Tibia1 Interference Screw Removal Following Anterior Cruciate Ligament Reconstruction

Peter R. Kurzweil, M.D., Anthony D. Frogameni, M.D., and Douglas W. Jackson, M.D.

Summary: A small number of patients developed pain and tenderness at the tibia1 tunnel following anterior cruciate ligament reconstruction. Twenty-three knees in 22 patients underwent removal of the tibia1 interference screw. Ten knees had a preoperative Aexion contracture and underwent a concomitant procedure to address the loss of motion at the time of hardware removal. In the 13 knees with full extension, the interval between ligament reconstruction and screw removal aver- aged 16 months. Eleven of these knees also underwent arthroscopy, but no intra- articular causes of pain were identified. Roentgenographic analysis showed protm- sion of the interference screw above the tibia1 cortex in three cases. Follow-up after hardware removal averaged 2 years. Tibia1 tunnel tenderness resolved in 21 of 23 knees, including those of the two patients who underwent hardware removal alone. Although it cannot be stated with certainty that tibia1 interferences screws may cause pain, this review suggests an association. This is an uncommon problem and it is estimated to be a factor in less than 3% of the authors’ anterior cruciate ligament reconstructions. More common causes of knee pain should be sought before electing to remove the tibia1 interference screw. Key Words: Interference screw-Painful hardware-Anterior knee pain.

F ixation of bone-patellar tendon-bone autografts with interference screws has become a popular

technique in anterior cruciate ligament (ACL) recon- structions. Other methods of fixation, such as suturing, staples, and screw/washer combinations, have met with various success over the years.le5 However, complica- tions of these techniques, including fixation failure, hardware breakage, tissue necrosis, loosening, bony fractures, and painful hardware, have also been de- scribed.4x6-9

To avoid these complications and take advantage of bone-to-bone fixation,’ interference screws have been used. However, a small number of our patients devel- oped pain and tenderness at the tibia1 tunnel site neces-

From the Southern California Center for Sports Medicine, Long Beach, California, U.S.A.

Presented at 60th Annual Meeting of the American Academy of Orthopaedic Surgeons, San Francisco, California, February 1993.

Address correspondence and reprint requests to Peter R. Kurz- weil, M.D., 2760 Atlantic Ave, Long Beach, CA 90806, U.S.A.

0 1995 by the Arthroscopy Association of North America 0749.8063/95/1103-1030$3.00/O

sitating screw removal. The purpose of this article is to estimate the incidence of interference screw removal and try to elucidate factors that may contribute to this problem. To the knowledge of the authors, this is the first report of pain associated with interference screws.

MATERIALS AND METHODS

Between 198X and 1990, the senior author (D.W.J.) performed 458 ACL reconstructions using bone-patel- lar tendon-bone autografts and allografts. Fixation was achieved in nearly all cases with femoral and tibia1 interference screws. Because a screw and washer com- bination was used occasionally, the authors conserva- tively estimate that interference screws were used in 95% of the cases. Twenty-three knees in 22 patients came to the attention of the authors because of persis- tent pain over the tibia1 tunnel site. Autografts were used in all but two patients.

The pain was characterized by a vague ache over the anteromedial aspect of the knee in the region of

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290 P. R. KURZWEIL ET AL.

the tibial tunnel extra-articular opening. The symptoms were frequently exacerbated by strenuous weight-bear- ing activity. Nonsteroidal anti-inflammatory medica- tion provided mild, temporary relief in only a few pa- tients. The pain was generally unaffected by bracing and physical therapy. Each patient had tenderness over the tunnel site, which varied from mild to marked. None of the knees showed a significant difference in side-to-side anterior tibial translation with the KT- 1000. Ten of the 23 knees (43%) lacked full extension.

Radiographic evaluation revealed nothing unusual about the position of the tibia1 screws or adjacent bony plugs. There were no cysts in the tunnels and the plugs appeared to have incorporated in all cases. Most screws were buried deep within the tibia1 tunnel except in three knees where radiographs showed screw protru- sion above the cortical surface.

