Arthroscopic reconstruction of the anterior cruciate ligament using bone-patellar tendon-bone grafts with and without augmentation. A prospective randomised study

In 100 consecutive patients with chronic deficiency of the anterior cruciate ligament we reconstructed the ligament using a bone-patellar tendon-bone autograft either with or without a Kennedy ligament augmentation device. The patients had an aggressive rehabilitation programme supervised by two physiotherapists. They were followed prospectively for at least two years by one surgeon, and assessed after six months and at one and two years. No significant functional or clinical difference was found between the two groups and the stability of the knees did not deteriorate with time in either group. The addition of a Kennedy ligament augmentation device gave no better results than the bone-patellar tendon-bone technique alone.     

Anterior cruciate ligament graft fixation. Initial comparison of patellar tendon and semitendinosus autografts in young fresh cadavers

The initial biomechanical properties of semitendinosus and patellar tendon autografts and their fixation strengths were investigated. Twenty fresh cadaveric knees from donors under 42 years of age were used in the study. After removing all soft tissues other than the anterior cruciate ligament, we determined the ultimate tensile strength (2195 +/- 427 N) and stiffness (306 +/- 80 N/mm) of the anterior cruciate ligament in nine knees. In six knees, anterior cruciate ligaments were reconstructed using an autologous patellar tendon graft with proximal and distal interference fit screws; this resulted in an ultimate tensile strength of 416 +/- 66 N. Five knees were reconstructed with quadruple-stranded (double-looped) semitendinosus tendons fixed proximally by a titanium button and braided tape and distally by tibial post screw. This resulted in an ultimate tensile strength of 612 +/- 73 N, which was significantly higher than the strength in the patellar tendon group. Graft stiffness did not differ between the groups and was 47 +/- 19 N/mm (N = 11). This study demonstrates that the reconstructed knees had only 20% to 30% of the ultimate tensile strength of the normal anterior cruciate ligament. In summary, the semitendinosus reconstruction using a button for proximal fixation is, at the time of surgery, approximately 50% stronger than patellar tendon reconstructions with similar stiffness.     

Anterior cruciate ligament reconstruction with autogenous patellar tendon graft in patients with articular cartilage damage

To test if anterior cruciate ligament reconstruction with autogenous patellar tendon can alleviate symptoms and functional limitations and increase activity levels in patients with advanced articular cartilage damage, we looked at 53 patients with arthroscopically documented cartilage damage. In this group, a mean of 7.5 years had elapsed between the original injury and the reconstruction, and 90 prior operative procedures had been done. Postoperatively, all patients had immediate motion and early functional rehabilitation. The results were assessed with the Cincinnati Knee Rating System. At followup (mean, 27 months), significant improvements were found for pain, swelling, giving way, functional limitations with daily and sports activities, and the overall rating score. Forty-two patients (79%) had returned to some type of athletic activity. Only three patients (6%) had failed results. In the patients' own ratings of the overall knee condition, 8 of 51 (16%) rated their knees as normal, 28 (55%) as very good, 7 (14%) as good, 5 (10%) as fair, and 3 (6%) as poor. We concluded that the majority of patients benefited from the arthroscopically assisted anterior cruciate ligament reconstruction because it decreased episodes of giving way with daily activities and increased activity without aggravating the preexisting arthrosis.     

Anterior knee laxity and loss of extension after anterior cruciate ligament injury

This study was performed to examine the relationship between knee extension loss and the length of time after injury. We also wanted to compare anterior laxity in anterior cruciate ligament-injured knees in the early and late stages of injury. Loss of knee extension was measured in 81 patients with anterior cruciate ligament injury using lateral radiography with the injured leg relaxed and elevated. Extension loss was defined as the difference in maximal extension angle between the injured and uninjured knees. Average loss of extension was 3.6 degrees in the 17 knees in which the anterior cruciate ligament had been torn 3 weeks or less before examination (the acute injury group) and 0.6 degree in the 64 knees in which the anterior cruciate ligament had been torn more than 3 weeks before examination (the chronic injury group). The extension loss in the acutely injured knees was significantly greater compared with that in the uninjured knees and in the chronically injured knees. Arthrometric measurements using the KT-1000 arthrometer were reliable to diagnose an acute tear. There was no correlation between the degree of extension loss and arthrometric anterior knee laxity measurements. In 12 patients, the initial extension deficit in the early stage of injury significantly resolved with time, and manual maximum arthrometric measurements of anterior knee laxity improved spontaneously with time.     

