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 Table of Contents  
Year : 2020  |  Volume : 12  |  Issue : 1  |  Page : 23-30

Long-term study of functional outcomes of floating knee injuries

Department of Orthopaedics, Sri Aurobindo Medical College and PG Institute, Indore, Madhya Pradesh, India

Date of Submission11-Feb-2020
Date of Acceptance20-Apr-2020
Date of Web Publication26-Jun-2020

Correspondence Address:
Dr. Adhir Jain
Department of Orthopaedics, Sri Aurobindo Medical College and PG Institute, Ujjain Highway, Indore - 452 015, Madhya Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jotr.jotr_10_20

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Background: Floating knee injuries are commonly occurring fractures in the high-velocity trauma. The mode of injury is usually due to road traffic accidents. Over the years, there have been many studies which have shown results of various conservative, external fixation, and finally, internal fixation treatment all over the world. However, still, there is very less work on long-term outcome-based analysis of functional outcomes of floating knee injuries. The aim of the study was to assess the long-term functional outcome of operated patients of floating knee injuries. Materials and Methods: A total of 30 patients with floating knee injuries who were undergone surgical fixation by any means were included in ths study. The study was done at a tertiary teaching institute and hospital from April 2013 to May 2019. The patients were followed up at 6 weeks, 6 months, 1 year, and 5 years (final) after the surgery. The assessment of pain, functional activity, walking ability, and range of motion was assessed by Karlstrom and Olerud criteria at 6 months, 1 year, and 5 years. Results: We included 30 patients diagnosed with floating knee injuries in our study with a mean age of 40.83 years (18–75 years range) and a female-to-male ratio of 5:1 with 25 males (83.3%) and 5 females (16.7%). All the patients underwent fixation under spinal/epidural anesthesia/general anesthesia. Fifteen patients were Fraser type 1, 4 patients were Fraser type 2A, 5 patients were Fraser type 2B, and 6 patients were Fraser type 2C. Average operating time was 120 ± 55 min. Right-sided involvement was more common (17 patients) than the left side (13 patients). The good/excellent outcome was found in 63.4% of the cases. Patients with age <40 years had better prognosis as compared with patients of >40 years of age (df = 12, P = 0.014). Final outcomes had no difference in males as compared to females at 5 years postoperatively (df = 4, P = 0.265). Complications such as knee stiffness, infection, malunion, delayed union, and nonunion were also encountered. Conclusion: Surgical fixation is an effective treatment for floating knee injuries worldwide. On long-term follow-up of patients treated surgically, the functional and radiological outcomes were good with few complications rates.

Keywords: Floating knee injuries, functional outcome, Karlstrom and Olerud

How to cite this article:
Shukla R, Jain A, Jain RK. Long-term study of functional outcomes of floating knee injuries. J Orthop Traumatol Rehabil 2020;12:23-30

How to cite this URL:
Shukla R, Jain A, Jain RK. Long-term study of functional outcomes of floating knee injuries. J Orthop Traumatol Rehabil [serial online] 2020 [cited 2022 Aug 10];12:23-30. Available from: https://www.jotr.in/text.asp?2020/12/1/23/287704

  Introduction Top

The floating knee is defined as ipsilateral fractures of the femur and tibia causing flail knee joint. Floating knee injuries can include a combination of diaphyseal, metaphyseal, and intra-articular[1],[2] fractures of the tibia and femur. The term “Floating Knee” was labeled by McBryde and Blake[3] in the year 1974 to draw the attention from the skeletal plane of the lower limb to the vascular plane of knee where complications are more severe and common also. As a result of increasing industrialization and increase in number of vehicles floating, knee injuries are becoming more common as these fractures are caused by high-energy trauma, primarily involving high-velocity motor vehicle accidents/road traffic accidents (RTAs). Due to the association of many complications such as compartment syndrome, vascular injuries, infection, union-related difficulties, ligaments, meniscal injuries, and complex nature of injury, the management of floating knee injuries is a challenging problem. Most often, floating knee injuries are compound and associated with severe damage of soft tissues. Life-threatening head injuries, injuries to the spinal cord, and thoracic and abdominal (visceral) injuries are also seen. For best clinical and functional outcome, early surgical stabilization of both the femur and tibia fractures along with early rehabilitation of the patient is necessary. For the accomplishment of good/excellent functional outcome, treatment planning for each and every type of fracture in the extremity should be considered exclusively, the effect of that decision must be considered in the light of overall injury status of the entire extremity and general condition of the patient. When the fractures are diaphyseal or extra-articular, the results will be better and the complications will be less than compared to intra-articular fractures. The main aim of the early internal fixation of both the femur and tibia in floating knee injuries is to obtain the union of the fractures in the anatomical reduction position with the maximal functional outcome of the patient and to reduce delayed union, nonunion, infection, and knee stiffness/arthritis-like complications.

