The effect of early motion on tibial tunnel widening after anterior cruciate ligament replacement using hamstring tendon grafts

Tunnel widening after anterior cruciate ligament reconstruction: a prospective randomized computed tomography--based study comparing 2 different femoral fixation methods for hamstring graft

PURPOSE

We prospectively sought to compare the incidence and properties of tunnel widening in patients undergoing anterior cruciate ligament reconstruction with quadrupled hamstring graft by use of either EndoButton CL (Smith & Nephew Endoscopy, Andover, MA) or Transfix (Arthrex, Naples, FL) on the femoral side with a bioabsorbable interference screw in the tibial tunnel by computed tomography scan.

METHODS

We included 34 patients in the study and randomized them into 2 groups--EndoButton and Transfix groups. An anteromedial portal technique was used to create the femoral tunnels in the EndoButton group, whereas a transtibial technique was used in the Transfix group. A bioabsorbable screw was used on the tibial side in both groups. Thirty patients completed the study protocol, and assessment was done at regular intervals until 12 months of follow-up was reached. The patients underwent computed tomography scans at 2 weeks, 3 months, and 6 months postoperatively. The diameters of the tunnels were measured perpendicular to the long axis of the tunnels on oblique coronal and oblique sagittal planes at 3 levels: aperture, midway, and suspension point. We performed functional scoring with the International Knee Documentation Committee 2000 Subjective Knee Evaluation score and Lysholm score.

RESULTS

Femoral tunnel widening at the aperture and at midway was significantly greater in the EndoButton group compared with the Transfix group. A decrease in the loop length in the EndoButton group was associated with lesser tunnel widening, although this was not found to be statistically significant with the numbers available. A trend toward decreased tunnel widening at the aperture on the tibial side was observed when the tip of the screw was 10 to 15 mm away from the aperture.

CONCLUSIONS

Femoral tunnel widening was significantly less in the Transfix group compared with the EndoButton group.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Femoral tunnel enlargement after anatomic ACL reconstruction: a biological problem?

Tunnel enlargement after anterior cruciate ligament (ACL) reconstruction may compromise revision surgery. The cause of this tunnel enlargement is not yet fully understood, but it is thought to be multifactorial, with biomechanical and biological factors playing a role. Tunnel enlargement has been described particularly in patients who underwent ACL reconstruction with hamstring tendons with extracortical fixation devices. The purpose of our study was to evaluate prospectively with magnetic resonance imaging (MRI) the changes in femoral tunnel diameter following arthroscopic anatomic ACL reconstruction with hamstring tendons. At 3-month post-op, all tunnels had enlarged compared to the diameter of the drill and most tunnels enlarged more in the midsection than at the aperture. In the posterolateral tunnels, the entrance increased 16% in diameter and the middle of the tunnel increased 30% in diameter. In the anteromedial femoral tunnels, the tunnels enlarged 14% at the aperture and 35% in the midsection. All femoral tunnels enlarged and most of them enlarged in a fusiform manner. The biological factors explain better our findings than the mechanical theory, although mechanical factors may play a role and the cortical bone at the entrance of the tunnel may modify the way tunnels respond to mechanical stress.

Osseous deficits after anterior cruciate ligament injury and reconstruction: a systematic literature review with suggestions to improve osseous homeostasis

PURPOSE

This systematic review was performed to improve our understanding of the current evidence regarding the influence of anterior cruciate ligament (ACL) injury and reconstruction on involved lower extremity apparent bone mineral density, bone content, or bone area mass (bone integrity).

METHODS

Two independent reviewers performed a Medline search from 1966 to January 2010 using the terms "anterior cruciate ligament" or "ACL" combined with "wound" or "injury" and "bone density" or "osteoporosis." Study inclusion criteria were English-language human studies. Reference sections of selected studies were also reviewed.

RESULTS

Ten studies were identified that met our inclusion criteria. Eight studies performed ACL reconstruction with bone-patellar tendon-bone autografts and interference screw fixation. One study performed ACL reconstruction by use of Achilles tendon allografts with interference screw and staple fixation. Two ACL injury studies either did not involve ACL reconstruction or attempted primary repair with sutures. All studies reported varying levels of decreased bone mineral density, bone content, or bone area mass (bone integrity) at the involved lower extremity after ACL injury that did not return to premorbid levels even with ACL reconstruction and rehabilitation. Sites of reduced bone integrity included the proximal and distal femur, proximal tibia, patella, and calcaneus. Bone loss was increased with limited weight bearing and prolonged disuse or immobilization; however, significant improvements were not observed with accelerated rehabilitation. Some studies reported relations between Lysholm, Tegner, International Knee Documentation Committee survey, or function scores and bone integrity, whereas others reported no or poor relations.

CONCLUSIONS

Involved lower extremity bone integrity is decreased after ACL injury. Current evidence suggests that premorbid bone integrity is not re-established after ACL reconstruction even when accelerated rehabilitation is performed. Recommendations to improve osseous homeostasis and bone health after ACL injury and reconstruction are provided.