The effects of knee reconstruction on combined anterior cruciate ligament and anterolateral capsular deficiencies

We tested the effect of intraarticular reconstructions of the anterior cruciate ligament alone and in combination with extraarticular reconstructions in 10 cadaveric knees. These knees had anterior cruciate ligament deficiency alone or in combination with anterolateral capsuloligamentous deficiencies. In the knees with combined injury, intraarticular reconstruction returned anterior stability to levels not significantly different from levels found for the knees deficient in the anterior cruciate ligament alone and treated with this procedure. After intraarticular reconstruction, rotational stability of the knee with combined injuries failed to return to the levels seen in the knee with isolated anterior cruciate ligament deficiencies that underwent the same treatment. When a tenodesis with either 0 N or 22 N of tension was added to the intraarticular reconstruction in the knee with combined injuries, we found that excessive internal rotation significantly decreased at all angles of flexion, except at full extension with 0 N of tension. In addition, the extraarticular reconstruction with 22 N of tension in the tenodesis overconstrained the knee in internal rotation between 30 degrees and 90 degrees of knee flexion. The tenodesis with 0 N of tension overconstrained the knee at only 60 degrees and 90 degrees of flexion. These results suggest extraarticular reconstruction as an adjunct to the intraarticular operation for the knee with anterior cruciate ligament and anterolateral structural injuries. The results also suggest that the surgeon can affect anterior and rotational laxity by adjusting the tension in the tenodesis.     

Placental restriction alters adrenal medullary development in the midgestation sheep fetus

This is a retrospective study of 10 patients with combined cruciate ligament and posterolateral instability who underwent surgical reconstruction between 1991 and 1994. All knees had at least 20 degrees increased external rotation at 30 degrees of knee flexion and from 1+ to 3+ varus instability. Five knees with posterior cruciate ligament ruptures had at least a 2+ Lachman test result. (One knee had both anterior and posterior cruciate ligament injuries). In all cases the lateral collateral ligament was reconstructed with a bone-patellar tendon-bone allograft secured with interference screws. Fixation tunnels were placed in the fibular head and at the isometric point on the femur. The cruciate ligaments were reconstructed with autograft or allograft material. The average follow-up was 28 months. Excessive external rotation at 30 degrees of flexion was corrected in all but one knee. Six patients had no varus laxity, and four patients had 1+ varus laxity at 30 degrees of flexion. The posterior drawer test result decreased, on average, to 1+, and the Lachman test result decreased to between 0 and 1+. The average Tegner score was 4.6, with five patients returning to their preinjury level of activity and four returning to one level lower. These results indicate that this is a promising new procedure for patients with instability resulting from lateral ligament injuries of the knee.     

Infrapatellar contracture syndrome. Diagnosis, treatment, and long-term followup

Infrapatellar contracture syndrome is an uncommon but recalcitrant cause of reduced range of motion after knee surgery or injury. The results and conclusions presented here are based on a retrospective clinical study evaluating the long-term outcome in 75 patients who developed infrapatellar contracture syndrome. These 75 patients (76 knees) were evaluated at an average followup of 53 months after the index (inciting) procedure or injury. Comparing subgroups within the study population, factors that correlated with poorer results or more severe infrapatellar contracture syndrome were found to be acute anterior cruciate ligament repair or reconstruction, the use of patellar tendon autograft for anterior cruciate ligament reconstruction, nonisometric graft placement, multiple surgical procedures, use of closed manipulation, and the development of patella infera. We concluded that appropriate procedures can substantially increase the range of motion in patients with infrapatellar contracture syndrome. However, residual functional morbidity persists in many patients, and the outcome, as determined by subjective knee function scores, is only fair. The natural history of an anterior cruciate ligament-deficient knee appears to be more benign than the natural history of a knee that develops infrapatellar contracture syndrome.     

