Partial knee replacement

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Contents

Overview

Unicompartmental knee arthroplasty is a surgical procedure used to relieve arthritis in one of the knee compartments in which the damaged parts of the knee are replaced. UKA surgery may reduce post-operative pain and have a shorter recovery period than a total knee replacements.[1] Also, UKA may have a smaller incision because the implants may be smaller.[2]

In the United States, this procedure constitutes approximately 8% of knee arthroplasty.[3]

Background

In the early 1950’s, Duncan C. McKeever figured that osteoarthritis could be isolated to only one compartment of the knee joint.[4] As a result, the entire knee did not need to be replaced if only one knee compartment was affected.[5] The UKA concept was designed to potentially have less trauma or damage than traditional total knee replacements by removing less bone and trying to maintain most of the patient’s bone and anatomy.[6] Also, the concept was designed to have smaller implants that would keep most of the patient’s bone, which may help patients return to normal function faster.[7]


Previously, UKA’s were not successful because the implants were poorly designed, proper patients were not selected, and the surgical technique was not optimal.[8] [9] [10] [11] [12] Recent advancements have been made to improve the design of the implants.[13] Also, picking the right patients was emphasized to make sure that the surgeons followed the indications and contraindications. Proper patient selection[14], following the indications/contraindications, and performing the surgery well are key factors for the success of UKA.[15]


Indications and Contraindications

UKA may be suitable for patients with moderate joint disease caused by painful osteoarthritis or traumatic injury, a history of unsuccessful surgical procedures or poor bone density that precludes other types of knee surgery.[16] Patients that may not be eligible for a UKA include patients that have an active or suspected infection in or about the knee joint, may have a known sensitivity to device materials, have bone infections or disease that result in an inability to support or fixate the new implant to the bone, have inflammatory arthritis, have major deformities that can affect the knee mechanical axis, have neuromuscular disorders that may compromise motor control and/or stability, have any mental neuromuscular disorder, patients who are not skeletally mature, are obese[17], have lost a severe amount of bone from the shin (tibia) or have severe tibial deformities, have recurring subluxation of the knee joint, have untreated damage to the knee cap and thigh bone joint (patellofemoral joint), have untreated damage to the opposite compartment or the same side of the knee not being replaced by a device, and/or have instability of the knee ligaments such that the postoperative stability the UKA would be compromised[18].


The anterior cruciate ligament (ACL) should be intact.[19] Although, this is debated by clinicians for patients that need a medial compartment replacement.[20] For patients that need a lateral compartment replacement, the ACL should be intact and is contraindicated for patients that have ACL-deficient knees because the lateral component has more motion than the medial compartment.[21]


History and physical examination

A physical examination and getting the patient’s history is performed before getting surgery.[22] A doctor may ask the patient to identify their pain with one finger.[23] If the patient has pain in one area of the knee, he or she may be a candidate for UKA.[24] But if the patient has pain in more than one area of the knee, he or she may not be a good candidate for UKA.[25] The doctor may take some radiographs (e.g., x-rays) to check for degeneration of the other knee compartments and evaluate the knee.[26] The physical exam may also include special tests designed to test the ligaments of the knee and other anatomical structures.[27] Most likely, the surgeon will decide to do a UKA during surgery where he/she can directly see the status of the other compartments.[28]


Surgical information

The surgeon may choose which type of incision and implant he or she should use for the patient’s knee. During the surgery, the surgeon may align the instruments to determine the amount of bone that should be removed.[29] The surgeon will remove bone from the shin bone (tibia) and thigh bone (femur).[30] The surgeon may decide to check if he or she removed the proper amount of bone during the surgery [31]. In order to make sure that the proper size implant is used, a surgeon may choose to use a temporary trial. After making sure the proper size implant is selected, the surgeon will put the implant on the ends of the bone and secure it with pegs. Finally, the surgeon will close the wound with sutures.[32]

Image:pkrvstotalknee.jpg


Benefits

The potential benefits of UKA include a smaller incision because the UKA implants are smaller than the total knee replacements, and the surgeon may make a smaller incision.[33] This may lead to a smaller scar.[34] Another potential benefit is less post-operative pain because less bone is removed. Also, a quicker operation and shorter recovery period may be a result of less bone being removed during the operation and the soft tissue may sustain less trauma.[35] Also, the rehabilitation process may be more progressive.[36] More specific benefits of UKA are it may improve range of motion, reduce blood loss during surgery, reduce the patient’s time spent in the hospital, and decrease costs.[37]


