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Department of Orthopedic Surgery, Texas Children’s Hospital, Houston, 17580 Interstate 45 South, the Woodlands, Texas, 77384, USABaylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, Texas, USA
Tibial tubercle/tuberosity fractures are rare injuries in young patients accounting for less than one percent of physeal fractures. Bilateral simultaneous fractures are even rarer, with only a few case reports in literature. The purpose of our study was to describe the largest case series of bilateral simultaneous tibial tuberosity avulsion fractures and compare it with unilateral fractures. We also wanted to compare our bilateral fractures case series with all the cases reported in the last 65 years.
Methods
IRB approved retrospective study involving patients under age 18 years with tibial tuberosity avulsion fractures. Bilateral simultaneous fractures were compared to a unilateral group including demographic data, mechanism of injury, clinical exam findings, complication rates, and outcomes including return to function. Statistical analysis was performed using Mann-Whitney and Fisher Exact tests to compare the different groups.
Results
138 patients (131 males, 7 females) from a tertiary children’s hospital between 2012 and 2019 with tibial tuberosity avulsion fractures were included. 11 bilateral simultaneous fractures (BL Group) were identified and compared to age matched cohort from the 127 unilateral fracture patients (UL group). There was no significant difference found in BMI, height, weight, age, sex, mechanism of injury, return to functional range of motion, and return to sports between the groups. 7/11 (63%) of the patients in the BL group who sustained simultaneous fractures had to be home bound and could not attend school for an average of 8.3 weeks. There was a higher rate of complications in the BL group (63.3%) compared to the UL group (21.1%), which was statistically significant. The most common complications in the bilateral group were hardware removal and wound dehiscence.
Conclusion
This first case series comparing unilateral versus bilateral simultaneous tibial tuberosity avulsion fractures suggests that the final outcomes of the two groups are similar, however it shows a significantly higher complication rate and hardware removal rate in the BL group. This study is also the first to highlight the significant initial morbidity in the BL fracture group with issues with regards to early mobility and loss of school-days. Keeping in mind the profound initial impact the bilateral injury poses to the patient; surgeons can possibly plan for rigid fixation for early mobilization to better prepare bilateral fracture patients for the early post-operative recovery process.
as the proximal tibial physis is closing. This fracture is often associated with a sports related mechanism of injury such as jumping and the most frequently associated sports are basketball and high jump.
bilateral tibial tuberosity avulsion fractures are exceedingly rare, with less than 40 total cases described primarily as single patient case reports in literature in the past 65 years.
Surgical fixation of bilateral simultaneous avulsion fractures of the proximal tibia in a 12-year-old with history of conservatively managed unilateral tibial avulsion fracture.
Due to limited literature on tibial tuberosity fractures, it has been difficult to determine associated injuries, morbidity, appropriate treatment, complications, and outcomes of these fractures.
Our study reviews the largest case series of bilateral tibial tuberosity avulsion fractures reported to date, comparing this fracture to a unilateral fracture group. We also wanted to compare our case series with all the cases reported in the last 65 years with a literature search.
2. Materials and methods
This was an IRB approved retrospective study which included patients under the age of 18 years with tibial tuberosity avulsion fractures after searching Electronic Medical Records (EMR) from a tertiary children’s hospital between 2012 and 2019. Patients above the age of 18 years and with other pre-existing bone conditions like osteogenesis imperfecta were excluded. Patients were divided into two groups, unilateral group (UL) and bilateral group (BL). The two groups were analyzed for data including age, sex, weight, height, BMI, mechanism of injury, clinical exam findings including knee range of motion, length of follow up, complication rates, and outcomes including return to function and sports. Radiographs were reviewed to classify and compare all fractures using the modified Ogden Classification. Clinical notes and operative reports were reviewed to determine type of surgery and fixation that was used. All BL group patients were treated using standard anterior approach with a midline longitudinal incision centered over the tuberosity for open reduction and internal fixation (ORIF). The interposed periosteum was removed, fracture reduced with knee extended and fixed with multiple cannulated screws, partially or fully threaded (size 4 mm–6.5 mm) to achieve compression, depending on surgeon preference. Patients were non-weight bearing for initial 6 weeks and knee range of motion and quadriceps strengthening were initiated at 6 weeks post surgery. Using SPSS software, statistical analysis was performed with Mann-Whitney and Fisher Exact tests to the compare the different groups.