A comparison of results in acute and chronic anterior cruciate ligament ruptures of arthroscopically assisted autogenous patellar tendon reconstruction

We conducted a prospective study of 94 consecutive patients who received a patellar tendon autograft for anterior cruciate ligament rupture. Eighty-seven patients (93%) returned for followup a mean of 28 months postoperatively; 57 had chronic and 30 had acute or subacute ruptures. There were no significant differences between the subgroups for age, sex, articular cartilage lesions, or months of followup. Forty-six meniscal tears were repaired; 27 of these extended into the central avascular region. Rehabilitation emphasized immediate knee motion, but strenuous activity was delayed for at least 4 months. Only one patient had a knee motion complication, and stability (<3 mm, KT-2000 arthrometer, 134 N) was restored in 85% of knees with chronic ruptures and 92% of knees with acute ruptures. Earlier reconstruction should be considered in active persons as symptoms and limitations continued postoperatively in knees with chronic ruptures, leading to overall less satisfactory results. In patient rating of the overall knee condition, 69% of knees with chronic ruptures and 100% of knees with acute ruptures scored in the normal or very good range. Repair of meniscal tears that extend into the central avascular region should be considered, as 24 of the 27 (89%) menisci repaired showed clinical evidence of healing and did not require reoperation.     

Evaluation of hamstring strength following use of semitendinosus and gracilis tendons to reconstruct the anterior cruciate ligament

Reconstruction of the anterior cruciate ligament using the semitendinosus and gracilis tendons combined with the appropriate extraarticular procedures has been performed by the authors in 482 cases. In 321 cases both the semitendinosus and gracilis tendons were used and in 161 the semitendinosus alone. This retrospective study was done to determine if the use of these two tendons resulted in any significant loss of hamstring strength. Evaluation of quadriceps strength was also done as a measure of postoperative rehabilitation. Fifty-one patients with an average follow-up time of 26.2 months were tested on the Cybex machine (Cybex Co., Ronkonkoma, New York) by two examiners using the same technique. The examiners had not participated in the surgery or rehabilitation of these patients. In the reconstructed knee in which both semitendinosus and gracilis were used, hamstring strength was found to average 99% compared to the normal knee. When the semitendinosus alone was used there was no difference (102%) from the normal knee. Quadriceps strength in both groups averaged 96% in comparison to the normal quadriceps. These results confirm that no significant loss of hamstring strength occurred when the semitendinosus and gracilis tendons were used to construct the anterior cruciate ligament. Further, quadriceps strength of 96% as compared to the normal knee indicated a very acceptable degree of postoperative rehabilitation in this series.     

Outpatient ACL reconstruction using intraoperative local analgesia and oral postoperative pain medication

Thirty-five consecutive anterior cruciate ligament (ACL) reconstructions were performed in an ambulatory surgical unit using a bone-patellar tendon-bone autograft. Patients were evaluated postoperatively to determine the amount of pain medication used, the readmission rate, postoperative complications, and cost. Outpatient ACL reconstruction led to a savings of $4700 compared with the cost of performing the same procedure in a hospital operating room with an overnight admission. This study demonstrates that outpatient ACL reconstruction, using local analgesia intraoperatively and oral narcotic pain medication postoperatively, is a safe and cost-effective procedure with minimal to no morbidity.     

Acute repair of injury to the anterior cruciate ligament. A long-term followup

We reviewed 30 patients at an average of 7.4 years after acute repair of the anterior cruciate ligament augmented with a loop of iliotibial tract. A noncontact twisting had been the mechanism of injury in 18 of these patients, with 28 having been injured in sports. At followup, 25 patients had not experienced symptoms of instability and 23 were able to return to unrestricted athletic activity; only 5 had been unable or unwilling to return to sporting activity at all. There had been no swelling in 23 patients; however, 17 suffered from pain on exertion. The average Lysholm score was 93.2. Joint laxity was assessed and anteroposterior tibial translation quantified with a KT-1000 arthrometer. Eighteen patients had a normal or 1+ Lachman test and 27 had an absent or 1+ pivot shift. When compared with the results of a similar study performed on this group of patients at 2 years after surgery, there had been little subjective change in knee function. However, objectively there had been significant deterioration of the anteroposterior stability of the knees at 7 years, suggesting failure of the integrity of the repaired ligament with time. An associated medial collateral ligament injury had a significant adverse effect both on the integrity of the anterior cruciate ligament repair and the incidence of postoperative stiffness.     

