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Floating Knee Workup

  • Author: Srinivasa Vidyadhara, MBBS, MS, DNB; Chief Editor: Carlos J Lavernia, MD  more...
 
Updated: Jan 15, 2014
 

Imaging Studies

See the list below:

  • Radiography
    • Obtain anteroposterior and lateral views of the femur and tibia, including views of the joint above and below.
    • Order radiographs showing the pelvis and both hips.
    • Obtain anteroposterior and lateral views of the affected knee.
  • Magnetic resonance imaging
    • MRI of the knee joint is advocated in patients with suspected injuries to the intra- or extra-articular ligaments.
    • MRI findings may in help in planning management of ligamentous injuries.
  • Computed tomography scanning: CT scans of the metaphyseal fractures may be useful for understanding the 3-dimensionsal configuration of the fracture fragments.
  • Other imaging studies: Generalized radiologic screening of suspected skeletal injuries may be undertaken.
  • None of the investigations should hinder the surgical management in emergency situations. In these circumstances, intraoperative examination under anaesthesia after stabilization of the fractures may be more appropriate.
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Staging

Staging in adults

Blake and McBryde used the terms true (or type I) injury and variant (or type II) injury to classify the floating-knee fracture pattern.[2, 4]

  • Type I is a pure diaphyseal fracture of the femur and tibia.
  • Type II is a fracture that extends into the knee, hip, or ankle joint. [4]

Fraser et al classified floating knee injuries in a similar way by analyzing knee involvement (see image below).[5]

Fraser classification of floating knee injuries. Fraser classification of floating knee injuries.

See the list below:

  • Type I is the same as the true injury Blake and McBryde described, [2] with extra-articular fractures of both bones.
  • Type II is subdivided into 3 groups, as follows:
    • Type IIa involves femoral shaft and tibial plateau fractures.
    • Type IIb includes fractures of the distal femur and the shaft of the tibia.
    • Type IIc indicates fractures of the distal femur and tibial plateau.

In both classification systems described above, type II fractures with intra-articular involvement have been linked with higher complication rates and poorer functional results than those observed with type I injuries.

The criteria Karlstrom and Olerud established are widely accepted for evaluating functional outcomes.[6, 7] The following data are recorded and characterized as excellent, good, acceptable, or poor (see image below):

Karlstrom and Olerud's criteria for assessing func Karlstrom and Olerud's criteria for assessing functional outcomes after a floating knee injury.

See the list below:

  • Subjective symptoms from the thigh or leg
  • Subjective symptoms from the knee or ankle joint
  • Walking ability
  • Participation in work and sports
  • Angulation and/or rotational deformity
  • Shortening
  • Restricted mobility of the hip, knee, or ankle joint

Staging in children

In children, floating knee injuries are classified according to the Bohn–Durbin or Letts classification systems.

In the Bohn–Durbin classification, floating knee injuries are described as follows:

  • Type I - Double-shaft pattern of fracture
  • Type II - Juxta-articular pattern
  • Type III - Epiphyseal

The Bohn–Durbin system does not account for open fractures and cannot be used to predict complications and prognoses.

Unacceptable findings are femoral union in a position of greater than 30° anterior angulation, 15° valgus angulation, and 5° posterior or varus angulation, or greater than 2 cm of shortening. Tibial malunion is defined as greater than 5° angulation in any plane or greater than 1 cm of shortening. Rotational malunion is defined as any internal rotational deformity exceeding findings on the unaffected side or greater than 20° external rotation of the extremity, as detected during walking or standing.

Letts et al designed a new classification system in which they recognized diaphyseal, metaphyseal, or epiphyseal knee fractures (types A, B, C) and also open fractures (types D and E) (see image below). The drawback of their classification system is that they do not indicate how to classify patients with epiphyseal separation in the distal femur and tibia or how to describe the location of open fractures in the epiphysis, metaphysis, or diaphysis.[8]

Letts and Vincent classification system for floati Letts and Vincent classification system for floating knee injuries in children.