Nowadays, soft-tissue envelope and preservation are paid more attention. Soft tissue friendly approaches and minimally invasive techniques have improved the overall results of functional outcome. Treatment of these floating knee injuries using minimally invasive techniques minimizes soft-tissue injury and damage to vascular integrity of fracture fragments. Newer techniques had the advantages of reducing the articular surface, aligning the limb, and mobilizing early after injury with less encumbering external devices. Fraser et al.[4] in the year 1978 suggested a classification system for the floating knee injuries in adults, which is also most widely used. In the year 1977, Karlstorm and Olerud,[5] in a review of 32 patients, focused on the importance of rigid fixation of both the fractures in floating knee injuries. Karlstorm and Olerud also gave a prognostic system to assess the functional results following floating knee injuries.

  Materials and Methods Top

This study was performed from April 2013 to May 2019 in patients coming to our hospital with floating knee injuries in our institute which is one of the biggest tertiary care centers in the Central region. Patients with any other associated fractures and compound injuries were also included in the study. Written informed consent was obtained from all the patients. Few of the patients were lost to follow-up. Three patients died due to complications resulting from polytrauma and pathological fractures were excluded from the study. Thus, at last, 30 patients who had floating knee injuries managed operatively were included in the analysis.

All the patients coming to the outpatient department and emergency who sustained fractures of the femur and tibia following RTAs/run over injury were considered to be a part of the study. All the patients underwent clinical and radiographic examination. The fractures were classified according to the Fraser[4] classification system based on the X-ray images. For open fractures, Gustilo–Anderson classification was used. Patients of floating knee injuries were admitted to the ward. A detailed history of all patients was taken and recorded in inpatient files. All patients were assessed clinically, and also, assessment was done for anteroposterior and mediolateral ligamentous laxity. The preoperative medical evaluation of all patients was done to prevent potential complications that can be life-threatening or limb-threatening. All patients were due to RTA.

On arrival, patients were resuscitated according to the Advanced trauma life support (ATLS) protocol (maintenance of airway with cervical spine control, breathing, and circulation). The general condition of the patient was assessed with regard to hypovolemia, associated orthopedic, or other systemic injuries. Any systemic injury if present was given priority in treatment.

Fracture femur and tibia were immobilized with Thomas splint. All patients received analgesics and antibiotics intravenously (IV). In case of open fractures, immediate debridement and external fixator were applied under anesthesia. When the wound was clean cut and not contaminated, primary closure was done after proper debridement. When wound size was large with skin loss, secondary closure, skin grafting, or local flaps were done.

Radiographic assessment

Standard guidelines were utilized to get thigh, knee, and leg radiographs in anteroposterior view and lateral view. Respective essential scans of other body parts were taken to rule out other injuries. In certain cases, computed tomography (CT) scans were also taken to have a better analysis of fracture geometry. Furthermoe, X-ray and CT scan were screened for bony avulsion fractures of anterior cruciate ligament, posterior cruciate ligament, lateral collateral ligament, and medial collateral ligament.