Meniscal allograft transplantation for unicompartmental arthritis of the knee

Sixty-seven meniscal allografts were transplanted in the knees of 63 patients between 1988 and 1994. Before surgery, all patients experienced refractory disabling knee pain secondary to a prior total meniscectomy with advanced unicompartmental osteoarthritic changes as verified by arthroscopy. At a mean followup of 31 months (range, 1.0-5.5 years), 58 knees (86.6%) attained a good to excellent results-Twenty-one knees received isolated meniscal allografts, with 19 achieving good to excellent results (90.5%). Five knees received a medial or lateral meniscal allograft with an anterior cruciate ligament reconstruction, and 4 (80.0%) obtained good to excellent results. Thirty-four knees received a meniscal allograft in combination with either a valgus high tibial osteotomy, varus high tibial osteotomy, or varus distal femoral osteotomy to correct for preoperative varus or valgus deformities, with 29 (85.3%) attaining good to excellent results. The remaining 7 knees underwent a combined medial meniscal allograft, valgus high tibial osteotomy, and anterior cruciate ligament reconstruction with 6 (85.7%) attaining good to excellent results. The most frequent complication was a traumatic posterior horn tear in 6 knees at a mean of 21 months after surgery (range, 9-43 months), most likely the consequence of unsuccessful healing of the posterior horn of the graft.     

The effect of immediate weightbearing after anterior cruciate ligament reconstruction

Immediate weightbearing has been advocated after anterior cruciate ligament reconstruction and is thought to enhance the return of quadriceps muscle activity and knee extension range of motion without jeopardizing graft integrity. This study examined the effect of immediate weightbearing after anterior cruciate ligament reconstruction on the return of vastus medialis oblique electromyography activity, knee extension range of motion, knee stability, physical examination, Lysholm score, and anterior knee pain. Forty-nine patients (24 men and 25 women) undergoing endoscopic central third patella tendon autograft reconstruction were randomized prospectively into two groups. Group 1 patients underwent immediate weightbearing as tolerated. Group 2 patients were kept nonweightbearing for 2 weeks. All measurements were taken before surgery, 2 weeks after surgery, and between 6 and 14 months (average, 7.3 months) followup. There was no effect of weightbearing on knee extension range of motion or vastus medialis oblique function at followup. In addition, knee stability was not compromised after surgery. Seven of 20 (35%) nonweightbearing patients and only two of 25 (8%) immediate weightbearing patients reported anterior knee pain at followup. Overall, immediate weightbearing did not compromise knee joint stability and resulted in a better outcome with a decreased incidence of anterior knee pain.     

Orthopaedic implant infections: current management strategies

A small femoral notch width index has been reported as a predictive factor for anterior cruciate ligament injury and implicated in the higher incidence of anterior cruciate ligament injuries in female athletes. Notch-plasty has been recommended for the unaffected knees of patients who have torn one anterior cruciate ligament and whose notch width index falls one standard deviation below "normal". However, the symmetry of the notch width index has not been specifically studied. We compared the notch width index in both knees of 40 male and 40 female patients. Half of the patients in each group had anterior cruciate ligament injuries, all from a noncontact mechanism. We found that the notch width indexes of the right and left knees of the same patient are essentially symmetrical, regardless of sex or anterior cruciate ligament status. Although the female patients tended to have smaller notch width indexes than the male patients, the difference was not statistically significant. Moreover, the ranges of notch width indexes in male and female patients overlapped considerably. Finally, there was no difference in notch width index between patients with and without anterior cruciate ligament tears. These findings suggest that the notch width index alone is not the critical etiologic factor in the patient with a unilateral anterior cruciate ligament tear. Furthermore, the increased incidence of anterior cruciate ligament tears in female patients compared with male patients in the same sports cannot be attributed to notch width index alone.     

Effects of cold and compression dressings on early postoperative outcomes for the arthroscopic anterior cruciate ligament reconstruction patient

