The Journal of Arthroplasty Vol. 24 No. 7 2009

Case Report

Fracture of the Medial Femoral Condyle AfterUnicompartmental Knee Arthroplasty

Kyung Tae Kim, MD, Song Lee, MD, Kun Ho Cho, MD, and Kwan Soo Kim, MD

Abstract: Periprosthetic fracture is a relatively rare but well-recognized complicationafter knee joint arthroplasty. We experienced a case of medial femoral condylarfracture among 700 cases of unicompartmental knee arthroplasty (UKA). The patientwas a 56-year-old woman who underwent minimally invasive UKA for medialosteoarthritis of the knee. A displaced medial femoral condylar fracture occurred 3years after UKA. A closed reduction and percutaneous fixation using 3 cannulatedcancellous screws was performed. Union of the fracture was achieved, and a fullrecovery of knee motion was gained after 3 months. The Knee Society knee andfunction scores were 87 and 80, respectively, at the 2-year follow-up. They were thesame as the scores before the fracture took place, and there was no evidence ofcomponent loosening or ligament instability. Keywords: unicompartmental kneearthroplasty, periprosthetic fracture, femoral condyle.© 2009 Elsevier Inc. All rights reserved.

Unicompartmental knee arthroplasty (UKA) hasbecome one of the popular methods in thetreatment of medial osteoarthritis of the kneerecently. Unicompartmental knee arthroplasty isnow performed through minimally invasive sur-gery, and it offers potential advantages including lesspostoperative pain, reduced blood loss, early reha-bilitation, quicker recovery of range of motion, andlower complications [1,2]. It is known that compli-cations of UKA are polyethylene wear, asepticloosening, dislocation of polyethylene bearing,contralateral osteoarthritis, periprosthetic fracture,limited motion, and unexplained severe pain [3,4].Among the complications, periprosthetic fracture is

From the Department of Orthopedic Surgery, Seoul Sacred HeartGeneral Hospital, Seoul, South Korea.

Submitted March 26, 2008; accepted September 5, 2008.No benefits or funds were received in support of the study.Reprint requests: Kyung Tae Kim, MD, Department of

Orthopedic Surgery, Seoul Sacred Heart General Hospital, 40-12Chungryangri-dong, Dongdaemoon-gu, Seoul, South Korea.

© 2009 Elsevier Inc. All rights reserved.0883-5403/08/2407-0027$36.00/0doi:10.1016/j.arth.2008.09.007

1143.e

a relatively rare but well-recognized complicationafter knee joint arthroplasty. Femoral supracondylarfractures after total knee arthroplasty (TKA) arerelatively common and have been widely reported[5,6]. Tibial condylar fractures after UKA also havebeen documented [4,7]. However, to our knowl-edge, there have been no reports about femoralcondylar fracture in patients undergoing UKA.

We performed more than 700 cases of UKA forpatients with osteoarthritis since January 2002, andduring the prospective follow-up, we experienced acase of medial femoral condylar fracture. This willtherefore be reported.

Case Report

The patient was a 56-year-old woman whounderwent minimally invasive UKA using theOxford partial knee phase 3 (Biomet Orthopedics,Inc, Warsaw, Ind) in April 2002 for medial osteoar-thritis of the left knee. At the time of UKA, thepreoperative Knee Society knee and function scoreswere 64 and 60 points, respectively, and range of

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ig. 2. (A and B), Clinical photographs show that theatient gained full recovery of knee motion at 3 monthsfter the operation.

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knee motion was 135°. At the 2-year regular follow-up after UKA, the Knee Society knee and functionscores were 87 and 80 points, respectively, and rangeof knee motion was 135°. A distal femoral fractureoccurred 3 years after UKA because of a slip and fallaccident in the bathroom. Radiographs show afracture of the medial femoral condyle (AO typeB2) with displacement (Fig. 1A). We performedclosed reduction and percutaneous fixation using6.5-mm cannulated cancellous screws under fluoro-scopic control (Fig. 1B). We gained union of thefracture and full recovery of knee motion after3 months (Fig. 1C, Fig. 2). The Knee Society kneeand function scores were 87 and 80 at the 2-yearfollow-up. They were the same as the scores before

ig. 1. (A), Preoperative radiographs of a 56-year-oldoman show a fracture of medial femoral condyle. (B),ostoperative radiographs after closed reduction andercutaneous screws fixation show satisfactory reductionf the fracture. (C), The follow-up radiographs aftermonths show solid union of the fracture.