Preoperative protocol

Preoperative Medical Evaluation: All patients were investigated according to our routine preoperative protocol which includes blood reports (such as complete blood count [CBC], HIV, HbsAg, blood group test, serum electrolytes, blood glucose level, and renal function tests), electrocardiogram, and chest X-rays. Necessary and adequate management was given for those associated with medical problems such as anemia, diabetes, hypertension, ischemic heart disease, chronic obstructive pulmonary disease, and asthma that were evaluated and treated before taking them to surgery. A strict preoperative protocol was followed which included obtaining pre-anesthetic checkup and various required clearances, and part preparation. Arrangement of adequate blood was done, if part of polytrauma or anemia. Keeping patient nil by the mouth from 6 hours prior to surgery. Written and informed consent taken. Other required consents such as high-risk consent. Patients as well as the attendants were explained about the surgery and its risk factors and written consent for the surgery obatined from all patients. Proper planning and preparation should be taken according to the analyzed plan, i.e., if something was extra required, then obtaining it's prior consent, implant selection, etc. IV antibiotics and tetanus immunization were given an hour before the surgery.

Operative procedure

All patients after thorough preoperative evaluation were taken up for surgery by the same surgical team under general or spinal or epidural anesthesia. Tourniquet was applied (wherever is necessary) at the thigh region and sterile preparation was done from thighs to toes and draped. Intramedullary interlocking nailing was done wherever possible. Anatomical reduction was achieved for intra-articular fractures and fixed with plates and screws.

Immediate postoperative

  • Vitals charting (including blood pressure, temperature, pulse rate, and respiratory rate)
  • Input and output charting
  • Distal neurovascular examination
  • Postoperative analgesia
  • Watch out for soakage
  • Postoperative antibiotics for 7–10 days (depending on nature of wound)
  • Foot end elevation (as the surgeries are performed under spinal Anesthesia).
  • Postoperative X-ray was done preferably the next day (or when the patient is stable).

Early postoperative

  • Dressings of wound: As a routine on 2nd and 5th postoperative days (PODs)
  • Routine CBC on 2nd POD
  • Suture removal on 14th POD (or as per the condition of a wound)
  • Physiotherapy.

Physiotherapy following fixation and early range of motion exercises were initiated depending on the consciousness level, hemodynamic condition, pain status, and associated injuries. For cases with poor Glasgow coma score, passive range of motion exercises to the ankle and toe and calf muscle squeezing was done to prevent deep venous thrombosis. Chest physiotherapy was given for preventing the respiratory-related complications. For conscious and hemodynamically stable patients, active range of motion exercises was started to the ankle and toe on 1st POD. If a patient was stable, then he//she mobilized with nonweight-bearing walking with the help of a walker on POD 1 or 2. Active knee range of motion in-bed and high sitting permitted up to 90° for initial 2–3 weeks (depending on fracture pattern and stability of fixation). Usually after 3 weeks full range of motion exercises of knee joint started mainly focusing on static quadriceps and dynamic quadriceps exercises. Partial weight bearing mobilization done after 6–8 weeks, once the X rays show sufficient callus at the fracture site. Further full weight-bearing mobilization was done depending on follow up X-rays and clinical findings.

Evaluation criteria

The assessment of pain, functional activity, walking ability, and range of motion was assessed using Karlstorm and Olerud criteria [Table 1].[5] Age-related functional impairments were also taken in consideration. All the complications occurring in patients were recorded such as knee stiffness, pulmonary embolism, infection, malunion, nonunion, and delayed union. Patients were followed-up at 6 weeks, 3 months, and 6 months and then at 1 and 2 years and final follow-up at 5 years postoperatively. The Karlstorm and Olerud scoring [Table 2] at 6 months and 1, 2, and 5 years postoperatively were taken into consideration for the statistical analysis.
Table 1: Karlstrom and Olerud criteria

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Table 2: Scoring in Karlstrom and Olerud criteria

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Statistical analysis

The data were initially collected in the customized pro forma and then transferred into Microsoft Excel for the analysis. Minitab version 17.0 (Minitab, LLC Headquartered in State College, Pennsylvania, USA) was used for calculating the P values. The descriptive statistics were presented in the form of numbers and percentages. Comparison of mean values between two-time intervals for the same demographic variables was done using paired t-test. Association between two nonparametric variables was done using the Pearson coefficient of correlation. P < 0.05 was taken as statistically significant.

