Revision surgery after failed unicompartmental knee arthroplasty

The Journal of Arthroplasty Vol. 15 No. 8 2000

Revision Surgery After Failed Unicompartmental Knee Arthroplasty A Study of 35 Cases Iris Bo¨hm, MD, and Franz Landsiedl, MD

Abstract: This retrospective study evaluates the results of 35 revision procedures after failed unicompartmental knee arthroplasty (UKA) in 34 patients, which were done during the period 1986 to 1996. There were 28 women and 6 men with a mean age of 71 years (range, 54 – 85 years). In all cases, St. Georg and Endo (W. Link, Hamburg, Germany) unicompartmental prostheses were used except 1 PCA unicondylar implant (Howmedica, Rutherford, NJ) and 1 Bo¨hler unicondylar implant (Allo Pro, Baar, Switzerland). Failures most frequently were due to aseptic loosening followed by polyethylene wear. Two deep infections occurred. Revisions were performed 1 week to 11 years after UKA; 23 were required within the first 5 years. In most cases, revision was to a total knee arthroplasty. Partial component exchange was done in 9 cases. All 34 patients were evaluated clinically after exchange arthroplasty. After a mean follow-up time of 4 years (range, 1–12.2 years), we found 11 excellent, 13 good, 4 fair, and 7 poor results according to the Hospital for Special Surgery score. The fair and poor results were due to aseptic loosening of the knee prosthesis in 6 knees. One of 2 patients with deep infection needed femoral amputation. With correct indication and considerable surgical experience, UKA is still a good alternative, especially in the elderly patient. Key words: revision surgery, failed unicompartment knee arthroplasty, total knee arthroplasty.

Unicompartmental knee arthroplasty (UKA) remains controversial. Compared with total knee arthroplasty (TKA), UKA provides a greater range of motion and preservation of bone stock and both cruciate ligaments [1,2]. Disadvantages are less durability and less predictable results [3,4]. Compared with high tibial osteotomy, UKA provides a higher success rate and fewer early complications [5]. The

purpose of this study was to evaluate the results of 35 revision procedures after failed UKA.

Material and Methods From 1982 to 1996, 299 UKAs were performed by various surgeons at the Orthopaedic Hospital Speising. Bilateral replacement was performed in 27 patients. Medial replacement was done in 292 knees, and lateral replacement was done in 7. All patients except for 20 who could not be reached for follow-up and 1 who died 2 weeks after UKA of a pulmonary embolus were evaluated clinically and radiographically with a mean follow-up time of 3.5 years (range, 1–12.9 years). From 1986 to 1996, 34 patients (28 women and 6 men) with a mean age of 71 years (range, 54 – 85

From the First General Orthopaedic Department, Orthopaedic Hospital Speising, Vienna, Austria. Submitted November 25, 1999; accepted May 26, 2000. No benefits or funds were received in support of this study. Reprint requests: Iris Bo¨hm, MD, Orthopaedisches Spital Speising, Speisingerstrasse 109, 1134 Wien, Austria. Copyright © 2000 by Churchill Livingstone威 0883-5403/00/1508-0006$10.00/0 doi:10.1054/arth.2000.9841

982

Revision Surgery After Failed UKA •

Bo¨hm and Landsiedl

983

Table 1. Revision Surgery After Failed Unicompartmental Knee Arthroplasty (n ⴝ 35) Failure Aseptic loosening (n ⫽ 17) Tibial plateau (n ⫽ 11)

Factors

Duration (y)

Ligament instability (n ⫽ 6) Varus (2) Valgus (1) Tibial subluxation (3)

Both implants (n ⫽ 5)

Femoral prosthesis (n ⫽ 1) Polyethylene wear (n ⫽ 6) Early wear (delamination) (n ⫽ 4)

Operative technique (n ⫽ 4) Plateau too small (1) Tilting femoral implant (2) Tilting tibial implant (1) Panarthrosis ⫹ polyethylene wear (n ⫽ 1) Ligament instability (n ⫽ 1) Varus (1) Operative technique (n ⫽ 2) Component malposition (1) Tilting femoral implant (1) Panarthrosis ⫹ polyethylene wear (n ⫽ 2) Valgus (1) Varus (1) PCA-UKA

Tilting femoral prosthesis (n ⫽ 2) Osteophyt ⫹ cement spur (n ⫽ 1) Increasing valgus (n ⫽ 1) Fracture medial tibial condyle (n ⫽ 1) Broken femoral prosthesis (n ⫽ 1)

