Journal of Orthopaedic Surgery 2013;21(3):281-4
Bicompartmental versus total knee arthroplasty for medial and patellofemoral osteoarthritis Shi Ming Tan, Andrew Q Dutton, Kia Chuang Bea, V Prem Kumar
Department of Orthopaedic Surgery, National University Hospital, Singapore
ABSTRACT Purpose. To compare the outcome of bicompartmental knee arthroplasty (BKA) versus total knee arthroplasty (TKA) in patients with medial and patellofemoral knee osteoarthritis. Methods. Records of 17 women and 10 men with medial and patellofemoral osteoarthritis of the knee who underwent BKA (n=15) or TKA (n=12) were reviewed. All surgeries were performed by the same surgeon. Patient haemoglobin level, length of hospital stay, range of motion, and visual analogue score for pain were recorded, as were the Knee Society Score, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the SF-36 score. Results. Patients treated with BKA were younger than those treated with TKA (mean age, 52 vs. 60 years; p=0.006). BKA resulted in longer mean operating time (99 vs. 85 minutes, p=0.025), less mean intra-operative blood loss (reduction in haemoglobin level) [1.2 vs. 2.4 g/dL, p=0.003), and greater mean postoperative range of movement (125º vs. 116º, p=0.019). The mean
Knee Society scores, WOMAC, and SF-36 scores in both groups were not significantly different. There was no instance of implant loosening, peri-prosthetic fractures, patellar subluxation, and dislocation. Conclusion. Short-term outcome of BKA and TKA was comparable. Key words: arthroplasty, replacement, osteoarthritis, knee; patellofemoral joint
knee;
INTRODUCTION Osteoarthritis of the knee may involve the medial, lateral, and patellofemoral compartments. The incidence of knee osteoarthritis in the United States population aged >60 years was 37.4%.1 In a large proportion of such patients, the medial and patellofemoral compartments are involved but the lateral compartment is spared.2 Conventionally, such patients are treated with total knee arthroplasty (TKA). Various surgical options provide an alternative to TKA for this subset of patients.2,3 Bicompartmental knee arthoplasty (BKA) has been advocated, as it is
Address correspondence and reprint requests to: Dr Shi Ming Tan, Department of Orthopaedic Surgery, National University Hospital, Singapore, 5 Lower Kent Ridge Road, Singapore 119074. Email:
[email protected] Journal of Orthopaedic Surgery
282 SM Tan et al.
less invasive and more tissue-sparing. Its benefits include a smaller incision with less tissue trauma, less bone removal, reduced tension on patella, absence of translation of the tibia, and absence of dissection of the lateral geniculate vessels.2,4 In addition, BKA preserves the cruciate ligaments, restores knee alignment, and enables an improved gait pattern.5,6 Two BKA designs have been used. One is a monolithic device, which has poor outcome.7,8 The other is a unicompartmental knee arthroplasty in conjunction with a patellofemoral device, which has yielded promising outcome.9 This study compared the outcome of BKA (unicompartmental knee arthroplasty in conjunction with a patellofemoral device) versus TKA in patients with medial and patellofemoral knee osteoarthritis.
(a)
MATERIALS AND METHODS Records of 17 women and 10 men with grades 2 to 4 (minimal to severe) medial and patellofemoral osteoarthritis of the knee (according to the KellgrenLawrence scale10) and an intact anterior cruciate ligament who underwent BKA (unicompartmental knee arthroplasty in conjunction with a patellofemoral device, n=15) or TKA (n=12) between March 2008 and December 2010 were reviewed. Patients with unicompartmental or tricompartmental osteoarthritis or inflammatory arthritis were excluded. The prosthesis for BKA was the Zimmer Unicompartmental High Flex Knee prosthesis in conjunction with the Zimmer Gender Solutions Patellofemoral Joint System (Fig.), whereas the prosthesis for TKA was the NexGen LPS-Flex Mobile Knee System. In both groups, the patella was resurfaced with the NexGen Polyethylene Patellar Button. All surgeries were performed by the same surgeon. For BKA, the medial parapatellar approach was used via a median incision. The patella was subluxed and trochlear bone cuts were performed with jigs, followed by checking of patellar tracking. No lateral release was required in these patients. A limited medial release was performed and the medial meniscus was excised. A tibial cut was made and a spacer block inserted to ensure full extension and flexion. The alignment was undercorrected and kept minimally varus. Femoral cuts were then performed with jigs, and trial implants were inserted. Upon confirmation of joint stability and good range of movements, definitive implants were cemented, and the patella was resurfaced. Patient characteristics, body mass index,
(b)
Figure Radiographs of the knee (a) before and (b) after bicompartmental knee arthroplasty in conjunction with a patellofemoral device.
Vol. 21 No. 3, December 2013
Bicompartmental versus total knee arthroplasty for medial and patellofemoral osteoarthritis 283 Table Patient characteristics and outcome
Parameter
Bicompartmental knee arthroplasty (n=15)
Total knee arthroplasty (n=12)
p Value
52 (41–62) 24.3 (17–33) 67 26.0±4.2 99 (63–112) 1.2±0.7
60 (41–63) 20.0 (16–28) 58 28.3±4.9 85 (65–98) 2.4±0.91
0.006 0.114 0.706 0.152 0.025 0.003
11.9±1.3 5.3±1.5
11.1±1.1 6.3±1.3
0.126 0.093
109±21 125±12 9±17
113±13 116±10 4±10
0.323 0.019 0.486
7.4±2.5 3.5±1.9
6.5±2.4 2.8±1.7
0.399 0.456
36.5±10.3 90.0±9.5 86.3±11.5 87.5±9.1
38.1±12.6 84.1±12.8 90.0±10.7 90.2±7.4
0.087 0.427 0.323 0.651
49.7±14.2 76.0±11.8 80.7±12.2 79.2±9.0
57.5±7.5 78.8±13.8 79.2±10.8 84.4±8.8
0.083 0.516 0.648 0.193
63.7±6.8 86.6±6.6 88.8±9.5 91.6±3.6
67.9±11.2 80.1±11.7 85.5±7.0 87.9±7.0
0.341 0.167 0.148 0.169
47.5±6.6 48.9±7.4 50.4±4.7
48.6±6.7 51.3±3.9 51.9±3.7
0.683 0.399 0.464
57.0±2.8 54.8±6.8 55.5±6.8
54.9±5.3 54.5±4.6 55.4±3.6
0.399 0.323 0.508
Mean (range) patient age (years) Mean (range) follow-up period (months) % of females Mean±SD body mass index (kg/m2) Mean (range) operating time (minutes) Mean±SD intra-operative blood loss (reduction in haemoglobin level) [g/dL] Mean±SD postoperative haemoglobin level (g/dL) Mean±SD length of hospital stay (days) Mean±SD range of movement (degrees) Preop Postop Improvement Mean±SD pain score (visual analogue scale) Preop 6 months Mean±SD Knee Society Knee Score 0 month 6 month 12 month 24 month Mean±SD Knee Society Function Score 0 month 6 month 12 month 24 month Mean±SD Western Ontario and McMaster Universities Osteoarthritis Index 0 month 6 month 12 month 24 month Mean±SD SF-36 physical component summary score 6 month 12 month 24 month Mean±SD SF-36 mental component summary score 6 month 12 month 24 month
haemoglobin level, comorbidities, length of hospital stay, range of motion, and visual analogue score for pain were recorded, as were the Knee Society Score,11 the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the SF-36 score. The 2 groups were compared using the MannWhitney U test. A p value of