http://upload.orthobullets.com/topic/5023/images/patellar_maltracking.jpg
http://upload.orthobullets.com/topic/5023/images/pcl_rupture.jpg
http://upload.orthobullets.com/topic/5023/images/patella_baja.jpg
http://upload.orthobullets.com/topic/5023/images/extensor_mechanism_rupture.jpg
http://upload.orthobullets.com/topic/5023/images/ho.jpg
Introduction
  • TKA Complications discussed in this topic
    • vascular injury
    • wound complications
    • metal hypersensitivity
    • heterotopic ossification
    • blood loss and anemia
  • TKA Complications in other topics
    • periprosthetic infection 
    • periprosthetic fracture 
    • patellar clunk  
    • patellar maltracking
    • instability (tibio-femoral)
    • stiffness
    • extensor mechanism rupture
    • neurologic injury (peroneal nerve)
Patellar Component Loosening
  • Introduction 
    • epidemiology
      • 0.6-5% of cases
        • more common with metal-backed patellae
    • etiology
      • subclinical infection
      • maltracking or overstuffing, leading to high shear
    • risks
      • obesity
      • lateral release
      • joint-line elevation
      • postoperative flexion >100°
      • poor bone stock
      • asymmetric patellar resection
      • inadequate implant fixation (small pegs)
      • secondary osteonecrosis and osteolysis
  • Imaging
    • radiographs
      • lateral view
        • show patellar component adjacent/superficial to patella
        • show loss of radiolucent space in patellofemoral joint and contact between patella bone and femoral component
  • Treatment
    • revision of patellar component
      • if revision fails, resection of patellar component
Vascular Injury
  • Introduction
    • incidence
      • .017%-.2%
    • risk factors 
      • sharp dissection in posterior compartment of knee
      • posterior retractor placement
        • stay medial with single-prong retractor (do not go lateral to PCL)   
          • popliteal artery is a lateral structure at the level of the joint line
        • do not insert retractor more >1cm into posterior soft tissues
      • pre-existing vascular disease
    • causes
      • direct laceration
      • thrombosis
  • Anatomy
    • lateral structure as it crosses knee
    • 1 cm behind tibial plateau in extension
    • 2 cm behind tibial plateau in flexion
  • Treatment
    • immediate vascular surgery consultation
Wound Complications
  • Introduction
    • risk factors 
      • systemic factors
        • DM II
        • vascular disease
        • rheumatoid arthritis
        • certain medications
        • tobacco
        • poor nutritional status
        • albumin <3.5g/dL
        • total lymphocyte count <1,500/uL
        • perioperative anemia
        • obesity
      • local factors
        • previous incisions
          • skin bridges should be >5-6cm
          • avoid crossing previous skin incisions at an angle <60 degrees
        • knee deformity
        • skin adhesions
        • poor local blood supply
      • technique
        • large subcutaneous skin flaps
        • not preserving subcutaneous fat layer
      • postoperative
        • hematoma
        • infection
  • Evaluation
    • must rule-out infection
  • Treatment
    • debridement and coverage with rotational flap 
      • indications
        • full-thickness necrosis
Metal Hypersensitivity
  • Introduction
    • incidence
      • rare
    • cause
      • nickel found in cobalt-chromium alloys
  • Evaluation
    • patch testing
    • lymphocyte transformation test (LST)
  • Treatment
    • revise to nonallergenic metal prosthesis
Heterotopic Ossification
  • Introduction
    • incidence
      • less frequent than after THA 
    • risk factors 
      • periosteal stripping off anterior femur
      • male gender
      • obesity
      • post traumatic deformity
Blood Loss & Anemia
  • Risk factors
    • closed suction drainage
      • associated with increased incidence of transfusion 
 

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Questions (4)

(OBQ11.126) A patient undergoes the procedure depicted in Figures A and B with standard components (non-gender specific). Which of the following outcomes most appropriately describes the difference in females compared to males for this procedure? Review Topic

QID:3549
FIGURES:
1

Greater implant survivorship

72%

(1297/1802)

2

Decreased WOMAC scores

13%

(236/1802)

3

Increased rate of extensor mechanism rupture

3%

(52/1802)

4

Increased postoperative pain

10%

(177/1802)

5

Increased component osteoloysis

2%

(32/1802)

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

Females undergoing total knee arthroplasty with standard (non-gender specific) components show improved implant survivorship compared to males.