Comparison of plain radiography, computed tomography, and magnetic resonance imaging in the evaluation of bone tunnel widening after anterior cruciate ligament reconstruction

Bone tunnel widening poses a problem for graft fixation during revision anterior cruciate ligament (ACL) reconstruction. Large variability exists in the utilization of imaging modalities for evaluating bone tunnels in pre-operative planning for revision ACL reconstruction. The purpose of this study was to identify the most reliable imaging modality for identifying bone tunnels and assessing tunnel widening, and specifically, to validate the reliability of radiographs, MRI, and CT using intra- and inter-observer testing. Data was retrospectively collected from twelve patients presenting for revision ACL surgery. Five observers twice measured femoral and tibial tunnels at their widest point using digital calipers in coronal and sagittal planes. Measurements were corrected for magnification. Tunnel identification, diameter measurements, and cross-sectional area (CSA) calculations were recorded. A categorical classification of tunnel measurements was created to apply clinical significance to the measurements. Using kappa statistics, intra- and inter-observer reliability testing was performed. CT demonstrated excellent intra- and inter-observer reliability for tunnel identification. Intra- and inter-observer reliability was significantly less for MRI and radiographs. CT revealed superior reliability versus either radiographs or MRI for CSA analysis. Intra-observer kappa scores for tibial CSA using CT, radiographs, and MRI were 0.66, 0.5, and 0.37, respectively. Inter-observer kappa scores for tibial CSA using CT, radiographs, and MRI were 0.65, 0.39, and 0.32, respectively. Our results demonstrate CT is the most reliable imaging modality for evaluation of ACL bone tunnels as proven by superior intra- and inter-observer testing results when compared to MRI and radiographs. Radiographs and MRI were not reliable, even for simply identifying the presence of a bone tunnel.

Differentiation between intraoperative and postoperative bone tunnel widening and communication in double-bundle anterior cruciate ligament reconstruction: a prospective study

PURPOSE

The purpose of this study was to determine the amount of intraoperative and postoperative bone tunnel enlargement and communication in double-bundle (DB) anterior cruciate ligament (ACL) reconstruction.

METHODS

Twenty-four consecutive patients undergoing anatomic anteromedial (AM) and posterolateral (PL) 4-tunnel DB ACL reconstruction with a 5-strand hamstring graft and extracortical fixation were included in a prospective case series. Magnetic resonance imaging scans were performed on the second postoperative day and at 7 months' follow up to assess intraoperative and postoperative bone tunnel enlargement and communication. Tunnel widening was determined in different planes by digitally measuring the diameters of the AM and PL bone tunnels.

RESULTS

Intraoperative communication of the AM bone tunnel with the PL bone tunnel caused by drilling was observed in 23.8% of patients on the tibia and in no case on the femur. At 7 months postoperatively, significant bone tunnel widening occurred at all 4 bone tunnels. It was a mean of 20% for the tibial AM bone tunnel, 38% for the tibial PL bone tunnel, 34% for the femoral AM bone tunnel, and 46% for the femoral PL bone tunnel. Postoperative communication of the AM and PL bone tunnels caused by postoperative bone tunnel widening was observed in 19% of patients on the tibia and femur.

CONCLUSIONS

Intraoperative bone tunnel communication in anatomic DB ACL reconstruction was caused by drilling and occurred only on the tibia. Significant postoperative bone tunnel widening occurred at all 4 bone tunnels and was the highest for the PL bone tunnel. Postoperative bone tunnel communication developed in 19% of patients on the tibia and femur and was caused by bone tunnel widening.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Evaluation of the bone bridge between the bone tunnels after anatomic double-bundle anterior cruciate ligament reconstruction: a multidetector computed tomography study

BACKGROUND

Double-bundle anterior cruciate ligament (ACL) reconstruction is a technically demanding procedure; it requires drilling 2 tibial and 2 femoral tunnels. Tunnel communication, whether intraoperative or postoperative, is a serious complication: It jeopardizes knee stability and graft function.

HYPOTHESIS

During double-bundle ACL reconstruction, special aimers would be helpful to avoid intraoperative bone bridge fracture. The bone bridge between the bone tunnels would maintain its structural integrity, and no tunnel communication would be observed postoperatively because of tunnel widening.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This prospective study included 32 patients undergoing double-bundle ACL reconstruction. A multidetector computed tomography study was performed at a mean of 17 months postoperatively. The thickness of the bone bridge between the bone tunnels was measured in the femoral and tibial sides on an axial and sagittal plane, respectively, at 3 locations: the level of the joint line, the midportion of the bone bridge, and the base of the bone bridge. The bone density of the bone bridge was measured in Hounsfield units in the same locations. Bone density of the anterior tibial cortex and lateral femoral condyle was measured for comparisons.

RESULTS

Tunnel communication occurred intraoperatively in 1 patient on the tibial side at the level of the joint line. In the rest of the patients, a well-defined triangular bone bridge was present between the 2 tunnels in the femoral and tibial sides. The thickness at the apex of the bone bridge was 2.0 and 2.2 mm for the femur and tibia, respectively. In addition, the density of the bone bridge at its apex was similar to that of cortical bone.