Risks

Blood clots (also known as deep vein thrombosis) are a common complication after surgery.[38][39] However, a doctor may prescribe certain medications to help prevent blood clots.[40][41] Infection may occur after surgery.[42] However, antibiotics may be prescribed by a doctor to help prevent infections.[43] Individual patient factors (i.e., anatomy, weight, prior medical history, prior joint surgeries) should be addressed with the patient’s doctor. There is some evidence that the rate of complications may be higher than with total knee arthroplasty.[44] The causes of long-term failure of UKA’s include polyethylene wear, loosening of the implant, and degeneration of the adjacent knee compartment.[45]


Long-term results

Long term studies reported excellent outcomes for UKA and the authors credit it to picking the proper patients[46], minimizing the amount of bone that is removed[47], and using the proper surgical technique[48]. One study found that at a minimum of 10 years follow up time after the initial surgery, the overall survival rate of the implant was 96%.[49] Also, 92% of the patients in this study had excellent or good outcome.[50] Another study, reported that at 15 years follow up time after the initial surgery, the overall rate of the implant was 93% and 91% of these patients reported good or excellent outcomes.[51]


External links

v • d • e
Orthopedic surgery, operations/surgeries and other procedures on the musculoskeletal system (ICD-9-CM V3 76-84)
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Muscle, tendon, fascia, and bursa
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References