5.1 3 1.3 0.3 0.6 3.5

No ACL, panarthrosis No ACL

5.5 2.5, 1.3 4 2

Femoral prosthesis impacted

4.2

Severe polyethylene wear

2.9 4.9

Lateral implants RA Overcorr. (valgus)

8 11 0.8

Overcorr. (valgus) (4)

3.1, 4.25 5.1, 6.5 8, 9.7 0.75, 1.1 3, 6, 6.5 3.1 7.2

Poor material (n ⫽ 4) Ligament instability (valgus) (1)

Normal wear (n ⫽ 2) Deep infection (n ⫽ 2) Panarthrosis (n ⫽ 4)

RA ⫹ no ACL (1) No ACL (1) Failed HTO, hyperext. def., overcorr. No ACL (1) No ACL, plateau too small, overcorr. (1) Tilting femoral implant, ACL intact (1)

Operative technique (n ⫽ 3) Incorrect indication (n ⫽ 1) Polyethylene wear ⫹ panarthrosis (n ⫽ 1) Polyethylene wear (n ⫽ 1) Operative technique (n ⫽ 1) Ligament instability (n ⫽ 1) Operative technique (n ⫽ 1)

Overcorr. (valgus) (3) Overcorr. (valgus) (1) Overcorr. (valgus) (1) Component malposition ⫹ impingement cement spur (1) Overcorr. (valgus) (1) Too much tibial bone resection

1.5 1.5 0.3 1 wk 9.5

RA: rheumatoid arthritis; ACL: anterior cruciate ligament; HTO, high tibial osteotomy; overcorr, overcorrection; hyper ext. def., hyperextension deformity; PE, polyethylene.

years) had 35 revision procedures after failed UKA. Three of these patients had implantation in other hospitals. Six patients had bilateral implants. There were 33 medial implants and 1 lateral implant. Indications were 23 knees with osteoarthrosis (22 varus deformities and 1 valgus deformity), 11 knees with osteonecrosis, and 1 knee with chondromatosis. Prior knee surgery had been performed on 6 patients. Four patients had had arthroscopic partial medial meniscectomy, and 1 patient had arthroscopic Pridie drilling of pridie-holes for femoral osteonecrosis [15]. One knee showed a hyperextension deformity of 16° after failed high tibial osteotomy. The implant types consisted of 26 Endo, 7 St.

Georg sledge (W. Link, Hamburg, Germany), 1 PCA unicondylar (Howmedica, Rutherford, NJ), and 1 Bo¨hler unicondylar (Allo Pro, Baar, Switzerland). All patients were reviewed clinically using the Hospital for Special Surgery scoring system and radiographically. The follow-up time was 1 to 12.2 years after revision surgery.

Results Most of the failures were caused by several factors (Table 1). Failures most frequently were due to aseptic loosening (17 patients—11 tibial implants, 1 femoral implant, 5 both implants); ligamentous in-

984 The Journal of Arthroplasty Vol. 15 No. 8 December 2000 Table 2. First and Second Revision Surgery After Failed Unicompartmental Knee Arthroplasty (n ⴝ 35) Failure

First Revision

Complication

Second Revision

Result

Aseptic loosening TKA-GSB (1) Tibial implant OOO™ TKA (5) (n ⫽ 11)

Exchange tibial implant (5) TKA (4) Both implants OOO™ TKA-GSB (1) (n ⫽ 5) Femoral implant OO™ Exchange femoral (n ⫽ 1) implant (1) Polyethylene wear OO™ TKA (4) (n ⫽ 6)

Exchange tibial implant (2) Deep infection OOOO 1-Stage exchange (n ⫽ 2) tibial implant (1) 2-Stage conversion TKA (1) Panarthrosis (n ⫽ 4) O TKA (1) UKA lateral (2) ASK Tilting femoral OOOO TKA implant (n ⫽ 2) Osteophyt ⫹ cement O™ ASK spur (n ⫽ 1) Increasing valgus OOO TKA (n ⫽ 1) Fracture tibial condyle O TKA (n ⫽ 1) Broken femoral OOO™ TKA implant (n ⫽ 1)

Good (1) Good (1) Excellent (2), Good (1)