Literature search was performed for all bilateral simultaneous tibial tuberosity fractures that had occurred since first described in 1955 and were analyzed(Table 1).
Table 1Review of all previous case reports on bilateral fractures in literature.
138 patients with 150 tibial tuberosity fractures (Fig. 1) were divided into two groups: 128 unilateral fractures in 127 patients (UL group) and 22 bilateral simultaneous fractures in 11 patients (BL group). The UL group included one patient who sustained bilateral sequential fractures separated by seven months and for the purposes of our study was treated as two separate unilateral fractures.
Fig. 1Tibial tuberosity avulsion fracture left and right knee AP and lateral views.
Table 2 compares the characteristics of UL group and BL group. The average age at the time of injury, height, weight and BMI did not show statistically significant difference between UL group and BL group. Regarding mechanism of injury both groups were primarily sports related with basketball being the most commonly implicated sport.
Table 2Comparison of UL and BL group characteristics.
All patient’s radiographs were classified according to the Modified Ogden Classification. There were 150 fractures in 138 subjects for the entire cohort. In the UL group (128 fractures), the most common fracture type was IIIB. There were 7 type IA, 29 IB, 8 IIA, 13 IIB, 16 IIIA, 38 IIIB, and 17 type IV (Fig. 2). There were 22 fractures in 11 patients in the BL group, and the most common fracture pattern was IIIB. There was 1 type IA, 5 IB, 1 IIA, 2 IIB, 3 IIIA, 6 IIIB, and 4 type IV fractures (Fig. 3). This data was compared to the fracture classification for all prior case reports. There were 34 prior cases found in literature for a total of 68 fractures. Of those, 62 had a listed classification. The most common fracture type was Type III. There were four (6%) Type I fractures, 12 (19%) Type II fractures, 34 (57%) Type III fractures, 10 (16%) Type IV, one type V case (2%), and one fracture listed as Type II/III (Fig. 4).
In reviewing the fracture patterns in the BL group from our cohort, it was found that 63.6% (7 of 11) had a more severe injury on one side compared to the other.
When evaluating the initial impact of the injury, all patients who sustained a bilateral simultaneous injury required use of a wheelchair. Their mobility was significantly limited as both lower extremities had to be immobilized in a hinged-knee brace locked in extension and remain non-weight bearing for an extended period of time, average 6.7 weeks (range 5–12 weeks). Also 7/11 (63%) of the patients in the BL group had to be home bound and could not attend school for an average of 8.3 weeks (range 2–20 weeks).
When comparing clinical outcomes of the UL and BL groups at mean follow-up of 9 months, both had return to near-full range of motion. UL group average extension reported to be 0.41° and flexion 131.7°. BL group range of motion reported to be average 0.45° extension and 131.4° flexion. Return to previous activity for UL group was average 22.6 weeks and BL group 28.5 weeks which was not significantly different. No extension lag, delayed union or non-union was reported in any of the groups (Fig. 5, Fig. 6).
Fig. 5Tibial tuberosity avulsion fracture both knees immediately post-op. after screw fixation.
In the UL group 27/128 (21.1%) had complications as compared to a 63.6% (7/11) for the BL group. The most common complication for both groups was hardware removal. In the UL group 21/128 (16.4%) underwent hardware removal and 5/11 (45.5%) for the BL group. The higher rate of complications in the BL group compared to the UL group was statistically significant. Other complications that occurred in the BL group included two patients who developed post-operative wound dehiscence and one patient who developed a leg length discrepancy and genu valgum which was treated with a femoral osteotomy. One patient in the BL group required hardware removal due to development of an exostosis. (Table 3).
Avulsion fractures of the tibial tuberosity are an uncommon injury which occur in young patients during a vulnerable period when the physis is undergoing physiologic changes that weaken its ability to resist tension loading.
These patients are more susceptible to injury as adolescent males have strong quadriceps muscles and the physis is in a vulnerable state while it is undergoing fusion. The mechanism is described as occurring either from the take-off or landing of a jump. During take-off, the strong quadriceps muscle contracts as the knee extends or upon landing, the knee rapidly flexes as the quadriceps contracts.
