4) revealing recurrence of the deformity due to non compliance with DSUK brace wear. During the same visit, the doctor consulted with the orthotist and a decision was made to proceed with the VVASBK. Cast impressions and associated measurements were taken for the VVASBK, sent for custom fabrication and the patient was fitted with his new VVASBK in a timely manor. Anatomical Concepts Inc. USA is the fabricator and distributor for the V-Vas Joint System Blounts KAFO (www.AnatomicalConceptsInc.com).
At the age of 4 + 4, six months post fitting of VVASBK, the radiograph (figure a -5) obtained showed significant improvement in comparison to previous orthotic management with the DSUK. Follow up at 5 +1 years of age again showed continued improvement in achieving more normal age appropriate skeletal alignment (figure a -6).
Patient B is a non obese Caucasian male whose initial radiograph confirmed the diagnosis of Blounts disease, with varus thrust. He was referred to the local orthotist for measurement and fabrication. At 1 + 11 years of age, radiographic evidence of deformity progressing was confirmed (figure b -1). He was fitted with VVASBK and seen for follow up four months post fitting at the age of 2 + 3, when a radiograph was obtained showing improvement in skeletal alignment (figure b -2). The radiograph completed at ten months from initial fitting showed a continual overall improvement in the skeletal alignment (figure b -3). It was decided by the team treating patient B to discontinue the VVASBK at this time and follow up in nine months. Radiograph (figure b -4) was obtained at the nineteen month follow up (wore VVASBK for ten months then discontinued for nine months) validating successful treatment using the VVASBK.
Traditional orthotic management with drop lock or solid upright designs have been successfully used as a treatment method for Blounts disease and other bowing deformities in the lower limb. Success rate has ranged from 50% to 90% without recurrence. With traditional single solid upright treatment, of those followed up after 5.9 years and with unilateral involvement, 6% went on to surgery while 70% of those bilaterally involved went on to surgery2. Paramount to maximizing outcomes is the determination of correct etiology, age appropriateness, genetics, stature, lateral thrust, radiographic evidence and documented progression. Once identified, most often the success is linked to the individual design selected itself and the experience of the team managing the patient. Additionally experience of the treating orthotist, compliance by the family and physicians input play a major role in the ultimate outcome. The results of patient B's treatment using the VVASBK demonstrates the effectiveness of this new design following accepted protocols established in recommending orthotic management in the infantile patient. Evidence gathered from the results of patient A not only confirms the success of the VVASBK but further validates that patients with Blounts disease can be treated not only much later in the infantile stage but successfully in the late onset stage as well. Additionally further success is demonstrated in patient A's case study for treating those who are considered obese and or have bilateral involvement. Obese and bilateral involvement are two contraindications for the use of orthotic management. This study confirms that the unique design of the V-Vas Joint System, associated features of the VVASBK and the significant improvement in compliance associated with this specific design has resulted in the optimal outcomes in treatment of the typical and atypical patients with Blounts disease. Further study with a larger number of patients and long term study will be necessary to add validity to the findings of this small study. The VVASBK is a new and effective way of noninvasively managing traditional and non traditional lower extremity bowing deformities and should be a primary consideration when treating such deformities in order to achieve good correction and improve patient comfort and compliance.
Ongoing studies are showing successful treatment with the VVASBK on patients diagnosed with genu valgum deformities, hemiepiphysiodesis with varus thrust and similar compliance in the obese adolescent Blount's disease patient as found in this study.
Arie (Bud) Bronkhorst, CO, FAAOP; Hanger Prosthetics and Orthotics, Austin, Texas. For his extraordinary dedication to superior patient care and application of cutting edge technology.
Dell Children's Hospital, Austin Texas. For there continued support in bringing innovative technology to the patient.
Adam Engstrom, board eligible orthotist; Hanger Prosthetics and Orthotics, Boardman, Ohio. For his ability to focus on superior patient outcomes.
Dr. Sheryl Matasar-Handler MD, Akron Children's Hospital, Boardman, Ohio; for her dedicated support and contributions to this research.
Akron Children's Hospital, Akron, Ohio; for their continued dedication to optimal patient outcomes and associated research.
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