  Results Top

A total of 30 study patients with a mean age of 40.83 years (18–75 years range) [Table 3] with male – 25 (83.3%) and female – 5 (16.7%) were included during the study period. As per Fraser type 1, there were 15 (50.0%) fractures; in type 2A, there were 4 (13.3%) fractures; in type 2B, there were 5 (16.7%) fractures; and in type 2C, there were 6 (20.0%) fractures. Majority of the fractures were in Fraser type 1, followed by Fraser type 2C. The average operating time was 120 ± 55 min, more in obese, open fractures, and with type 2C, 2B fractures. Left-sided involvement was in 13 patients (43.3%) and right-sided involvement was in 17 patients (56.7%) [Table 4].
Table 3: Age-wise distribution

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Table 4: Patient demographics

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The mean time of radiological union was 15.93 ± 1.53 weeks for the femur, and for the tibia, it was 17.73 ± 1.51 weeks. There was a significant improvement in pain, functional activities, walking ability, and range of motion at 5 years when compared with 6 months and 1 year [Table 5] and [Table 6].
Table 5: Comparison of Karlstrom and Olerud grading at different time intervals

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Table 6: Comparison of mean Karlstrom and Olerud score at different time intervals

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We compared and associated the scores of different age groups (group 1 with 18–20 years of age, group 2 between 21 and 40 age, group 3 between 41 and 60 years of age, and group 4 between 61 and 75 years of age). We observed that Pearson Chi-square value was 25.239, df = 12, and P = 0.014, which was statistically significant [Table 7].
Table 7: Association between age and Karlstrom and Olerud Grading at final follow-up

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Associated comorbidities such as diabetes mellitus and hypertension have no significant impact on 5-year functional outcome.

The association between sex and Karlstrom and Olerud grading at final follow- up is shown [Table 8].
Table 8: Association between sex and Karlstrom and Olerud grading at final follow-up

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Final functional outcomes for Fraser type 1 [Figure 1] and [Figure 2], 2A [Figure 3], 2B type [Figure 4], and [Figure 2]C [Figure 5] had 80%, 25%, 60%, and 50% of good/excellent scores at 5 years postoperatively, respectively [Table 9].
Figure 1:Radiograph showing Segmental fracture of tibia with shaft femur fracture with excellent score at the final follow-up of 5 years postoperatively

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Figure 2:Radiograph showing segmental fracture of femur and shaft tibia fracture with good score at the final follow-up of 5 years postoperatively

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Figure 3:Radiograph showing Fraser type 2A with moderate score at 1 year post-operatively

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Figure 4:Radiograph showing Fraser type 2B

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Figure 5:Radiograph showing Fraser type 2C with femur open GA 3A, with poor follow-up

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Table 9: Good/excellent results at final follow-up according to Fraser classification type

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Complications occurred in 7 patients of total 30 (23.3%) including one infection, two knee stiffness, one pulmonary embolism, one with nonunion [Figure 6], one with mal-union, and one with delayed union [Table 10].
Figure 6:Radiograph showing nonunion femur with malunion of Tibia

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Table 10: Surgical complications

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  Discussion Top

With increasing trends in RTAs, patients with multiple system involvements are increasing day by day. During the course of treatment of such patients, the two most important factors need consideration. First is a systemic injury with body response to injury complicating the situation and second is problem-associated concomitant injuries. The analysis of the results was made in terms of age of the patient, sex distribution, side of injury, mode of injury, open/closed fracture, classification of fractures, definitive fracture fixation method, associated injuries, number of surgeries, complications, revision surgery, fracture union time, and the functional outcome using Karlstorm and Olerud criteria.

This is an observational, both prospective and retrospective, study of 30 patients with age ranging from 18 to 75 years.