CONCLUSION

This study demonstrated that double-bundle ACL reconstruction, as used with anatomic aimers, produces a low rate of tunnel convergence. The bone bridge remains intact postoperatively, although it is thin at the level of the joint line.

Arthroscopic single-bundle anterior cruciate ligament reconstruction with periosteum-enveloping hamstring tendon graft: clinical outcome at 2 to 7 years

PURPOSE

In this case-series outcome study, we present our surgical technique for single-bundle anterior cruciate ligament (ACL) reconstruction with periosteum-enveloping hamstring tendon graft at a minimum of 2 years' follow-up.

METHODS

From 2000 to 2005, ACL reconstruction with a periosteum-enveloping hamstring tendon graft was performed in 368 patients (372 knees). Of those patients, 312 who completed at least 2 years of follow-up were included for analysis. Four-strand periosteum-enveloping hamstring tendon grafts were used for single-bundle reconstruction. Clinical assessments included the Lysholm knee score, International Knee Documentation Committee score, KT-1000 instrumented testing (MEDmetric, San Diego, CA), thigh muscle assessment, and radiographic evaluation. Radiographs were used to assess femoral and tibial tunnel widening.

RESULTS

The 312 study patients were followed up for a mean of 4.6 years (range, 2 to 7 years). The median Lysholm knee scores were 56 points (range, 40 to 70 points) and 95 points (range, 60 to 100 points) before and after surgery, respectively. After reconstruction, 85% of patients could return to moderate or strenuous activity, 5.1% exhibited grade 2 or higher ligament laxity with the anterior drawer test, and 6.1% had a positive pivot shift. Complete range of motion was achieved in 88% of patients. On the basis of International Knee Documentation Committee assessment, 93% of patients had a normal or nearly normal rating.

CONCLUSIONS

Satisfactory results can be achieved with the periosteum-enveloping hamstring tendon graft in single-bundle ACL reconstruction with minimal tunnel widening. Bone tunnel enlargement of more than 1 mm was identified in 5.4% of femoral tunnels and 6.1% of tibial tunnels, which was less than in other studies using comparable fixation.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Biodegradable screw versus a press-fit bone plug fixation for hamstring anterior cruciate ligament reconstruction: a prospective randomized study

BACKGROUND

Press-fit fixation of a tendon graft has been advocated to achieve tendon-to-bone healing.

HYPOTHESIS

Fixation of hamstring tendon grafts with a porous bone scaffold limits bone tunnel enlargement compared with a biodegradable interference screw fixation.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1. Methods Between 2005 and 2006, 20 patients (17 men, 3 women) with a primary reconstruction of the anterior cruciate ligament (ACL) were enrolled in this study. Patients were randomized to obtain graft fixation in the tibial tunnel either by means of an interference screw (I) or a press-fit fixation with a porous bone cylinder (P). At 3 months after surgery, a computed tomography (CT) scan of the knee was performed, and tunnel enlargement was analyzed in the coronal and sagittal planes for the proximal, middle, and distal thirds of the tunnel. After 6 months and 1 and 2 years, radiographs of the knee in the sagittal and coronal plane were analyzed for bone tunnel widening. The International Knee Documentation Committee (IKDC), Tegner, and Lysholm scores of both groups were compared after 1 and 2 years.

RESULTS

The bone tunnel enlargement determined by CT was 106.9% + or - 10.9% for group P and 121.9% + or - 9.0% for group I (P < .02) in the anteroposterior (AP) plane and 102.8% + or - 15.2% versus 121.5% + or - 10.1% in the coronal plane (P <.01). The IKDC, Tegner, and Lysholm scores improved in both groups from preoperatively to postoperatively without significant differences between the 2 groups. There was a trend to higher knee stability in group P after 3 months (0.6 + or - 1.4 mm vs 1.8 + or - 1.5 mm; P = .08).

CONCLUSION

Both interference screw and a press-fit fixation lead to a high number of good or very good outcomes after ACL reconstruction. Tibial press-fit fixation decreases the amount of proximal bone tunnel enlargement.

Tibial tunnel widening after bioresorbable poly-lactide calcium carbonate interference screw usage in ACL reconstruction

Developing bio-absorbable interference screws for anterior cruciate ligament (ACL) reconstruction has proven to be a challenging task. The aim of this study was to investigate the osteogenetic response of poly-lactide carbonate (PLC) interference screws in ACL reconstruction in humans. Ten patients (median age, 28 years) underwent arthroscopic ACL reconstruction with semitendinosus/gracilis tendon graft and a PLC interference screw. The patients were scanned with a multi-slice CT scanner 2 weeks and 1 year postoperatively. Fourteen days postoperatively a mean tunnel widening of 78% [52%; 110%] was observed. At 1-year follow-up, the mean tunnel widening was 128% [84%; 180%]. No sign of bone replacement or bone ingrowth was observed. Factors such as accelerated rehabilitation, micro-motions, and early screw degradation might be responsible for this large tunnel widening. Our results demonstrate the difficulty in translation of preclinical data. This study illustrates the need for extensive preclinical investigation of new materials for clinical purposes.