MacDonald et al performed a Level 2 study of 3817 patients who underwent 5279 primary total knee replacements (3100 female, 2179 male) with a minimum of 2 years followup. They found that women demonstrated greater implant survivorship, greater improvement in WOMAC scores, equal improvements in SF-12 scores, and less improvement in only the Knee Society function and total scores.

Greene discusses the role of gender-specific implant designs that are currently marketed and their benefit to patients. The article concludes that the amount of attention that implant manufacturers have focused on female specific components(e.g. narrower M/L dimensions, decreased thickness of the anterior flange, and increased trochlear groove angle) is of interest, considering that there is no evidence suggesting that females have inferior outcomes with standard components.


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(OBQ10.270) A 55-year-old patient is scheduled for total knee arthroplasty. A radiograph is provided in Figure A. Each of the following are risk factors for heterotopic ossification EXCEPT? Review Topic

QID:3253
FIGURES:
1

Incorrect sizing of femoral and/or tibial components

62%

(758/1217)

2

Male gender

8%

(99/1217)

3

Obesity

17%

(209/1217)

4

History of trauma

2%

(23/1217)

5

Presence of preoperative osteophytes (hypertrophic arthrosis)

10%

(125/1217)

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

Heterotopic bone ossification (HO) following TKA has not been associated with valgus knee deformity. HO formation can be problematic both after a THA and TKA, but unlike the hip, it rarely becomes a clinical problem. The overall incidence of HO after TKA varies greatly among published studies, ranging from 15-50%. In the study by Dalury et al, they noted a 15% HO incidence. Among those with HO, 95% had osteoarthritis and 5% had a history of inflammatory arthritis. In their study, obese and male patients also had a higher incidence of developing post-operative HO. Toyoda et al in their study showed a significantly higher rate of HO in patients with osteoarthritis and pre-operative osteophyte formation (hypertrophic arthrosis). Overall, the signficant risk factors include hypertrophic arthrosis (often seen with trauma), male gender, and obesity.


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Question COMMENTS (4)

(OBQ05.142) A 65-year old healthy male has just undergone primary total knee arthroplasty. Which of the following is associated with use of a closed suction drain in this procedure? Review Topic

QID:1028
1

Increased incidence of wound dehiscence

1%

(8/1566)

2

Increased incidence of transfusion

74%

(1162/1566)

3

Decreased incidence of infection

1%

(13/1566)

4

Decreased incidence of hematoma formation requiring return to OR

21%

(336/1566)

5

Decreased pain scores on post-op days 1 and 2

3%

(47/1566)

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

The cited meta-analysis by Parker et al evaluated 18 studies with 3495 patients (3689 wounds) and demonstrated that closed suction drainage increases the transfusion requirements after elective hip and knee arthroplasty (relative risk, 1.43; 95% confidence interval, 1.19 to 1.72). They found no significant effect on wound hematoma, infection, or operations for wound complications.


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(OBQ04.103) A 62-year-old female underwent a primary total knee arthroplasty of the left knee 10 days ago. She presents to clinic with skin necrosis of the midline incision. There is no deep infection present upon aspiration of the knee joint. She undergoes superficial irrigation and debridement and is left with exposed patellar tendon as shown in Figure A. What is the most appropriate next step in management? Review Topic

QID:1208
FIGURES:
1

Split thickness skin grafting

7%

(35/537)

2

Twice daily wet-to-dry dressing changes with Dakin's solution until healing by secondary intention

2%

(10/537)

3

Latissimus dorsi free flap transfer

2%

(10/537)

4

Vacuum-assisted closure device until healing by secondary intention

9%

(49/537)

5

Medial gastrocnemius muscle flap transfer and skin grafting

80%

(431/537)

Select Answer to see Preferred Response

PREFERRED RESPONSE 5

Medial gastrocnemius muscle flap transfer and skin grafting is the most appropriate choice of the options listed (postoperative image shown in Illustration A).

Level 4 evidence by Ries describes 9 patients sustained skin necrosis after total knee arthroplasty. Seven of these cases were over the patella tendon or tibial tubercle, of whom 6 were treated with medial gastrocnemius flap coverage. Successful wound healing and salvage of the TKA was achieved in all cases. Ries concluded that necrosis of the proximal wound including the area over the patella can be treated by local wound care and skin grafting. However, skin necrosis over the tibial tubercle or patellar tendon requires muscle flap coverage to prevent extensor mechanism disruption and deep infection.

ILLUSTRATIONS:

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