Part. rupt. patellar tendon (1) Fracture tibial condyle (1) Superficial wound healing problem (1), fever (1) Antibiotic treatment (2) Broken femoral implant (1)

TKA (1)

Hematoma ⫹ superficial wound healing problem (1) Deep infection (1)

Femoral amputation

Deep infection (1)

2-Stage exchange arthroplasty Mobilization

Hematoma ⫹ limited flexion (1) Superficial wound healing problem ⫹ delayed mobilization (1) Deep vein thrombosis (1)

Excellent (2), good (1) Poor (after several fractures) (1)

Poor (loosening) (1)

(1) (2)

Exchange medial implants (1) TKA (1)

(1)

Component malalignment (1)

Exchange tibial implant (1)

(1)

Superficial infection, antibiotic treatment Superficial infection, antibiotic treatment Aseptic loosening tibial implant

(1)

Poor (loosening) (1)

Good (1), fair (pain) (1) Good (1)

Broken femoral implant medial (1) Incorrect indication Pulmonary embolus (1)

(1)

Excellent (3), good (2) Excellent (2), good (1), poor (limited ROM) (1) Poor (1)

Fair (1), poor (loosening) (1) Fair (pain) (1) Excellent (1), good (1) Good (1) Good (1) Good (1)

Exchange tibial implant

Fair (loosening) (1)

TKA, total knee arthroplasty; UKA, unicompartmental knee arthroplasty; ROM, range of motion; ASK, arthroscopy; GSB (Allo Pro, Baar, Switzerland); part. rupt., partial rupture.

sufficiency led to failures in 7 cases. Three cases showed anterior subluxation of the tibia, 2 of them with absent anterior cruciate ligament (ACL) and 1 with tilting of femoral implant. Three knees with aseptic loosening and ligament instability developed varus deformity again, 2 of them missing the ACL. One patient with hyperextension deformity after failed high tibial osteotomy would not be considered a candidate for a UKA today. One patient with varus deformity of 14° before UKA and absent ACL developed aseptic loosening and panarthrosis after 2 years. One medial and 1 lateral prosthesis showed loosening with panarthrosis after 8 and 11 years. Six cases with aseptic loosening were caused by poor operative technique. Radio-

graphic findings showed tilting of components (3 femoral implants, 1 tibial implant, 1 malalignment of both implants) in 5 cases. In the case with malalignment of both medial implants, severe polyethylene wear occurred and caused bone loss in the lateral femoral condyle. One tibial implant was too small and loosened. There was 1 case with femoral implant loosening of a PCA unicondylar (Howmedica). In cases requiring a second revision, polyethylene wear occurred in 6 cases, caused by poor polyethylene material showing severe delamination in 4 knees (Table 2). (Fig. 1) Two patients showed adequate polyethylene wear after 8 and almost 10 years’ time. Four knees developed panarthrosis, 3

Revision Surgery After Failed UKA •

of them from overcorrection (Fig. 3); the fourth patient would not meet the indication for UKA today because of his beginning panarthrosis. Further technical failures occurred in 4 patients. Tilting of the femoral prosthesis was found in 2 knees, 1 knee showed impingement of a cement spur, and 1 knee showed component malalignment. In 1 case, the medial tibial condyle fractured 1 week after UKA, caused by too much bone resection for the medial part of the tibial implant. Six knees with absent ACL and 1 patient with beginning panarthrosis and 1 patient having hyperextension deformity after failed high tibial osteotomy would not be candidates for UKA today. Two deep infections occurred and needed exchange arthroplasty; 1 sledge prosthesis broke after 9.5 years (Fig. 2). TKA was performed in 23 knees using 11 Natural (Sulzer), 8 Miller-Galante (Zimmer, Dietzenbach, Germany), 2 Total Condylar (Howmedica), and 2 GSB implants (Allo Pro). Partial component exchange was sufficient in 9 knees (8 tibial implants and 1 femoral implant). Two patients developed lateral osteoarthrosis by overcorrection and required lateral unicondylar replacement. In 2 knees, attempts were made to solve the problem with arthroscopy, but both patients needed further revision. During revision, additional synovectomy was done in 13 knees. Bone defects were filled with autogenous graft in 12 knees and with cement in 1 knee. This augmentation was not a significant issue during revision surgery. Six knees required lateral release, and 1 knee required shortening of the medial collateral ligament. Difficulties with patellar eversion occurred in 2 knees and resulted in 1 total and 1 partial rupture of the patellar tendon, which could be fixed with staples. One difficult exposure required a tibial tubercle osteotomy. The average time between primary operation and revision was 4 years (range, 1 week–11 years) (Fig. 4). The average follow-up evaluation was 4 years (range, 1–12.2 years). Using the Hospital for Special Surgery scoring system, there were 11 excellent, 13 good, 4 fair, and 7 poor results. The fair and poor results were caused mainly by aseptic component loosening in 6 knees. One patient with osteoporosis and several fractures of the hip and upper thigh could walk only a few steps with 2 crutches. One of 2 patients with deep infection required femoral amputation. Three patients complained about pain on walking. One of them had deep vein thrombosis in the postoperative period, and the other 2 showed limited range of motion.