Anterior cruciate ligament reconstruction: assessment of the hamstring autograft femoral fixation using the EndoButton CL

The objective of this study was to evaluate the clinical and radiological results of a prospective, continuous series of 105 ACL reconstructions using the STG tendons fixed to the femur by an EndoButton CL, with more than 4 years of follow-up.

HYPOTHESIS

The subjective and objective clinical results as well as the radiological results (tunnel enlargement) obtained by a cortical, extra-anatomic femoral fixation are at least equivalent to the results obtained with other types of femoral fixation systems.

MATERIAL AND METHODS

One hundred and five patients aged with a mean 26 years (range, 12-56 years) were operated on for an anterior cruciate ligament rupture using the same technique and by the same operator: four-strand STG fixed to the tibia by a double fixation--BioRCI-HA screw and staple--and on the femur by an EndoButton CL (Smith and Nephew). The results were assessed at 6 months, 1 and 2 years and then at a mean follow-up of 51 months, both clinically (IKDC, Lysholm, KT-1000) and radiologically (Telos laximetry, tunnel position, and morphological analysis).

RESULTS

No complications related to the use of the EndoButton were observed. No additional interference screw was necessary. According to the IKDC laxity classification, 91.4% of the patients were classified in category A or B, nine knees (8.6%) were classified C or D. Four failures required revision with a patellar tendon graft. On the final IKDC score, 63 patients (60%) were classified grade A, 37 grade B (35.3%), four grade C (3.8%), and one grade D (0.9%). On the Telos laximetry, 62 patients (59%) had a differential laxity less than or equal to 2 mm. The mean value was 1.8 mm (range, 0-11). Tibial tunnel enlargement was constant; femoral tunnel enlargement was significant (>2 mm) in 27.6% of the knees. No femoral tunnel diameter modification corresponding to the EndoButton passage was observed.

DISCUSSION

The results of this series are comparable to the results of other series. Its reproducibility and the absence of iatrogenic complications for this femoral EndoButton CL fixation make it a top-choice technique, like the corticocancellous graft procedures, but without their disadvantages. No secondary elongation attributable to the EndoButton CL was observed. This femoral fixation procedure appeared necessary and sufficient to providing good mechanical stability for the graft in the femoral tunnel.

Differences in tendon graft healing between the intra-articular and extra-articular ends of a bone tunnel

The basic biology of healing between a tendon graft and bone tunnel remains incompletely understood. Distinct variability in the morphological characteristics of the healing tendon-bone attachment site has been reported. We hypothesized that spatial and temporal differences in tendon-to-bone healing exist at different regions of a surgically created bone tunnel. Twenty-four male, Sprague-Dawley rats underwent anterior cruciate ligament (ACL) reconstruction in the left knee using a flexor digitorum longus tendon graft secured using suspensory periosteal fixation. Animals were sacrificed at 4, 7, 11, 14, 21, and 28 days after surgery and prepared for routine histology and immunohistochemical analysis of the healing enthesis at the intra-articular aperture (IAA), mid-tunnel, and extra-articular aperture (EAA). Six animals were used to measure mineral apposition rate (MAR) along the healing bone tunnel by double fluorochrome labeling at 14 and 28 days after surgery. The total area of calcified bone matrix was assessed with von Kossa staining and Goldner-Masson trichrome staining, respectively. The healing tendon-bone interface tissue exhibited a wide chondroid matrix at the IAA, in contrast to a narrow, fibrous matrix at the EAA. There were significantly more osteoclasts at the IAA compared to EAA throughout the study period, except 4 days after surgery (p < 0.05). Collagen continuity between the tendon graft and bone tunnel increased over time, with a more parallel orientation and increased collagen fiber continuity between tendon and bone at the EAA compared to the IAA. MAR was also significantly greater at the EAA at 4 weeks (p < 0.001). Significant differences in healing between the tendon graft and bone exist along the length of bone tunnel secured with suspensory fixation. The etiology of these differences is likely multifactorial in nature, including variable biological and biomechanical environments at different ends of the tunnel. Understanding these differences may ultimately allow surgeons to improve the quality of graft fixation and long-term outcomes after ACL reconstruction.

Tunnel widening following anterior cruciate ligament reconstruction using hamstring autograft: a comparison between double cross-pin and suspensory graft fixation

Femoral and tibial tunnel widening following ACL reconstruction using hamstring autograft has been described. Greater tunnel widening has been reported with suspensory fixation systems. We hypothesized that greater tunnel widening will be observed in patients whose hamstring autograft was fixated using a cortical, suspensory system, compared to double cross-pin fixation on the femur. We performed clinical and radiographic evaluation on 46 patients at minimum 2 years after primary ACL reconstruction. We measured subjective and objective outcomes including KT-1000 and AP, lateral radiographs. A musculoskeletal radiologist, independent of the surgical team, measured tunnel width, while correcting for magnification, at the widest point and at 1 cm away from tibial and femoral tunnel apertures. Patients in the suspensory graft fixation group exhibited significantly greater absolute change and greater percent change in femoral tunnel diameter compared to patients with double cross-pin fixation (P<or=0.05). This difference was noted on both AP and lateral radiographs and at both measurement sites. There was no significant difference between groups for tibial tunnel widening, IKDC subjective scores or KT-1000 side to side differences. There was significantly more femoral tunnel widening associated with the use of the endobutton suspensory fixation system compared to the use of double cross-pins for fixation within the tunnel.