In our study, the most common mode of injury was RTA (93.3%). Our findings are comparable to the studies made by Nouraei et al.,[6] Feron et al.,[7] Andrade-Silva et al.,[8] and Kulkarni et al.[9] There were 25 (83.3%) closed femur fractures, while 2 (6.7%) were open Gustilo-Anderson (GA) 1 fractures, 1 (3.3%) was open GA 3A fracture, 1 (3.3%) was open GA 3B fracture, and 1 (3.3%) was open GA 3C fracture. There were 24 (80.0%) closed tibia fractures, while 3 (10.0%) were open GA2 fractures, and 3 (10.0%) were open GA 3A fractures. Our findings are comparable to other studies made by Kao et al.,[10] Ran et al.,[11] Andrade-Silva et al.,[8] Chavda et al.,[12] Rollo et al.,[13] and Rollo et al.[13] and they reported that in the study of 224 patients of floating knee injuries, they had 57.14% of open fractures. Ran et al.,[11] in 28 patients, the study had 28.57% of open tibia fractures and 21.42% of open femur fractures. Andrade-Silva et al.[8] had 14 patients of open fracture of 21 sample size in a study related to floating knee injuries, in which closed femur and tibia were 7, closed femur and open tibia were 9, open femur and closed tibia were 2, and open femur and tibia were 3. In our series, Fraser type 1, there were 15 (50.0%) fractures; in type 2A, there were 4 (13.3%) fractures; in type 2B, there were 5 (16.7%) fractures; and in type 2C, there were 6 (20.0%) fractures. Majority of the fractures were in Fraser type 1, followed by Fraser type 2C. Varying degrees of incidences of various fracture types have been reported in other studies [Table 11]. The most common associated injury was contralateral shaft femur fracture seen in 3 (10.0%) patients and head injury seen in 3 (10.0%) patients, then fracture distal end radius seen in 2 (6.7%) patients; and fracture second metatarsal; fracture Both Bone Forearm (BBFA); fracture shaft humerus; abdominal trauma; intertrochanteric femur fracture; ligament injury; and vascular injury were seen in 1 (3.3%) patient each (note: some patients had more than one associated injuries). Associated injuries were seen in 40% of the cases in our study. There were varying percentages of associated injuries with other studies done by Feron et al.,[7] Kulkarni et al.,[9] Chavda et al.,[12] and Demirtas et al.[14] We had also compared the complications with various studies [Table 12]. For femur and tibia fractures, we had the mean union time of 15.93 ± 1.53 and 17.73 ± 1.51 weeks, respectively. Our findings are comparable to the studies made by Kulkarni et al.[9] and Chavda et al.,[12]
Table 11: Comparison of distribution of patients according to Fraser type in various studies

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Table 12: Comparison of complications with various literatures

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Kulkarni et al.[9] in 90 cases of floating knee injuries had mean union time of 42 ± 29.48 and 38.08 ± 26.4 weeks in femur and tibia fractures, respectively, with wide range. Chavda et al.[12] in a study of 52 patients of floating knee injuries reported that they had mean union time of 22 weeks with a range of 16-32 weeks. Finally, the percentage of good/excellent functional outcomes at the final follow-up was comparable with other studies also [Table 13]. Furthermore, it was comparable with fracture pattern in other studies done by Kulkarni et al. [Table 14]. In comparison with other studies, our outcomes are similar, but we had less complication. No other study has documented long-term follow-up results in the management of Floating Knee Injuries.
Table 13: Comparison of percentage of good/excellent results of our study with various studies

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Table 14: Comparison of good/excellent results at final follow-up of our study with various studies according to Fraser classification type