  1. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18.
  2. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18.
  3. ^ Riddle DL, Jiranek WA, McGlynn FJ. Yearly incidence of unicompartmental knee arthroplasty in the United States. J Arthroplasty. 2008 Apr;23(3):408-12.
  4. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18
  5. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18
  6. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18
  7. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18
  8. ^ Insall J, Aglietti P. A five to seven-year follow-up of unicondylar arthroplasty. J Bone Joint Surg Am. 1980 Dec;62(8):1329-37.
  9. ^ Insall J, Walker P. Unicondylar knee replacement. Clin Orthop Relat Res. 1976 Oct(120):83-5.
  10. ^ Laskin RS. Unicompartmental tibiofemoral resurfacing arthroplasty. J Bone Joint Surg Am. 1978 Mar;60(2):182-5.
  11. ^ Swienckowski J, Page BJ, 2nd. Medial unicompartmental arthroplasty of the knee. Use of the L-cut and comparison with the tibial inset method. Clin Orthop Relat Res. 1989 Feb(239):161-7.
  12. ^ Swienckowski JJ, Pennington DW. Unicompartmental knee arthroplasty in patients sixty years of age or younger. J Bone Joint Surg Am. 2004 Sep;86-A Suppl 1(Pt 2):131-42
  13. ^ Swienckowski JJ, Pennington DW. Unicompartmental knee arthroplasty in patients sixty years of age or younger. J Bone Joint Surg Am. 2004 Sep;86-A Suppl 1(Pt 2):131-42
  14. ^ Geller JA, Yoon RS, Macaulay W. Unicompartmental knee arthroplasty: a controversial history and a rationale for contemporary resurgence. J Knee Surg. 2008 Jan;21(1):7-14.
  15. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18.
  16. ^ FDA. 510k Summary of Safety and Effectiveness: Triathlon Knee System Line Extension <http://www.fda.gov/cdrh/pdf7/K071881.pdf>. Accessed, 2007.
  17. ^ Bert JM. Unicompartmental knee replacement. Orthop Clin North Am. 2005 Oct;36(4):513-22.
  18. ^ FDA. 510k Summary of Safety and Effectiveness: Triathlon Knee System Line Extension <http://www.fda.gov/cdrh/pdf7/K071881.pdf>. Accessed, 2007.
  19. ^ Partial Knee Replacement <http://www.dhmc.org/ortho/knee/partialknee.html>. Accessed 2008 May 22. Dartmouth-Hitchcock Medical Center, Lebanon.
  20. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18.
  21. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18.
  22. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18
  23. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18
  24. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18
  25. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18
  26. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18
  27. ^ Geller JA, Yoon RS, Macaulay W. Unicompartmental knee arthroplasty: a controversial history and a rationale for contemporary resurgence. J Knee Surg. 2008 Jan;21(1):7-14.
  28. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18
  29. ^ Swienckowski JJ, Pennington DW. Unicompartmental knee arthroplasty in patients sixty years of age or younger. J Bone Joint Surg Am. 2004 Sep;86-A Suppl 1(Pt 2):131-42.
  30. ^ Swienckowski JJ, Pennington DW. Unicompartmental knee arthroplasty in patients sixty years of age or younger. J Bone Joint Surg Am. 2004 Sep;86-A Suppl 1(Pt 2):131-42.
  31. ^ Swienckowski JJ, Pennington DW. Unicompartmental knee arthroplasty in patients sixty years of age or younger. J Bone Joint Surg Am. 2004 Sep;86-A Suppl 1(Pt 2):131-42.
  32. ^ Swienckowski JJ, Pennington DW. Unicompartmental knee arthroplasty in patients sixty years of age or younger. J Bone Joint Surg Am. 2004 Sep;86-A Suppl 1(Pt 2):131-42.
  33. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18.
  34. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18.
  35. ^ Mullaji AB, Sharma A, Marawar S. Unicompartmental knee arthroplasty: functional recovery and radiographic results with a minimally invasive technique. J Arthroplasty. 2007 Jun;22(4 Suppl 1):7-11
  36. ^ Newman JH. Unicompartmental knee replacement. Knee. 2000 Apr 1;7(2):63-70.
  37. ^ Bert JM. Unicompartmental knee replacement. Orthop Clin North Am. 2005 Oct;36(4):513-22.
  38. ^ Colwell CW, Jr. Rationale for thromboprophylaxis in lower joint arthroplasty. Am J Orthop. 2007 Sep;36(9 Suppl):11-3.
  39. ^ Warwick D, Friedman RJ, Agnelli G, et al. Insufficient duration of venous thromboembolism prophylaxis after total hip or knee replacement when compared with the time course of thromboembolic events: findings from the Global Orthopaedic Registry. J Bone Joint Surg Br. 2007 Jun;89(6):799-807.
  40. ^ Colwell CW, Jr. Rationale for thromboprophylaxis in lower joint arthroplasty. Am J Orthop. 2007 Sep;36(9 Suppl):11-3.
  41. ^ Warwick D, Friedman RJ, Agnelli G, et al. Insufficient duration of venous thromboembolism prophylaxis after total hip or knee replacement when compared with the time course of thromboembolic events: findings from the Global Orthopaedic Registry. J Bone Joint Surg Br. 2007 Jun;89(6):799-807.
  42. ^ Ritter MA, Olberding EM, Malinzak RA. Ultraviolet lighting during orthopaedic surgery and the rate of infection. J Bone Joint Surg Am. 2007 Sep;89(9):1935-40.
  43. ^ Warwick D, Friedman RJ, Agnelli G, et al. Insufficient duration of venous thromboembolism prophylaxis after total hip or knee replacement when compared with the time course of thromboembolic events: findings from the Global Orthopaedic Registry. J Bone Joint Surg Br. 2007 Jun;89(6):799-807.
  44. ^ Amin AK, Patton JT, Cook RE, Gaston M, Brenkel IJ. Unicompartmental or total knee arthroplasty?: Results from a matched study. Clin Orthop Relat Res. 2006 Oct;451:101-6.
  45. ^ Borus T, Thornhill T. Unicompartmental knee arthroplasty. J Am Acad Orthop Surg. 2008 Jan;16(1):9-18.
  46. ^ Berger RA, Meneghini RM, Jacobs JJ, et al. Results of unicompartmental knee arthroplasty at a minimum of ten years of follow-up. J Bone Joint Surg Am. 2005 May;87(5):999-1006
  47. ^ Price AJ, Waite JC, Svard U. Long-term clinical results of the medial Oxford unicompartmental knee arthroplasty. Clin Orthop Relat Res. 2005 Jun(435):171-80
  48. ^ Berger RA, Meneghini RM, Jacobs JJ, et al. Results of unicompartmental knee arthroplasty at a minimum of ten years of follow-up. J Bone Joint Surg Am. 2005 May;87(5):999-1006
  49. ^ Berger RA, Meneghini RM, Jacobs JJ, et al. Results of unicompartmental knee arthroplasty at a minimum of ten years of follow-up. J Bone Joint Surg Am. 2005 May;87(5):999-1006
  50. ^ Berger RA, Meneghini RM, Jacobs JJ, et al. Results of unicompartmental knee arthroplasty at a minimum of ten years of follow-up. J Bone Joint Surg Am. 2005 May;87(5):999-1006
  51. ^ Price AJ, Waite JC, Svard U. Long-term clinical results of the medial Oxford unicompartmental knee arthroplasty. Clin Orthop Relat Res. 2005 Jun(435):171-80

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