Tunnel enlargement after anterior cruciate ligament reconstruction in patients with post-operative septic arthritis

Tunnel enlargement is a frequent issue after ACL reconstruction and the "synovial bathing effect" is thought to be among the biological factors contributing to this phenomenon. Since the amount and the pressure of the synovial fluid inside the knee joint are higher and the length of its presence is longer in patients with post-operative septic arthritis after ACL reconstruction, we reviewed the tunnel enlargement in these cases in order to better evaluate this phenomenon in such a hostile environment. The null hypothesis of this study was that the highly represented phenomenon of the "synovial bathing effect" that occurs in an infected ACL reconstruction would not affect the amount of post-operative tunnel widening. A case-control study was done. At a mean follow up of 10 months (range 9-11 months) eight patients with septic arthritis following ACL reconstruction (group A) were radiologically reviewed using a CT scan and the diameters of femoral and tibial tunnels were measured. The results were compared with a control group (B) of uncomplicated ACL reconstruction cases operated by the same surgeon using the same technique. Although patients of Group A experienced a bigger amount of tunnel enlargement than patients of group B both on femoral (9.53 +/- 1.07 vs. 9.35 +/- 1.52 mm) and tibial side (10.07 +/- 1.3 vs. 9.92 +/- 0.74 mm), no clinical or statistically significant differences were detected between the groups (P > 0.05). No significant tunnel enlargement could be detected in patients of group A when compared with patients of group B. This seems to minimize the role of biological factors contributing to tunnel widening.

Femoral seating position of the EndoButton in single incision anterior cruciate ligament reconstruction: an anatomical study

Arthroscopic EndoButton fixation of anterior cruciate ligament (ACL) grafts over the femoral cortex has become popular in recent years. However, elongation of fixation materials has lead to tunnel enlargement, graft tunnel motion and instability. Synovial fluid passages along femoral tunnels following ACL reconstruction may result in destruction of tissues. The purpose of the present study was to identify the seating position of the EndoButton in regard to the boundaries of the knee capsule in single-incision arthroscopic ACL reconstruction. A total of 20 cadaveric knees were dissected and arthroscopic drill guides were used to create tibial and femoral tunnels. The distances between the exit points and boundaries of the suprapatellar bursa at three different degrees of knee flexion were measured. The average distances from the exit points to the superior boundaries of the suprapatellar bursa were 6.89 +/- 5.40 mm (range, 16.87-1.21). However, in knee flexion of greater than 90 degrees , tunnel exits were placed below the superior boundaries of the suprapatellar bursa (-7.08 +/- 3.69 mm, range, -3.24 to -12.87). In order to place the EndoButton extraarticularly, a safe degree of knee flexion during femoral tunnel drilling was defined as 80 degrees .

Anterior cruciate ligament reconstruction graft harvesting: pitfalls and tips

Surgical treatment for anterior cruciate ligament deficiency has relied predominantly on reconstruction with autografts. Grafts taken from patients' own central third of their patellar tendon, bone-patellar tendon bone, or one or more of the hamstring tendons, semitendinosus, and gracilis, constitute the majority of grafts used for these purposes. Although there is no single graft option that clearly outperforms another, an abundance of articles replete with complications associated with harvest and use are available from peer-reviewed journals. It is these complications and their prevention that will be addressed in the following chapter. The idea in mind is that the reader might adopt these techniques to improve their patient outcomes by minimizing, or eliminating, the ongoing problems that such complications produce.

Biology of autograft and allograft healing in anterior cruciate ligament reconstruction

The graft-bone attachment site is the weak link in anterior cruciate ligament (ACL) reconstruction surgery because healing is slow and often incomplete. Each of the many graft options for ACL reconstruction surgery has different healing characteristics and potential. Autografts that allow bone-to-bone healing offer the best healing potential. An understanding of the biology of graft healing should give the surgeon context in graft selection and rehabilitation for ACL reconstruction.

Early versus late start of open kinetic chain quadriceps exercises after ACL reconstruction with patellar tendon or hamstring grafts: a prospective randomized outcome study

