HIGH TIBIAL OSTEOTOMY: TREATMENT FOR UNICOMPARTMENTAL ARTHRITIS

JOHN A. EVANS, MD, and CHRISTINE L. MADRID, RN, MSN, CRNFA, ONC

Unicompartmental arthritis in the active patient represents a treatment challenge for the orthopedic surgeon. Nonoperative modalities should be tried, but are met with little success. Arthroscopic debridement alone is also helpful initially, but does not address the problem of overload in the involved compartment. Osteotomy provides for reduction of forces by permanent realignment of the mechanical axis of the extremity. This study consists of 24 patients and 26 knees that underwent high tibial osteotomy for medial compartment arthritis. Single-stance weight-bearing radiographs were used for evaluation. All osteotomies were stabilized using the 3M Bone Stapilizer. There were no nonunions and the average time to union was 7.7 weeks. The average correction was 6.7 ° of valgus angulation. Patients were studied for a period of 36 to 84 months. This technique allows for accurate and reproducible high tibial osteotomies. The rigid fixation provided by the use of the stapilizer allowed immediate range of motion and early partial weight-bearing activity without loss of correction. KEY WORDS: arthritis, medial compartment arthritis, osteotomy, uncompartmental arthritis

Operative arthroscopy has reduced the incidence of postmenisectomy arthritis, but orthopedic surgeons are still faced with a large pool of middle-aged athletes who required open medial menisectomy and have now devel- oped posttraumatic arthritis. This does not exclude the lateral compartment, but the greater incidence of medial menisectomy, combined with the medial side bearing 60% of the normal forces transmitted through the knee joint, produces this condition. 1 Patients who present with medial compartment arthritis, who have had an ath- letic injury to the knee but no surgery, may have suffered a "bone bruise" that might have been diagnosed by mag- netic resonance imaging (MRI) had this study been avail- able.

Nonoperative treatment of medial compartment arthri- tis should include nonsteroidal anti-inflammatory medi- cations, restriction of those activities that significantly in- crease the load through the medial compartment, weight control, and the use of wedged insoles and braces. 2 Unfortunately, these measures usually fail and surgery becomes necessary. Many patients procrastinate about their condition, and this combined with surgeons who are reticent to recommend aggressive treatment of medial compartment arthritis in the middle-aged group, results in the patient missing the golden opportunity to benefit from osteotomy. Although arthroscopic joint debride- ment has become common and this procedure is helpful in addressing mechanical intra-articular problems, it does not alter the weight-bearing forces through the knee joint and, in fact, may increase the force after menisectomy. 3

Studies have been performed attempting to measure

From the Orthopaedic Surgical Associates of San Antonio, TX. Address reprint requests to John A. Evans, MD, 414 Navarro St,

#1128, San Antonio, TX 78205. Copyright © 1995 by W. B. Saunders Company 1060-1872/95/0302-0006505.00/0

functional loading, but this is a difficult technique. 4"s However, the concept of functional unloading of the malaligned knee is the basis for osteotomy. Medial com- partment arthritis with a varus deformity can be treated by valgus osteotomy reversing excessive loads in the me- dial compartment and transferring some of this load to the normal lateral compartment. The reverse is true with lateral compartment arthritis and a valgus deformity when performing a varus osteotomy. Transferring load from an affected compartment to an unaffected compart- ment should result in pain relief and improved func- tion. 1,6

Patients with unicompartmental arthritis must be eval- uated clinically, mechanically, and radiographically to de- termine if they are candidates for osteotomy.

CLINICAL ASSESSMENT

The patient should have an essentially normal range of motion, but a flexion contracture of up to 10 ° is accept- able. These patients should have an obvious deformity, and this should be clinically correctable. The pain should be localized to the medial compartment and if this is not the case, other possibilities of internal derangement producing pain must be eliminated by diagnostic arthros- copy. The patient's age, weight, and activity level must also be taken into consideration. This type of operation should be limited to those patients who are less than 65 years old, who are not overweight, and are in good health.

MECHANICAL ASSESSMENT

The knee must have no gross ligamentous instability. Osteotomy will not improve instability and, in fact, can make this clinical condition worse. 7 Isolated anterior cruciate instability may be an exception.