Bo¨hm and Landsiedl

985

Fig. 1. Endo unicompartmental implant that has been removed shows severe polyethylene wear and delamination.

Complications Complications after revision surgery consisted of problems with superficial wound healing in 7 knees and 1 urinary tract infection, which all responded uneventfully to antibiotic treatment. Hematoma with limited motion in 1 knee was manipulated in the perioperative period. One pulmonary embolus and 1 deep vein thrombosis were treated successfully with medical management. More serious complications that led to a second revision included 2 deep infections and 1 aseptic loosening of tibial implant after TKA. Two femoral prostheses broke after partial component exchange. Deep infection was treated with delayed exchange arthroplasty in 1 case; the other case required femoral amputation because of sepsis. In 1 knee with a bicompartmental prosthesis, the medial femoral implant broke and needed revision (Fig. 3). Only the medial implants were changed. The other knee with broken femoral implant was changed to a TKA. The knee with aseptic loosening of the tibial implant after TKA was treated with a partial component exchange of the tibia (Fig. 2). The 2 patients with unsuccessful arthroscopy were revised a second time. One knee showed panarthrosis, and a TKA was done. The other knee showed malposition of components, and a partial component exchange of the tibial implant was done. This patient required a third revision because of anterior knee pain and limited range of motion. An arthroscopic lysis of adhesions and Pridie drilling of the patella was done [15].

Discussion Since its first use in the early 1970s, UKA has been controversial. Correct patient selection and

986 The Journal of Arthroplasty Vol. 15 No. 8 December 2000

Fig. 2. (A) Postoperative radiograph of a 69-year-old woman with a St. Georg unicompartment prosthesis. (B) Nine years later, the femoral implant is broken. (C) Radiograph after conversion to a Miller-Gallante total knee arthroplasty. (D) Nine months later, tibial implant shows aseptic loosening. (E) Four years after exchange arthroplasty of tibial implant with cement augmentation.

attention to technical details, avoiding overcorrection and component malposition, are required. Heinert and Engelbrecht [6] reported in a series of 2,236 St. Georg prostheses 10-year survival rates of 80% for medial UKAs, 77% for bicondylar implants, and 73% for lateral UKAs. Other authors reported 10-year survival rates of 70% to 85% [4,5,7–10]. Barrett and Scott [1] reported 19 excellent and good results in 29 revised UKAs after a mean follow-up time of 4.6 years. Padgett

et al [2] evaluated 19 revision procedures and reported excellent and good results in 16 patients. Lai and Rand [11] reported 81% excellent and good results after 48 exchange arthroplasties. Gill et al [12] compared a series of 30 revision procedures after UKA and high tibial osteotomy. After a follow-up of 3.8 years, they found better results in the group having high tibial osteotomy. Aseptic loosening is the most frequent reason

Revision Surgery After Failed UKA •

Bo¨hm and Landsiedl

987

Fig. 3. (A) Radiograph of a 79-year-old woman with an Endo unicompartmental implant. Postoperative alignment shows slight valgus overcorrection of 10° femorotibial angle. (B) Three years later, valgus malalignment has increased, and severe arthrosis of the unresurfaced compartment has developed. (C) Lateral Endo unicompartmental prosthesis has been implanted. (D) Three years later, medial sledge prosthesis is broken. (E) After exchange arthroplasty of medial implants. (F) Four years after revision, severe aseptic loosening is visible.