Efforts to minimize the morbidity of anterior cruciate ligament (ACL) reconstruction include the use of cryotherapy and/or compressive dressings in the immediate postoperative period. We undertook the present study to determine if the alleged benefits of the Cryo/Cuff, which combines these modalities, are more attributable to its compressive effect rather than cold application. Seventy-eight patients admitted for primary endoscopic ACL reconstruction using a bone-patella tendon-bone autograft were randomized to receive Cryo/Cuff compressive dressings postoperatively. Forty subjects (Group 1) had the cuff applied with continuous circulating ice water using the Autochill device, while 38 others (Group 2) received the cuff with room temperature water. Cases were performed as inpatients and all subjects were administered intravenous morphine postoperatively via a patient-controlled infusion pump for the first 24 postoperative hours. At baseline, the groups were well matched in age, sex, duration of symptoms, operative time, and associated meniscal surgery. No significant difference between groups was detected with respect to length of hospitalization, Hemovac knee drainage, oral and intravenous narcotic requirement, or subjective pain as measured by a visual analog scale. No apparent complications related to the use of the Cryo/Cuff dressings were noted. The clinical effect of the Cryo/Cuff in this study was not influenced by the use of continuous ice water vs. room temperature water. Further study should focus on variations in compression to evaluate the clinical impact of this device.     

Bone tunnel enlargement after anterior cruciate ligament reconstruction with semitendinosus tendon using Endobutton fixation on the femoral side

We evaluated 29 knees with a minimum follow-up of 2 years after anterior cruciate ligament (ACL) reconstruction using doubled autogenous semitendinosus tendons. On the femoral side, a 5-mm Mersilene tape (Ethicon, Norderstedt, Germany) with an Endobutton (Acufex Microsurgical, Mansfield, MA) was used. The tendon was fixed on the tibial side with two staples. Regarding the IKDC score, 66% of the patients were graded as normal or nearly normal. The anterior laxity side-to-side difference (KT 1000, man-max-drawer) was under 3 mm in 55% and under 5 mm in 90%. Radiographs taken in the lateral and anteroposterior projections of the knee showed sclerotic bone tunnel margins. The diameter of the bone tunnels were measured, corrected for magnification, then compared with the original reamed diameter to determine any change in size. Enlargement of at least 2 mm was identified in 72% of the femoral tunnels and 38% of the tibial tunnels. No correlation was found concerning the enlargement of the tunnel and the IKDC score or the residual joint laxity. We conclude that using an Endobutton-Mersilene construct in ACL reconstruction leads to femoral and tibial bone tunnel enlargement at follow-up of 2 years.     

Comparison of arthroscopic and open reconstruction of the anterior cruciate ligament. Early results

The purpose of this study was to determine in a prospective, randomized, blinded design whether arthroscopically assisted anterior cruciate ligament reconstruction offered any significant immediate or short-term advantages over traditional open reconstruction through a limited arthrotomy. Patients with a diagnosis of deficiency of the anterior cruciate ligament were randomly assigned to one of two treatment groups: the open group (limited open reconstruction) or the arthroscopic group (fully arthroscopic reconstruction). Postoperatively, both groups were treated identically. Intra- and postoperative observations included length of surgery, duration of hospitalization, and amount of pain medication. Follow-up evaluations were performed at 1, 6, 12, 16, 20, and 24 weeks to record crepitus, swelling, range of motion, ligament laxity, and thigh atrophy. Lysholm scores were obtained at the 16 and 24 week follow-ups. At 24 weeks, 86% of the open group and 89% of the arthroscopic group had good-to-excellent results. Intraoperative, postoperative, and follow-up findings indicated no statistically significant differences or relationships between the two groups in any of the variables measured, except that operative time was 13 minutes longer in the arthroscopic group (P < 0.001). The results do not substantiate a clinical advantage for either technique.     

Effect of external extra-articular ligament plasty on the results of anterior cruciate ligament reconstruction with patellar tendon, a 4 years follow-up