112 Operative Techniques in Sports Medicine, Vol 3, No 2 (April), 1995: pp 112-116

RADIOLOGICAL ASSESSMENT The patient's pain must correlate with the radiographs and be localized to the involved compartment. This is best performed by multiple views including anterior- posterior (AP), lateral, tunnel, and patellar views. The mechanical axis of the limb is measured by a single-stance 3-ft film that includes the femoral head and the ankle joint (Fig 1). The arthritis seen on plain films should be predominant ly unicompartmental . There are short- term studies in the literature indicating that patients with varus deformity and some lateral compartment involve- ment do well with valgus osteotomy. 8 This is more likely in the younger patient.

Any discrepancy in the location of the patient's pain must be clarified either by MRI or arthroscopy. Patients with patellofemoral arthritis radiographically can also be improved with osteotomy by slight anterior displacement of the osteotomy site. This decompresses the patello- femoral joint and may provide symptomatic relief. 9 Early to moderate changes in the patellofemoral compart- ment do not rule out osteotomy.

PREOPERATIVE EVALUATION Once it has been decided that the patient is a candidate for high tibial osteotomy, preoperative evaluation should include templating of the radiographs to determine the

degree of osteotomy desired (Fig 2). The osteotomy should be performed not only to restore the tibiofemoral angle of 5 ° to 7 ° (0 ° of mechanical axis) but that overcor- rection to at least 10 ° of anatomical valgus or greater than 5 ° of mechanical valgus produces the best resultsJ °

Originally, high tibial osteotomy was performed distal to the tibial tubercle, but the complication rate was high, including nonunion and significant loss of correction. To avoid these complications Coventry 11 and others have advocated that the osteotomy be performed above the tibial tubercle. This produces a more rapid union and stable correction because of the large surface area of me- taphyseal bone. Numerous methods of fixation have been used including staples, external fixators, and vari- ous types of plates and screws. 1'1~ All patients in this series presented with classical medial compartment ar- thritis, and all osteotomies were performed above the tib- ial tubercle. The templating is essential to the operative technique, and should be available in the operating room for inspection and review. If patients have not under- gone recent preoperative arthroscopic examination, it is imperative that, at the time of osteotomy, arthroscopy be performed and that any abnormal intra-articular condi- tion be treated. If the patient has significant lateral com- partment involvement, the procedure may be termi- nated. However, if they have only minimal lateral com- partment involvement for their age, and the disease process seems to be mainly medial and unicompartmen-

Fig 1, The mechanical axis of the lower extremity is mea- sured from the center of the femoral to the center of the ankle joint.

Fig 2. Templating preoperative radiographs determines the size of the lateral wedge.

TREATMENT FOR UN!COMPARTMENTAL ARTHRITIS 113

tal, then the patient is further prepared for osteotomy with appropriate reprepping and draping as indicated.

SURGICAL TECHNIQUE

The operation is performed with the knee in 90 ° of flexion and a modified kidney rest is used to support the leg during the procedure. A proximal horizontal incision is made extending from the tibial tubercle and proceeding laterally over the fibular head. Subcutaneous tissues are dissected and this is carried over to the fibular head. At this point, sufficient dissection is performed to expose the peroneal nerve. Initially, it is identified by palpation and is then brought into view with careful dissection. It is protected during the procedure with a 1/4-in Penrose drain. Once the peroneal nerve has been protected, the proximal attachment of the anterior tibial compartment musculature to the fibial flare is sharply dissected and reflected anteriorly. This dissection is carried down to the tibial tubercle and then laterally to expose the anterior and the medial portion of the fibular head. Small bun- ion retractors are placed around the neck of the fibula and again the position of the peroneal nerve is noted to be sure it is protected. In most cases, a complete fibular head osteotomy is not necessary, but removal of the an- teromedial portion of the fibular head only provides enough decompression of the proximal tibiofibular joint. This permits the leg to be brought into the correct degree of valgus after osteotomy and wedge removal. This method prevents any significant disruption of the fibular collateral ligament or the biceps tendon attachment and reduces pain caused by the absence of an unstable oste- otomy of the fibular neck. Once this portion of the fib- ular head has been excised, good access is available to the lateral and posterolateral compartment and the anterior aspect of the tibia.

The deep infrapatellar bursa is identified and it is through this bursal area that the osteotomy will traverse the horizontal plane anteriorly. Under image intensifier control, a 3/16-in Steinman pin is placed from lateral to medial just beneath the subchondral bone of the lateral and medial tibial plateaus. The pin should be placed in the midportion of the proximal tibia anterior to posterior. It may be helpful to localize the joint line with an 18 gauge spinal needle when inserting the Steinman pin.