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Fracture of the Medial Femoral Condyle After UKA � Kim et al 1143.e23

the fracture took place, and there was no evidence ofcomponent loosening or ligament instability.

Discussion

Unicompartmental knee arthroplasty is a treat-ment option for medial compartment osteoarthritisof the knee. Advantages of UKA are well known.They are less invasive, and there are less blood loss,lower morbidity and pain, conservation of normalstructures, knee kinematics and proprioceptions,rapid recovery, fewer early complications, andeasier revision surgery [1-3]. Complications ofUKA are relatively low, but there is unresolvedcontroversy about the cause of complications andtheir treatment. Among the complications, peripros-thetic fracture is a relatively rare but well-recog-nized complication after knee joint arthroplasty.Periprosthetic fractures after TKA usually occur atthe distal femur, and tibial fractures are relativelyrare. In contrast, periprosthetic fractures after UKAusually occur in the proximal tibia. Periprostheticfracture is a rare complication of UKA, but tibialcondylar fractures after UKA have been documen-ted [4,7]. Pandit et al [7] reported that the incidenceof tibial plateau fracture was less than 1% in morethan 1000 UKAs that have been implanted at theirinstitution and that fracture made up approximately1% of the cause for revision of UKA in the SwedishKnee Arthroplasty Register. Tibial plateau fracturesare a result of technical errors made during theprocedure, including unnecessarily deep verticalsaw cuts, excess removal of bone, or inadequatepreparation of the keel slot, and tend to be morecommon in smaller patients. If undisplaced, it can betreated conservatively. If diagnosed early, it isusually best reduced and fixed internally. If it causesproblems in the longer term, it is best treated byrevision to TKA [7].To our knowledge, there have been no reports

about femoral condylar fracture in patients under-going UKA, and so, there is no information aboutsupracondylar fractures after UKA. It is thereforenecessary to refer to periprosthetic fractures afterTKA and options for fracture management in theabsence of an implant. Isolated fractures of thefemoral condyle are uncommon. The mechanism ofinjury is thought to be an axial load with a varus orvalgus force. Muscle and ligamentous attachmentsoften lead to splaying, displacement, and rotationalmalalignment after fracture. Fractures of thefemoral condyle are occasionally associated withgross instability owing to disruption of the collateralor cruciate ligaments and the capsular structures of

the knee [8]. Operative treatment was recom-mended for all fractures of distal femur, with theexception of simple nondisplaced fractures. Dis-placed unicondylar fractures require surgical fixa-tion to prevent the complications of axialmalalignment, posttraumatic arthritis, knee stiff-ness, and instability. Some minimally displacedfractures can be treated with percutaneous reduc-tion and fixation, but open reduction is usuallynecessary to obtain an anatomic articular recon-struction. In patients with good bone stock, 6.5-mmcancellous lag screws provide secure fixation. Inpatients with osteoporotic bone, a T-buttress platemay be necessary to prevent migration of thecondyle [9]. Ostermann et al [10] reported overallexcellent long-term results of open reduction andinternal fixation for unicondylar fractures of thedistal femur, and they concluded that open reduc-tion and internal fixation of the fragment withcancellous screws was the method in the treatmentof displaced unicondylar fractures of the distalfemur. In our case, the fracture was a spiral anddisplaced unicondylar fracture. However, the com-ponents were intact and the alignment was accep-table. There was no ligament instability, and thebone stock was relatively good. It is known that thetreatment method that maintained the best qualityof the knee arthroplasty after fracture is openreduction and internal fixation [5]. However, forthe open reduction and internal fixation, we needextensive soft tissue dissection, and there is a risk ofinfection and damage to the component. It wastherefore treated with a closed reduction andfixation with percutaneous lag screws. It wasthought that this method might have some advan-tages, including less soft tissue damage, lower risk ofinfection and prosthetic component damage, andshorter operation time with operative intervention.After surgery, the reduction status was acceptableand the fracture site was relatively stable. Thecomponent fixation and limb alignment were good.

Conclusion

Periprosthetic fracture is a relatively rare but well-recognized complication after knee joint arthro-plasty. Periprosthetic fractures after TKA usuallyoccur at the distal femur, and periprosthetic frac-tures after UKA usually occur in the proximal tibia.Femoral condylar fracture is an unusual complica-tion after UKA. After a medial femoral condylarfracture after UKA, an acceptable outcome can begained using a closed reduction and percutaneousscrews fixation.

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