When the amount of force applied by the patellar tendon exceeds the strength of the physis, it succumbs to avulsion injury. The injury was initially classified in 1976 by Watson-Jones into 3 types.
Ryu and Debenham further classified the fracture to include a type IV when the entire proximal tibial epiphysis is avulsed and McKoy and Stanitsky suggested a Type V forming a Y fracture pattern.
The modality for treatment is based on the degree of displacement. Minimally displaced fractures may be treated using closed reduction and with cast immobilization. Displaced fractures may be treated either closed or with open reduction and internal fixation.
It is important to consider the risk of surgery involving the tibial tuberosity as there is the possibility of complications resulting in development of leg length discrepancy, angular deformity, or premature closure of the growth plate.
; injuries in both our groups were primarily sports related. Basketball was the most common sport implicated in the bilateral fracture cohort, which is consistent with literature.
The primary modality for treatment listed in the case reports in literature was ORIF. 57/68 fractures (86.8%) as compared to our study where all BL group patients were treated with ORIF with screws. In previous case reports, one case, two fractures were treated with casting only,
Return to sports (RTS) for bilateral fractures (28.5 weeks in our study) has not yet been reported for bilateral cases in the case reports in literature.
The complication rate was higher for the BL group, and we compared this with the percentage of complications in the case reports in literature. Of the 34 prior reported cases, 11 were listed as having a complication (32.4%), and five of those cases were hardware removal (45.5%).
Surgical fixation of bilateral simultaneous avulsion fractures of the proximal tibia in a 12-year-old with history of conservatively managed unilateral tibial avulsion fracture.
For the purposes of comparison, hardware removal was included as a complication without regard to reason for removal. Orthopedic surgeons can possibly plan to countersink the screw head to avoid discomfort due to screw prominence and obviate the need for hardware removal.
When evaluating the initial impact of the injury, it is important to note that all patients who sustained a bilateral simultaneous injury required use of a wheel chair as both lower extremities had to be immobilized and remain non-weight bearing. Their mobility was significantly limited for an extended period of time; this initial morbidity has not been addressed in any of the previous literature. Also, majority of the patients in the BL group were home-bound and could not attend school for an average of greater than 2 months. None of the prior case reports have emphasized the extreme impact this injury can have with regards to initial morbidity and mobility issues. The surgeons can plan for more rigid fixation for early mobilization of the patients to possibly minimize this impact.
Limitations of our study include a small number of patients and retrospective data collection from a single institute. However, this being a rare fracture, our case series is much larger than the only previous case series which had 3 patients.
Multicenter data collection can help to shed more light on this rare fracture in the future.
5. Conclusion
The first study comparing bilateral simultaneous tibial tubercle avulsion fractures show similar demographics and final outcomes to unilateral fractures. The detrimental impact this injury can have with regards to initial morbidity due to mobility issues and higher complication rate should be kept in mind for bilateral simultaneous fractures.
Sources of support (if applicable)
None.
Institutional review board statement
The study was reviewed and approved by the Baylor College of Medicine Institutional Review Board.
Informed consent statement
No consent was required as it was a retrospective chart review.
Statement of equal authors’ contribution
We provide assurance that each author fulfills authorship criteria based on the substantial contributions to the study.
Authors’ contribution
Indranil Kushare: Responsible for initiation of methodology, data collection, manuscript writing, and final approval of the manuscript. Nicole Wunderlich: Involved in investigation and methodology, data acquisition, manuscript reviewing and editing and final approval of the manuscript. Darius Dranginis: Involved in literature review, investigation and methodology, data acquisition manuscript writing and editing and final approval of the manuscript.
Declaration of competing interest
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. No conflict of interest is to be declared.
References
Fernandez Fernandez F.
Eberhardt O.
Schröter S.
Wirth T.
Ihle C.
Bilateral tibial tubercle avulsion fractures in children - clinical results of a rare fracture.
Surgical fixation of bilateral simultaneous avulsion fractures of the proximal tibia in a 12-year-old with history of conservatively managed unilateral tibial avulsion fracture.
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