The osteotomy site, as preoperatively planned, has been transferred to the proximal portion of the tibia and is marked accordingly. The proximal cut of the osteot- omy is placed approximately 1 cm below the proximal Steinman pin. The second or inferior cut is made at the appropriate angle to the proximal cut as outlined on the preoperative templates. This may vary from 7 ° to 15 ° depending on the degree of correction desired. When the second osteotomy cut is made, this should allow the inferior cut to exit into the proximal cut before the prox- imal osteotomy cut exits on the medial side. This geom~ etry will reduce or eliminate any significant limb length shortening. The first, or proximal cut, is made parallel to the Steinman pin and is usually performed with the use of a thin-bladed oscillating saw. Palpation on the medial side is performed to insure that the osteotomy is

complete and to prevent any significant damage to the soft tissues. A thin saw blade is placed in this proximal osteotomy cut for guidance as the second cut is made (Fig 3). The second, or distal cut, must be performed care- fully to avoid closing or opening of the osteotomy antero- posteriorly and this saw blade will help in guiding and maintaining the desired angle. The base of this wedge is usually 1 cm in width or approximately l°/mm. As the second osteotomy cut is made, it is not completed but the bone is removed from the lateral side with the use of a Kocher instrument. This allows for improved visualiza- tion as the second osteotomy cut is made, particularly the posterior cortex. This, along with keeping the knee at 90 ° of flexion, should avoid any complications involving the posterior structures of the leg. When all of the bone is removed from the wedge, but before closure of the osteotomy itself, excellent visualization of the posterolat- eral and anterior portion of the tibia is obtained. No attempt is made to perform any significant dissection me- dially, allowing for maintenance of the soft-tissue attach- ments.

Before closure of the wedge, a second Steinman pin is inserted approximately 2 to 3 in below the tibial tubercle from lateral to medial. This is placed so that the two Steinman pins subtend the angle of correction. When closure of the osteotomy has been completed, the pins will become parallel. If there is any difficulty in closing the wedge, further clearance of the posteromedial corner is performed with the use of a fine osteotome. When the posteromedial corner has been completely osteoto- mized, closure is completed. Once closure of the oste- otomy has been obtained, a Charnley compression appa- ratus is placed and the osteotomy site compressed (Fig 4). It is possible, at this time, to provide some decompres- sion of the patellofemoral compartment by displacing the tibia slightly anteriorly. This is not performed routinely. With the osteotomy site compressed, and the knee is flex- ion, the fibular head and peroneal nerve are inspected to confirm that the fibula has been adequately displaced and that the nerve is intact.

At this point, the image intensifier is used to visualize the correction obtained. This is performed before the insertion of the staples if further correction is indicated. The technique for image intensification of the osteotomy

Fig 3. A saw blade placed in the proximal cut guides the distal cut preventing anterior or posterior closure.

114 EVANS AND MADRID

Fig 4. The osteotomy site is compressed using a Charnley compression device,

site is performed using a radiopaque wire (Bovie cord) centered over the femoral head and midankle joint (Fig 5). The image intensifier is then placed directly over the knee joint and the Bovie cord is then seen passing through the lateral compartment, permitting "unload- ing" of the medial compartment (Fig 6). If insufficient correction has been obtained, the Charnley compression apparatus can be released and further bone removed. Compression is then applied and the position again checked with the image intensifier. Once the operator is satisfied that appropriate correction has been obtained and that the osteotomy is compressed, the staples are inserted. This is accomplished with the 3M Bone Stapilizer loaded with 16 x 25 mm staples, placing two staples anteriorly, and three more staples from anterior to posterior on the lateral side (Fig 7). Before placing these last three staples, a portion of the lateral wedge may be fashioned to act as an abuttment graft against the stepoff,

Fig 6. Visualization with C-arm of the wire passing through the lateral compartment.

if this is significant. The compression is released after stapling and stable fixation is confirmed. The Steinman pins are then removed and the image intensifier is again used in both the AP and the lateral plane to be sure that the staples are adequately placed and that there is no penetration of the joint surface. The peroneal nerve is again identified to be sure that there is no impingement and then the Penrose drain is removed. Closure over the staples is performed using the anterior tibial compart- ment fascia. A hemovac drain is placed and further

Fig 5. A Bovie cord is placed from the hip to the ankle joint to assess the new mechanical axis as it passes through the lateral compartment of the knee joint.