The purpose of the present investigation was to evaluate physical outcome after anterior cruciate ligament (ACL) reconstruction with early versus late initiation of open kinetic chain (OKC) exercises for the quadriceps in patients operated on either patellar tendon or hamstring grafts. Sixty-eight patients, 36 males and 32 females, with either patellar tendon graft (34 patients) or hamstring graft (34 patients) were enrolled in this study. All patients were randomly allocated to either early (the 4th postoperative week) or late (the 12th postoperative week) start of OKC exercises for the quadriceps, resulting in four subgroups: patellar tendon reconstruction, early start (P4) or late start (P12) of OKC quadriceps exercises, hamstring tendon reconstruction, early start (H4) or late start (H12) of quadriceps OKC exercises. Prior to surgery and 3, 5 and 7 months later, assessments of range of motion (goniometer), anterior knee laxity (KT-1000), postural sway (KAT 2000), thigh muscle torques (Kin-Com dynamometer) and anterior knee pain (anterior knee pain score) were evaluated. No significant group differences were found in terms of range of motion 3, 5 and 7 months postoperatively. The H4 group showed a significantly higher mean difference of laxity over time of 1.0 mm (CI: 0.18-1.86) than the P4 group (P=0.04). Within the same type of surgery, the H4 against the H12, the mean difference over time was 1.2 mm (0.37-2.1) higher in the H4 group than in the H12 group (P=0.01). There were no significant group differences in terms of postural sway or anterior knee pain at the different test occasions. Significant differences in trends (changes over time) were found when comparing the four groups, for both quadriceps muscle torques (P<0.001) and hamstring muscle torques (P<0.001). All groups, except the P4 group, reached preoperative values of quadriceps muscle torques at the 7 months follow-up. In the H4 and the H12 groups, significantly lower hamstring muscle torques at the 7 months follow-up compared with preoperative values were found. In conclusion, early start of OKC quadriceps exercises after hamstring ACL reconstruction resulted in significantly increased anterior knee laxity in comparison with both late start and with early and late start after bone-patellar tendon-bone ACL reconstruction. Furthermore, the early introduction of OKC exercises for quadriceps did not influence quadriceps muscle torques neither in patients operated on patellar tendon nor hamstring tendon grafts. On the contrary, it appears as if the choice of graft affected the strength of the specific muscle more than the type of exercises performed. Our results could not determine the appropriate time for starting OKC quadriceps exercises for patients who have undergone ACL reconstruction with hamstring tendon graft. Future studies of long-term results of anterior knee laxity and functional outcome are needed.

The effect of accelerated, brace free, rehabilitation on bone tunnel enlargement after ACL reconstruction using hamstring tendons: a CT study

The mechanism of bone tunnel enlargement following anterior cruciate ligament (ACL) reconstruction is not yet clearly understood. Many authors hypothesized that aggressive rehabilitation protocols may be a potential factor for bone tunnel enlargement, especially in reconstructions performed with hamstrings autograft. The purpose of this study was to evaluate the effect of a brace free rehabilitation on the tunnel enlargement after ACL reconstruction using doubled semitendinosus and gracilis tendons (DGST): our hypothesis was that early post-operative knee motion increase the diameters of the tibial and femoral bone tunnels. Forty-five consecutive patients undergoing ACL reconstruction for chronic ACL deficiency were selected. All patients were operated by the same surgeon using autologous DGST and the same fixation devices. Patients with associated ligaments injuries and or severe chondral damage were excluded. The patients were randomly assigned to enter the control group (group A, standard post-operative rehabilitation) and the study group (group B, brace free accelerated rehabilitation). A CT scan was used to exactly determine the diameters of both femoral and tibial tunnels at various levels of lateral femoral condyle and proximal tibia, using a previously described method [17]. Measurements were done by an independent radiologist in a blinded fashion the day after the operation and at a mean follow-up of 10 months (range 9-11). Statistical analysis was performed using paired t-test. The mean femoral tunnel diameter increased significantly from 9.04 +/- 0.05 (post-operative) to 9.30 +/- 0.8 mm (follow-up) in group A and from 9.04 +/- 0.03 to 9.94 +/- 1.12 mm in group B. The mean tibial tunnel diameter increased significantly from 9.03 +/- 0.04 to 10.01 +/- 0.80 mm in group A and from 9.04 +/- 0.03 to 10.60 +/- 0.78 mm in group B. The increase in femoral and tunnel diameters observed in the study group was significantly higher than that observed in the control group. Our results suggest that bone tunnel enlargement after ACL reconstruction using hamstrings autograft can be increased by an accelerated, brace free, rehabilitation protocol.

A new device for the fixation of anterior cruciate ligament tendon grafts

In this paper the design and experimental analysis is presented of a new fixation device of anterior cruciate ligament (ACL) grafts of the knee. This device is inserted into the bone tunnel, after the graft, in the same way as an interference screw. However, the fixation device described in this paper has been designed in such a way that, after the insertion of a threaded element in its interior, some of its components expand in a radial direction, pressing against the walls of the bone tunnel and thereby increasing the fixation of the graft. This expansion device can be used in both the femur and the tibia. The device proposed in this paper was compared with an interference screw for load failure and fixation stiffness in experiments performed using porcine bones. The failure load was significantly higher in the new expansion device group (633+/-202 N) than in the interference screw group (471+/-179 N). The stiffness obtained when the new device was used (59+/-20 N/mm) was also significantly higher than that obtained using the interference screw (37+/-19 N/mm) (t-test, P<0.05). According to these results, this new device could be considered a good alternative to improve fixation of anterior cruciate ligament grafts.