Subjective outcomes of floating knee injuries can be evaluated by using the criteria Yue et al reported.[9] Their criteria are as follows:

  • Excellent - No complaints or limitations secondary to the injury to the extremity
  • Good - Occasional, minor pain in the extremity or a decreased ability to participate in athletic activities
  • Fair - Intermittent, moderate pain in the extremity but the patient is able to perform all activities of daily living and most recreational activities
  • Poor - Constant pain in the extremity and an inability to perform activities of daily living because of the injury to the extremity
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Contributor Information and Disclosures
Author

Srinivasa Vidyadhara, MBBS, MS, DNB MS(Ortho), DNB(Ortho), FNB(Spine Surgery), MNAMS, Consultant, Department of Spine Surgery, Manipal Hospital, India

Srinivasa Vidyadhara, MBBS, MS, DNB is a member of the following medical societies: AO Foundation, Scoliosis Research Society

Disclosure: Nothing to disclose.

Coauthor(s)

Mundkur Sudhakar Shetty, MBBS, MS, MCh Senior Professor and Head of Orthopedic Department, Yenapoya Medical College and Hospitals, Mangalore

Mundkur Sudhakar Shetty, MBBS, MS, MCh is a member of the following medical societies: American Academy of Orthopaedic Surgeons

Disclosure: Nothing to disclose.

Sharath K Rao, MBBS, MS, D'Ortho Professor and Head of Unit V, Department of Orthopedics, Kasturba Medical College Hospital, India

Sharath K Rao, MBBS, MS, D'Ortho is a member of the following medical societies: American Academy of Orthopaedic Surgeons, Indian Medical Association

Disclosure: Nothing to disclose.

James J Gnanadoss, MBBS MS(Ortho), Professor and Head of Unit, Director, Department of Orthopedics and Spine Surgery, Mahatma Gandhi Medical College Hospital, India

James J Gnanadoss, MBBS is a member of the following medical societies: AO Foundation

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

Carlos J Lavernia, MD FAAOS, Adjunct Clinical Professor, Department of Orthopedic Surgery, University of Miami School of Medicine; Medical Director, Orthopedic Institute at Mercy Hospital

Carlos J Lavernia, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, Biomedical Engineering Society, Orthopaedic Research Society, American Association of Hip and Knee Surgeons, Arthritis Foundation, Florida Orthopaedic Society

Disclosure: Received stock from Zimmer for implant designer.

Additional Contributors

Robert D Bronstein, MD Associate Professor, Department of Orthopedics, Division of Athletic Medicine, University of Rochester School of Medicine

Robert D Bronstein, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Society for Sports Medicine, Arthroscopy Association of North America, Medical Society of the State of New York

Disclosure: Nothing to disclose.

References
  1. Rethnam U, Yesupalan RS, Nair R. Impact of associated injuries in the floating knee: a retrospective study. BMC Musculoskelet Disord. 2009 Jan 14. 10:7. [Medline]. [Full Text].

  2. Blake R, McBryde Jr A. The floating knee: ipsilateral fractures of the tibia and femur. South Med J. 1975 Jan. 68(1):13-16. [Medline].

  3. Van Raay JJ, Raaymakers EL, Dupree HW. Knee ligament injuries combined with ipsilateral tibial and femoral diaphyseal fractures: the "floating knee". Arch Orthop Trauma Surg. 1991. 110(2):75-7. [Medline].

  4. Hung SH, Lu YM, Huang HT, Lin YK, Chang JK, Chen JC, et al. Surgical treatment of type II floating knee: comparisons of the results of type IIA and type IIB floating knee. Knee Surg Sports Traumatol Arthrosc. 2007 May. 15(5):578-86. [Medline]. [Full Text].