for failure, followed by progressive arthrosis of the unresurfaced compartment. Poor operative technique, such as overcorrection, can cause panarthrosis, and malposition of components can lead to aseptic loosening or polyethylene wear. Blunn et al [13] reported problems with polyethylene wear resulting from poor polyethylene material. Our results confirm these problems. Statistics on these few heterogeneous cases were not

worthwhile. Infection rate was 0.7%, and rate of revision procedures was 11.6%. Similar failure rates are published by other authors [6,10,14]. Failures occurred early (23 within the first 5 years) and resulted from overcorrection, ligamentous insufficiency, technical difficulties, or improper patient selection. In some cases, poor polyethylene material was responsible for early polyethylene wear. There was no significant correlation between duration of the unicondylar knee

988 The Journal of Arthroplasty Vol. 15 No. 8 December 2000

Fig. 4. Duration of retrieved unicompartmental knee arthroplasty (n ⫽ 35).

prosthesis and the polyethylene thickness (Fig. 5). Polyethylene implants ⬍7 mm thick were not used. Osseous defects were filled with autogenous bone– grafts and did not cause greater problems, in contrast to findings of other authors [2,12].

Conclusion Generally, UKA is a demanding procedure. In contrast to TKA, surgical technique, especially

Fig. 5. Duration of retrieved unicompartmental knee arthroplasty and polyethylene (PE) thickness (n ⫽ 35).

concerning the St. Georg and Endo prostheses, lacks good instrumentation and is mostly done freehand. Our results include the learning curve of several different surgeons. Revision surgery after failed UKA is more difficult than the primary operation, and the infection rate in this series was higher. Our experience suggests that with correct indications and considerable surgical experience, UKA is still a good means to treat unicompartmental arthrosis of the knee joint, especially in the elderly patient.

Revision Surgery After Failed UKA •

References 1. Barrett WP, Scott RD: Revision of failed unicondylar unicompartmental knee arthroplasty. J Bone Joint Surg Am 69:1328, 1987 2. Padgett DE, Stern SH, Insall JN: Revision total knee arthroplasty for failed unicompartmental replacement. J Bone Joint Surg Am 73:186, 1991 3. Ranawat CS, Flynn WF, Saddler S, et al: Long term results of the total condylar knee arthroplasty: a 15 year survivorship study. Clin Orthop 286:94, 1993 4. Swank M, Stulberg SD, Jiganti J, et al: The natural history of unicompartmental arthroplasty: an eightyear follow-up study with survivorship analysis. Clin Orthop 286:130, 1993 5. Weale AE, Newman JH: Unicompartmental arthroplasty and high tibial osteotomy for osteoarthrosis of the knee: a comparative study with a 12- to 17-year follow-up period. Clin Orthop 302:134, 1994 6. Heinert K, Engelbrecht E: Langzeitvergleich der Knie-Endoprothesensysteme St. Georg: 10-Jahres U¨berlebensraten von 2236 Schlitten- und ScharnierEndoprothesen. D Chirurg 59:755, 1988 7. Ansari S, Newman JH, Ackroyd CE: St. Georg sledge for medial compartment knee replacement: 461 arthroplasties followed for 4 (1–17) years. Acta Orthop Scand 68:430, 1997

Bo¨hm and Landsiedl

989

8. Christensen NO: Unicompartmental prosthesis for gonarthrosis: a nine-year series of 575 knees from a Swedish hospital. Clin Orthop 273:165, 1991 9. Marmor L: Unicompartmental arthroplasty for osteonecrosis of the knee joint. Clin Orthop 294:247, 1993 10. Scott RD, Cobb AG, McQueary FG, et al: Unicompartmental knee arthroplasty: eight- to 12-year follow-up evaluation with survivorship analysis. Clin Orthop 271:96, 1991 11. Lai CH, Rand JA: Revision of failed unicompartmental total knee arthroplasty. Clin Orthop 287:193, 1993 12. Gill T, Schemlitsch EH, Brick GW, et al: Revision total knee arthroplasty after failed unicompartmental knee arthroplasty or high tibial osteotomy. Clin Orthop 321:10, 1995 13. Blunn GW, Joshi AB, Minns RJ, et al: Wear in retrieved condylar knee arthroplasties. J Arthroplasty 12:281, 1997 14. Knutson K, Lindstrand A, Lidgren L: Survival of knee arthroplasties: a nation-wide multicentre investigation of 8000 cases. J Bone Joint Surg Br 68:795, 1986 15. Pridie KH: A method of resurfacing osteoarthritic knee joints. J Bone Joint Surg Br 41:618619, 1959