A prospective study of 3-day versus 2-week immobilization period after anterior cruciate ligament reconstruction

BACKGROUND

Aggressive early rehabilitation is recommended after reconstruction of the anterior cruciate ligament (ACL) using a patellar tendon-bone graft. However, rehabilitation after reconstruction of ACL using the multistranded hamstring is controversial. In this study, we compared the clinical results of 3-day immobilization after reconstruction of ACL using the multistranded hamstring, with those of 2-week immobilization prospectively.

METHODS

A total of 30 consecutive patients with ruptured ACL underwent single-socket ACL reconstruction. 10 male and 5 female patients (mean age of 29.2+/-10.0 years) were prospectively randomized for a 3-day immobilization period, and 6 male and 9 female patients (mean age of 27.3+/-10.9 years) were randomized for a 2-week immobilization period. We measured the anterior laxity with a KT-2000 arthrometer, joint position sense, and thigh muscle strength at 3, 6 and 12 months after surgery.

RESULTS AND CONCLUSIONS

There were no statistically significant differences between the two groups. We concluded that the post-operative 3-day immobilization period is preferable to the longer 2-week period in our rehabilitation program from the viewpoint of psychological load to the patients and the duration of hospitalization after ACL reconstruction using multistranded hamstring tendons.

Tendon healing in a bone tunnel differs at the tunnel entrance versus the tunnel exit: an effect of graft-tunnel motion?

BACKGROUND

Motion between a tendon graft and bone tunnel may impair graft incorporation and lead to tunnel widening.

HYPOTHESIS

Healing of a tendon graft in a bone tunnel is inhibited by graft-tunnel motion.

STUDY DESIGN

Controlled laboratory study.

METHODS

Anterior cruciate ligament reconstruction was performed in 5 cadaveric rabbit limbs, and 3-dimensional graft-tunnel motion was measured using micro-computed tomography. The authors then performed bilateral anterior cruciate ligament reconstruction in 15 rabbits and used histomorphometry to compare tendon-to-bone healing between the tunnel aperture, midtunnel, and tunnel exit and between the anterior and posterior aspects of the tunnel.

RESULTS

Graft-tunnel motion was greatest at the tunnel apertures and least at the tunnel exit in cadaveric testing. Healing of the graft was slowest at the tunnel apertures. Tendon-bone interface width was greater at the aperture than at the tunnel exit for the femoral tunnel (P = .04). There was an inverse correlation between time zero graft-tunnel motion and healing in the femoral tunnel (P = .005). There was closer apposition of new bone to the tendon graft in the posterior half of the interface (P < .05). Osteoclasts were found at the tunnel apertures.

CONCLUSION

Although graft-tunnel motion was only measured in cadaveric animals, results suggest that healing may be affected by the local mechanical environment, as graft healing in the femoral tunnel was inversely proportional to the magnitude of graft-tunnel motion.

CLINICAL RELEVANCE

Graft-tunnel motion may impair early graft incorporation and may lead to osteoclast-mediated bone resorption, contributing to tunnel widening. Early, aggressive postoperative rehabilitation may have detrimental effects on graft-to-bone healing.

Biodegradable and metallic interference screws in anterior cruciate ligament reconstruction surgery using hamstring tendon grafts: prospective randomized study of radiographic results and clinical outcome

BACKGROUND

The use of biodegradable screws in anterior cruciate ligament reconstruction has grown in popularity.

PURPOSE

To compare the clinical and radiographic results in arthroscopically assisted anterior cruciate ligament reconstruction using 4-strand hamstring tendon grafts and either metallic (metal group) or biodegradable (PLLA group) interference screw fixation.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A randomized series of 77 patients, all with a unilateral anterior cruciate ligament rupture, was included in the study. The preoperative assessments in both groups were similar in gender, Tegner activity level, Lysholm score, KT-1000 arthrometer measurements, and single-legged hop test results. In both groups, interference screw fixation of the graft was used at both ends, and 68 of 77 (88%) patients returned for a radiographic examination at 6 and 24 months, respectively.

RESULTS

At follow-up, no significant differences were found between the 2 groups in KT-1000 arthrometer laxity measurements, Tegner activity level, or Lysholm score. The PLLA group had a significantly better outcome in the single-legged hop test and the final International Knee Documentation Committee classification (P = .007 and P = .03, respectively). At 6 and 24 months after the index operation, the PLLA group displayed significantly larger drill holes on the radiographs than did the metal group on both the tibial (8.1 vs 6.6 mm at 6 months [P = .0007]; 6.0 vs 3.2 mm at 24 months [P < .0001]) and femoral sides (7.8 vs 5.6 mm at 6 months [P < .0001]; 6.3 vs 1.9 mm at 24 months [P < .0001]).

CONCLUSION

There were significantly larger radiographically visible drill holes on both the tibial and femoral sides in the PLLA group compared with the metal group at 6 and 24 months. Clinical examination at 2 years revealed no major differences between the groups. The larger drill holes in the PLLA group did not correlate with inferior clinical results.

Tunnel expansion after anterior cruciate ligament reconstruction with autogenous hamstrings: a comparison of the medial portal and transtibial techniques

PURPOSE

The purpose of this study was to evaluate the effects of 2 techniques of drilling the femoral tunnel in anterior cruciate ligament (ACL) reconstruction (medial portal v transtibial) on tunnel expansion.