PURPOSE OF THE STUDY: The purpose of this study was to compare the functional results obtained when an external extra-articular plasty was added to an anterior cruciate ligament (ACL) reconstruction using an autologous bone tendon-bone patellar tendon graft. MATERIAL AND METHODS: The authors analyzed two consecutive series of 60 and 50 patients operated by the same surgeon for a chronic rupture of the anterior cruciate ligament, one by reconstruction of the cruciate ligament with a free graft of the patellar tendon supplemented by an external extra-articular plasty made with a quadriceps tendon graft and the second with an isolated free patellar tendon graft. Anterior laxity was measured before and after surgery, by dynamic X-rays and by the Medmetric KT-1000 arthrometer. Functional results were evaluated four years after operation, with the French A.R.P.E.GE score based on sport activity level and intensity. RESULTS: Anterior laxity was not different before operation in both groups and there was no difference between males and females. Medmetric KT-1000 arthrometer showed the same negative differential laxity immediately after surgery in both groups and the same evolution during the first 4 years, without any significant difference on laxity on the middle aspect of the knee. Radiological results were different. After a 4 years follow-up, anterior laxity did not show significant difference on the medial compartment of the knee (5.3 +/- 2.3 mm and 5.5 +/- 1.7 mm), but there was a significant minor laxity in the lateral compartment for the lateral extra-articular plasty group (11.0 +/- 2.3 mm against 14.8 +/- 3.8 mm)(p = 0.002). Functional results and sport activity were similar in both groups. Examination showed 4 positive pivot shift tests (2 "sliding" and 2 positive) in the group with extra-articular plasty, even though 8 positive pivot shift tests in the isolated ACL group (5 "sliding" and 3 positive) were found. DISCUSSION: This study, as well as five others studies found in literature, was not randomized. In all these series, the surgical techniques, the rehabilitation programs and the functional score evaluation were too different to allow any pertinent comparison. Extra-articular plasty helps to control the laxity of the lateral compartment of the knee which is incompletely controlled by ACL reconstruction, particularly in chronic cases. This is proved by radiological measurements and pivot shift tests. Jensen in 1983, about 205 patients with a 4 year follow-up and Noyes, which used an allograft patellar tendon, found an advantage to do extra-articular plasty. But Strum (in 1989), as O'Brien (in 1991) and Roth (in 1987), did not found any advantage with extra-articular plasty. CONCLUSION: It is therefore obvious, after a four-year follow-up, that extra-articular supplementation presents an advantage for reconstruction of the ACL. by a free graft of the patellar tendon in chronic cases. Further randomized study will confirm that isolated ACL reconstruction is possible in some well defined categories of anterior laxity.     

The semitendinosus tendon as replacement for the anterior cruciate ligament

This article describes the history, advantages, biomechanical properties, operative technique, and results of replacement of the anterior cruciate ligament using the semitendinosus tendon. After arthroscopic ACL replacement using the doubled semitendinosus tendon in combination with an extraarticular lateral repair in 65 consecutive patients (20 acute, 45 chronic instabilities) we found after 2 years in 51 patients (78%) an excellent or good result with less than 3 mm difference in the Lachman test measured with the KT-1000 arthrometer (MMD). After 6 years 40 out of the 45 patients with chronic instabilities could be examined again. Only 28 patients (70%) showed a difference in anterior translation of less than 3 mm. A positive pivot shift sign could be seen in 11% of the patients after 2 years and in 20% after 6 years. The Tegner score increased from 6.0 after 2 years to 6.2 after 6 years, the Lysholm score decreased from 93 to 91 in the same interval. 89% of the patients had a free range of knee motion after 2 years and 92.5% after 6 years. There were 10% normal, 50% nearly normal, 25% abnormal, and 15% severely abnormal knees in the IKDC evaluation after 6 years. In the last 4 years we are using the quadrupled semitendinosus tendon in an arthroscopic single incision technique for ACL replacement with femoral Endobutton fixation, because the doubled semitendinosus tendon seems to elongate over time. After 23 months on average (12-36 months) the preoperative anterior translation of 7.5 mm could be decreased to 1.9 mm in 35 patients.     

Prospective preoperative evaluation of anterior cruciate ligament instability of the knee joint and results of reconstruction with patellar ligament

Of 54 patients with chronic (n = 49) or acute (n = 5) anterior cruciate ligament instability, 52 were evaluated after mean 16 months' follow-up interval after open (n = 18) or arthroscopic assisted (n = 36) bone-tendon-bone patellar ligament reconstruction. Preoperative Knee Signature System side-to-side difference in anterior displacement decreased from 7.9 mm to 3.5 min at follow-up evaluation (p < 0.0001). An objectively satisfactory limit of 5 mm in side-to-side difference was achieved in 73% of the patients. At follow-up evaluation, there was a positive pivot shift sign in eight knees (one definite and seven trace). Average Lysholm knee scores improved from 69 to 83. The only significant difference between the arthroscopic assisted and open groups was smaller side-to-side anterior displacement difference in the arthroscopic group (2.2 mm versus 4.8 mm, p = 0.002). Results suggest that more accurate and isometric placement of the graft is possible with the arthroscopic-assisted technique.