  5. Fraser RD, Hunter GA, Waddell JP. Ipsilateral fracture of the femur and tibia. J Bone Joint Surg Br. 1978 Nov. 60-B(4):510-5. [Medline].

  6. Karlström G, Olerud S. Ipsilateral fracture of the femur and tibia. J Bone Joint Surg Am. 1977 Mar. 59(2):240-3. [Medline].

  7. Rethnam U, Yesupalan RS, Nair R. The floating knee: epidemiology, prognostic indicators & outcome following surgical management. J Trauma Manag Outcomes. 2007 Nov 26. 1(1):2. [Medline].

  8. Letts M, Vincent N, Gouw G. The "floating knee" in children. J Bone Joint Surg Br. 1986 May. 68(3):442-6. [Medline]. [Full Text].

  9. Yue JJ, Churchill RS, Cooperman DR, et al. The floating knee in the pediatric patient. Nonoperative versus operative stabilization. Clin Orthop Relat Res. 2000 Jul. (376):124-36. [Medline].

  10. Chalidis B, Metha SS, Tsiridis E, Giannoudis PV. Mini-symposium: management of fractures around the knee joint. (ii) The "floating knee" in adults and children. Curr Orthop. 2006 Dec. 20(6):405-10. [Full Text].

  11. Dwyer AJ, Paul R, Mam MK, et al. Floating knee injuries: long-term results of four treatment methods. Int Orthop. 2005 Oct. 29(5):314-8. [Medline].

  12. Ostrum RF. Treatment of floating knee injuries through a single percutaneous approach. Clin Orthop Relat Res. 2000 Jun. (375):43-50. [Medline].

  13. Ríos JA, Ho-Fung V, Ramírez N, Hernández RA. Floating knee injuries treated with single-incision technique versus traditional antegrade femur fixation: a comparative study. Am J Orthop. 2004 Sep. 33(9):468-72. [Medline].

  14. Elmrini A, Elibrahimi A, Agoumi O, Boutayeb F, Mahfoud M, Elbardouni A, et al. Ipsilateral fractures of tibia and femur or floating knee. Int Orthop. 2006 Oct. 30(5):325-8. [Medline].

  15. Gao K, Gao W, Li F, Tao J, Huang J, Li H, et al. Treatment of ipsilateral concomitant fractures of proximal extra capsular and distal femur. Injury. 2011 Jul. 42(7):675-81. [Medline].

  16. Kao FC, Tu YK, Hsu KY, Su JY, Yen CY, Chou MC. Floating knee injuries: a high complication rate. Orthopedics. 2010 Jan. 33(1):14. [Medline].

  17. Hee HT, Wong HP, Low YP, Myers L. Predictors of outcome of floating knee injuries in adults: 89 patients followed for 2-12 years. Acta Orthop Scand. 2001 Aug. 72(4):385-94. [Medline].

  18. Yokoyama K, Nakamura T, Shindo M, et al. Contributing factors influencing the functional outcome of floating knee injuries. Am J Orthop. 2000 Sep. 29(9):721-9. [Medline].

  19. Kao FC, Tu YK, Hsu KY, Su JY, Yen CY, Chou MC. Floating knee injuries: a high complication rate. Orthopedics. 2010 Jan. 33(1):14. [Medline].

 
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Fraser classification of floating knee injuries.
Karlstrom and Olerud's criteria for assessing functional outcomes after a floating knee injury.
Letts and Vincent classification system for floating knee injuries in children.
Treatment protocol for floating knee injuries. Ex-Fix = external fixation; IM = intramedullary; ORIF = open reduction and internal fixation.
Floating knee injury.
Positioning for surgery to treat a floating knee injury.
Conservative management of the femur in an ipsilateral injury of this type is likely to result in malunion of the femoral fracture and shortening.
Early joint mobilization determines the patient's functional outcome after treatment of floating knee injuries. Nailing of both the tibial and the femoral fractures, as shown, is the best method for enabling early mobilization.
 
 
 
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