METHODS

Autogenous hamstring ACL reconstructions performed by the senior author between July 1998 and July 2004, with a minimum 6-month radiographic follow-up, using the transtibial technique (41 patients) and the medial portal technique (34 patients), were evaluated. All procedures were performed via an endoscopic technique with identical postoperative rehabilitation and graft fixation. Lateral and 45 degrees posteroanterior (PA) radiographs were obtained for each patient at a minimum of 6 months postoperatively. The sclerotic margins of the femoral and tibial tunnels were measured at the widest dimension of the tunnel by 2 physicians and were compared with the initially drilled tunnel size after correction for radiographic magnification. Statistical analysis was performed to compare the 2 groups by use of the independent-samples t test, with significance set at .05.

RESULTS

The mean percentage increase in the femoral tunnel was 38.20% +/- 17.76% for the medial portal technique and 53.96% +/- 21.72% for the transtibial technique on the PA view and 23.80% +/- 16.50% for the medial portal technique and 50.07% +/- 26.98% for the transtibial technique on the lateral view. This difference was statistically significant on both PA and lateral views. The mean percentage increase in the tibial tunnel was 31.81% +/- 14.39% for the medial portal technique and 36.31% +/- 17.81% for the transtibial technique on the PA view and 27.70% +/- 15.25% for the medial portal technique and 30.11% +/- 18.98% for the transtibial technique on the lateral view; however, these increases failed to reach statistical significance on either view.

CONCLUSIONS

Femoral tunnel expansion for hamstring autologous ACL reconstructions is significantly lower for the medial portal technique when compared with the conventional transtibial technique.

LEVEL OF EVIDENCE

Level III, retrospective, comparative therapeutic study.

Time-related changes in the cross-sectional area of the tibial tunnel after compaction of an autograft bone dowel alongside a hamstring graft

PURPOSE

Extensive tunnel expansion in hamstring anterior cruciate ligament (ACL) reconstruction can complicate revision surgery. The purpose of this study was to examine our hypothesis that compaction of a bone dowel into the tibial tunnel reduces the cross-sectional area of the tunnel on the day of surgery and limits tunnel expansion to that of the cross-sectional area of the reamer at 4 months and 1 to 2 years.

METHODS

A bone dowel averaging 23 mm in length and 7 mm in diameter was harvested from the tibial tunnel in 10 patients undergoing hamstring ACL reconstruction. The tibial tunnel was dilated, and the bone dowel was compacted anterior to the tendon graft. The cross-sectional area of the tibial tunnel was calculated on the day of surgery and at 4 months and 1 to 2 years postoperatively from computed tomography scans.

RESULTS

On the day of surgery, the cross-sectional area of the tibial tunnel was 34% smaller than the 50-mm2 cross-sectional area of the 8-mm reamer used to drill the tunnel (P < .001). At 1 to 2 years, the cross-sectional area of the tibial tunnel was smaller than that of the reamer in 6 subjects, was slightly larger (53 to 56 mm2) in 3 subjects, and was substantially larger (80 mm2) in 1 subject.

CONCLUSIONS

A surgeon who compacts an autogenous bone dowel into the tibial tunnel alongside a hamstring graft can expect little to no tunnel expansion in 90% of patients at 1 to 2 years. To our knowledge, the limitation of tunnel expansion to that of the cross-sectional area of the reamer has not been shown with other tibial fixation techniques.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Bone tunnel enlargement after ACL reconstruction using autologous hamstring tendons: a CT study

PURPOSE

To evaluate prospectively the increase in the size of the tibial and femoral bone tunnel following arthroscopic anterior cruciate ligament (ACL) reconstruction with quadrupled-hamstring autograft.

METHODS

Twenty-five consecutive patients underwent arthroscopic ACL reconstruction with quadrupled-hamstring autograft. Preoperative clinical evaluation was performed using the Lysholm knee score, Tegner activity level, and International Knee Documentation Committee forms and a KT-1000 arthrometer (side to side). Computed tomography (CT) of the femoral and tibial tunnel was performed on the day after operation in all cases and at mean follow-up of 10 months (range 9-11 months).

RESULTS

All of the clinical evaluation scales performed showed an overall improvement. The postoperative anterior laxity difference was <3 mm in 16 patients (70%) and 3-5 mm in seven patients (30%). The mean average femoral tunnel diameter increased significantly (3%) from 9.04+/-0.05 mm postoperatively to 9.3+/-0.8 mm at 10 months; tibial tunnel increased significantly (11%) from 9.03+/-0.04 mm to 10+/-0.8 mm. There were no statistically significant differences between tunnel enlargement, clinical results, and arthrometer evaluation.

CONCLUSIONS

The rate of tunnel widening observed in this study seems to be lower than that reported in previous studies that used different techniques. We conclude that an anatomical surgical technique and a less aggressive rehabilitation process influenced the amount of tunnel enlargement after ACL reconstruction with doubled hamstrings.