Fig 7. Five staples are used for internal fixation of the oste- otomy site.

TREATMENT FOR UNICOMPARTMENTAL ARTHRITIS 1 15

w o u n d closure is per formed. A pressure dressing is ap- plied and the knee is initially immobil ized with a knee immobilizer.

Postoperat ively, the pat ient is placed on a cont inuous passive mot ion device and is also ins t ructed in active range of motion. Within the first 24 hours, the pat ient regains at least 90 ° of flexion, is able to straight-leg raise with the knee immobil izer in place, and is encouraged to walk using crutches and the knee immobil izer wi th touch w e i g h t b e a r i n g . W e i g h t - b e a r i n g ac t iv i ty can be in- creased as tolerated and the pat ient carefully s tudied wi th serial radiographs. In 6 to 8 weeks, the pat ient is often participating in full weight-bear ing activities wi th an al- most normal range of motion.

RESULTS

This p rocedure has been pe r fo rmed in 22 patients with genu v a r u m and osteoarthri t is and two pat ients wi th genu va r um and avascular necrosis. This represents 24 pat ients and 26 knees wi th 7 females and 17 males. The age range was f rom 34 to 63 years with an average age of 49 years. The average t ime to un ion was 7.7 weeks and no nonun ions occurred in this series. Preop- eratively, there was an average of 4 ° of varus angulat ion and the average correct ion was to 6.7 ° of valgus as as- sessed wi th single-stance weight -bear ing films. Only one pat ient lost more than 2 ° of correction. The follow up in this series was 36 to 82 mon ths with no peroneal nerve palsies, infections or nonun ions and no significant loss of correction. Twenty- four of 26 patients had suffi- cient pain relief al lowing them to be more active than before the operat ion. One pat ient has been conver ted to total knee ar throplas ty and the other pat ient has had fair pain relief.

DISCUSSION

This p rocedure provides for a reproducible os teo tomy with rigid fixation, using a un ique staple. With the os- t e o tomy be ing stable, early mot ion , ambula t ion , and

rapid un ion have occurred. High tibial os teo tomy as descr ibed for medial co m p a r tm en t arthri t is allows for significant reduct ion of pain and improved funct ion for patients w h o would otherwise be forced to curtail their activities. This p rocedure allows for simple convers ion to total knee a r t h ro p l a s ty if r equ i r ed in the fu tu re . There are other surgical al ternatives such as meniscal t ransplantat ion, os teochondral t ransplantat ion, and uni- compar tmenta l replacement , but high tibial os teo tomy is the most functional mechanical p rocedure available and should be encouraged in the third to fifth decade of life in patients with significant un icompar tmenta l involvement .

REFERENCES

1. Coventry M: Current concepts review, upper tibial osteotomy for osteoarthritis. J Bone Joint Surg [Am] 67:1136-1140, 1985

2. Sasaki T, Yasuda K: Clinical evaluation of the treatment of osteoar- thritic knees using a newly designed wedged insole. Clin Orthop 221:181-187, 1987

3. Macintosh D, Welsh P: Joint debridement: A complement to high tibial osteotomy in the treatment of degenerative arthritis of the knee. J Bone Joint Surg [Am] 59:1094-1097, 1977

4. Johnson F, Waugh W: Method for routine clinical assessment of knee joint forces. Med Biol Eng Comput 17:145-154, 1979

5. Coventry M: The effect of axial alignment of the lower extremity on articular cartilage of the knee, in Ewing JW (ed): Articular Cartilage and Knee Function: Basic Science and Arthroscopy. New York, NY, Raven, 1990, pp 311-317

6. Insall J, Shoji H, Mayer V: High tibial osteotomy, a five year review. J Bone Joint Surg [Am] 56:1397-1405, 1975

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9. Coventry M: Upper tibial osteotomy. Clin Orthop 182:46-52, 1984 10. Coventry M, Ilstrup D, Wallrichs S: Proximal tibial osteotomy. J

Bone Joint Surg [Am] 75:196-201, 1993 11. Coventry M: Osteotomy of the upper portion of the tibia for degen-

erative arthritis of the knee. J Bone Joint Surg [Am] 47:984-990, 1965

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