The mean interval from ligament reconstruction to screw removal was 12 months (range 4 to 36 months). The patients whose chief problem was a flexion con- tracture were generally operated on earlier to regain extension. All but two patients underwent arthroscopic evaluation at the time of hardware removal.

Finding the screw during surgery was difficult when the tibia1 tunnel opening was covered by bone. Intraop- erative use of the fluoroscan (mini-C-arm) was helpful in locating screws buried deep in the tunnel. A distinct bursal sac had formed over the screw in three patients.

RESULTS

Follow-up evaluation was performed 2 years after screw removal (range, 24 to 40 months) and at least 3 years after ACL reconstruction (range, 3 to 5 years). Pain and tenderness over the tibia1 tunnel site were eliminated in 21 of the 23 patients. This includes the two patients who underwent hardware removal without concommitant arthroscopy.

Continued symptoms in two patients could not be readily explained. One patient had undergone allograft reconstruction following a failed autograft. She had persistent anteromedial discomfort and a small effu- sion, although no tenderness at the site of screw re- moval. The other patient had mostly retropatellar pain, but the tibia1 tunnel site still ached. A bone scan showed increased activity along the drilled tunnels as well as findings consistent with mild to moderate de- generative joint disease.

DISCUSSION

Hardware complications after ACL reconstruction are known, but infrequently mentioned in the litera-

ture.4,6-9 Painful hardware has been noted chiefly with screw and washer combinations, where a prominent screw head can irritate the overlying tissue. Graf and Uhr7 used a screw and washer for graft fixation and found 8% of their 103 patients complained of pain at the tibia1 hardware site following ACL reconstruction. Interference screws are headless, and theoretically avoid subcutaneous irritation. They are also superior to other methods of fixation in terms of pullout strength.5

Despite its potential advantages, interference screw fixation has been associated with some complications. Matthews and Soffer’ reported inadvertent graft ad- vancement, damage to the passing sutures in the bone plugs, and graft-tendon laceration.

In the present study, pain and tenderness at the tibia1 tunnel site was found to be another potential problem. The symptoms resolved in 21 of 23 knees (91%) fol- lowing removal of the interference screw. The cause of pain from the tibia1 interference screw is not clear. In only 3 of 23 cases was there radiographic evidence of screw protrusion, suggesting that mechanical irrita- tion of the overlying tissue is an infrequent cause. The close proximity of the pes anserine to the tibia1 drill hole may result in a painful bursitis. A distinct bursa was found covering the screw site in three patients. Schatzker et al.’ found bony necrosis associated with compression screws, although this has not been re- ported with interference screws. We performed a bi- opsy on the bone from the tibia1 tunnel in two cases during hardware removal and found no bony necrosis.

Although it cannot be conclusively stated that tibia1 interference screws can cause discomfort, this review suggests an association. However, routine removal of this screw in a patient with anterior knee pain follow- ing ACL reconstruction is not recommended. A careful evaluation should seek more common causes, such as arthrofibrosis or patellofemoral problems, before contemplating hardware removal.

Only 23 of the 458 patients undergoing ACL recon- struction eventually underwent removal of the tibia1 interference screw. Assuming that interference screws were used in 95% of the cases, we estimate that the tibia1 interference screw was removed in approxi- mately 5%. This estimation is worthwhile because pa- tients frequently inquire whether the screw ever has to be removed. Similar problems with the femoral inter- ference screw have not been identified.

As a result of our experience, we have made two minor changes during ACL reconstruction. First, every effort is made to completely bury the end of the screw beneath the cortex, avoiding any prominence that may irritate the overlying tissue. This can be facilitated by

TIBIAL INTERFERENCE SCREW REMOVAL 291

avoiding graft-tunnel mismatch.” Second, a l-inch tail of the permanent suture is left in the tibia1 bone plug. This acts as a marker to guide the surgeon back to the tibia1 tunnel entrance should subsequent screw removal be necessary.

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