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  Conclusion Top

The following could be drawn from the surgical management of floating knee injuries: good/excellent functional outcome depends on the following factors – bone comminution, articular involvement, and nature of the fracture whether open or closed. In-depth wound debridement with early stabilization and mobilization offers good/excellent functional outcomes in the management of floating knee injury. Initial external fixator application is a poor prognostic factor of floating knee injuries outcome. Special attention should be given to better the initial diagnosis of associated ligamentous injury. The timing of fracture fixation depends on various factors; however, first femoral fixation is recommended with an exception in few cases (early tibia fixation sometimes facilitates the reduction and fixation of a complex distal femur fracture). Nailing for both tibia and femur remains the best treatment in Fraser type I floating knee. In conclusion, the best results are obtained when the operative method results in stable fixation. Fixation should be always be followed by early physiotherapy. The rehabilitation program plays an important role in functional outcomes of a floating knee injury. The main aim of surgical management includes accurate reconstruction of the articular surface, stable fixation of fracture, and restoration of concomitant soft-tissue injuries allowing an early range of movement to get better functional outcomes. Hence, the floating knee is a complex injury; the rate of complications associated with the floating knee remains high, regardless of the performed management. Early surgical fixation of both femur and tibia gives good functional outcomes.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Lundy DW, Johnson KD. Floating knee injuries: Ipsilateral fractures of the femur and tibia. J Am Acad Orthop Surg 2001;9:238-45.  Back to cited text no. 1
Jeong GK, Pettrone SK, Liporace FA, Meere PA. Floating total knee: Ipsilateral periprosthetic fractures of the distal femur and proximal tibia after total knee arthroplasty. J Arthroplasty 2006;21:138-40.  Back to cited text no. 2
McBryde A Jr., Blake R. The floating knee, ipsilateral fractures of femur and tibia. JBJS 1974;56:1309.  Back to cited text no. 3
Fraser RD, Hunter GA, Waddell JP. Ipsilateral fracture of the femur and tibia. J Bone Joint Surg Br 1978;60-B: 510-5.  Back to cited text no. 4
Karlstrom G, Olerud S. Ipsilateral fractures of femur and tibia. J Bone Joint Surg 1977;9:240-3.  Back to cited text no. 5
Nouraei MH, Hosseini A, Zarezadeh A, Zahiri M. Floating knee injuries: Results of treatment and outcomes. J Res Med Sci 2013;18:1087-91.  Back to cited text no. 6
Feron JM, Bonnevialle P, Pietu G, Jacquot1 F. Traumatic floating knee: A review of a multi-centric series of 172 cases in adult. Open Orthop J 2015;Suppl 1 M11:356-60.  Back to cited text no. 7
Andrade-Silva FB, Carvalho A, Mansano C, Giese A, Leonhardt MC, Barbosa D, et al. Functional results and isokinetic muscle strength in patients with Fraser type I floating knee treated with internal fixation. Injury 2017;48 Suppl 4:S2-5.  Back to cited text no. 8
Kulkarni MS, Aroor MN, Vijayan S, Shetty S, Tripathy SK, Rao SK. Variables affecting functional outcome in floating knee injuries. Injury 2018;49:1594-601.  Back to cited text no. 9
Kao FC, Tu YK, Hsu KY, Su JY, Yen CY, Chou MC. Floating knee injuries: A high complication rate. Orthopedics 2010;33:14.  Back to cited text no. 10
Ran T, Hua X, Zhenyu Z, Yue L, Youhua W, Yi C, et al. Floating knee: A modified Fraser's classification and the results of a series of 28 cases. Injury 2013;44:1033-42.  Back to cited text no. 11
Chavda AG, Lil NA, Patel PR. An approach to floating knee injury in Indian Population: An analysis of 52 patients. Indian J Orthop 2018;52:631-7.  Back to cited text no. 12
[PUBMED]  [Full text]  
Rollo G, Falzarano G, Ronga M, Bisaccia M, Grubor P, Erasmo R, et al. Challenges in the management of floating knee injuries: Results of treatment and outcomes of 224 consecutive cases in 10 years. Injury 2019;50:453-61.  Back to cited text no. 13
Demirtas A, Azboy I, Alemdar C, Gem M, Ozkul E, Bulut M, et al. Functional outcomes and quality of life in adult ipsilateral femur and tibia fractures. J Orthop Translat 2019;16:53-61.  Back to cited text no. 14


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10], [Table 11], [Table 12], [Table 13], [Table 14]


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