Comparison of resorption and remodeling of bioabsorbable interference screws in anterior cruciate ligament reconstruction

Biphasic Scaffold Loaded With Autologous Cartilage Yields Better Clinical Outcome and Magnetic Resonance Imaging Filling Compared With Marrow Stimulation for Focal Osteochondral Lesions in the Knee

PURPOSE

To evaluate the effectiveness of marrow stimulation (MS) versus biphasic scaffold loaded with autologous cartilage (scaffold) in treating focal osteochondral lesions of the knee.

METHODS

In total, 54 patients with symptomatic focal chondral or osteochondral lesion in the knee were randomized to either the scaffold group or the MS group. International Knee Documentation Committee subjective score, the Knee Injury Osteoarthritis Outcome Score, and magnetic resonance imaging (MRI) were assessed preoperatively and at 1 and 2 years after operation to compare treatment outcomes. Biopsy and second-look arthroscopy were performed at 1 year postoperatively for consenting patients.

RESULTS

There were 27 patients (mean age 31.33 ± 10.95 years) in the scaffold group, and 27 patients (31.74 ± 11.44) in the MS group. The scaffold group and the MS group both included 23 patients with lesions ≤12.5 × 12.5 mm2 mm in size. In addition, each group had 4 patients with lesions between than 12.5 × 12.5 mm2 and ≤12.5 × 25 mm2. Both interventions achieved significant improvement in clinical outcome scores at 2 years. The scaffold group had greater International Knee Documentation Committee score than the MS group at 2 years (93.85 ± 9.55 vs 92.11 ± 9.84) and in the Symptoms/Stiffness and Sport/Recreation subscales of Knee Injury Osteoarthritis Outcome Score at 2 years (96.57 ± 5.97 vs 93.57 ± 6.52, P < .05) and (90.2 ± 17.76 vs 82.8 ± 16.08, P < .05).

CONCLUSIONS

The use of biphasic scaffold loaded with autologous cartilage in treating focal osteochondral lesions demonstrates superior clinical outcomes and better cartilage refill on magnetic resonance imaging at the 2-year follow-up compared to marrow stimulation.

LEVEL OF EVIDENCE

Level I, Randomized controlled trial.

Sheathed fixation improves BASHTI technique in an anterior cruciate ligament reconstruction

Bone and Site Hold Tendon Inside (BASHTI) technique is an implant-less surgical methodology used for anterior cruciate ligament (ACL) reconstruction. It has some clinical advantages, such as speeding up the healing process. Since the force required to insert the core bone inside the tunnel may damage the core bone and affect the fixation process, the study aims to investigate the strength of fixation of BASHTI technique using proposed sheathed core bones. Experimental tests were performed to evaluate the biomechanical strength of the fixation. Synthetic bone combined with bovine tendons as a graft was used. Polymers were used to create the sheath for mechanical testing. The results showed that fixation strength and stiffness in PTFE sheath with 0.1 mm were 343.86 N and 114.62 N/mm and in PVC sheath with similar thickness, 235.95 N, and 93.36 N/mm. Subsequently, 0.2 mm PTFE sheaths were tested in two different sections: incomplete fixation and complete fixation. The strength and stiffness of the first section were 221.6 N and 66.99 N/mm and for the second section 420.02 N and 126.16 N/mm. Using sheath facilitates the fixation process in BASHTI technique. The 0.1 mm PTFE sheath and 0.2 mm PTFE sheath with complete fixation provide higher fixation strength than other groups. The outcome showed that engaged length has a direct effect on the fixation strength. The BASHTI technique offers an implant-less organic ACL reconstruction method that can improve the fixation method and speed up the healing process.

Biomaterials Used for Suture Anchors in Orthopedic Surgery

Suture anchors are broadly used for attaching soft tissue (e.g., tendons, ligaments, and meniscus) to the bone and have become essential devices in sports medicine and during arthroscopic surgery. As the usage of suture anchors has increased, various material-specific advantages and challenges have been reported. As a result, suture anchors are continually changing to become safer and more efficient. In this ever-changing environment, it is clinically essential for the surgeon to understand the key characteristics of existing anchors sufficiently. This paper aims to summarize the current concepts on the characteristics of available suture anchors.

Biocomposite Interference Screws in Anterior Cruciate Ligament Reconstruction: Osteoconductivity and Degradation

Purpose

To evaluate the long-term in vivo degradation of an amorphous stereoisomer combined with micro β-tricalcium phosphate poly levo (96%)/dextro (4%) lactide beta-tricalcium phosphate biocomposite interference screw.

Methods

A study approved by the institutional review board of in vivo biologic behavior of the screw was initiated in 2011 using an anterior cruciate ligament (ACL) reconstruction model. Twenty patients undergoing bone–patellar tendon–bone ACL reconstruction fixed at the femur and tibia with these biocomposite screws followed at least 36 months were evaluated by physical, radiographic, and computed tomography (CT) evaluations. Lysholm, Tegner, Cincinnati, and International Knee Documentation Committee scores were obtained. CT Hounsfield unit (HU) data were obtained at the femoral and tibial screw and other bone sites. An ossification quality score (range 1-4) was used to determine osteoconductivity at the screw sites.

Results

In total, 11 male and 9 female patients evaluated by CT scan and radiographs a mean of 41 months postsurgery (range, 37-51) showed bone plug healing to the tunnel wall and the screw replaced with calcified and nontrabecular material. Osteoconductivity was present in 34 of 40 tunnels (85%) and nearly complete or complete (type 3 or 4 ossification) in 10 of 40 (25%). Mean screw-site densities (femoral 239 HU; tibial 290 HU) were consistent with cancellous bone density. One positive pivot-shift test was found. Lysholm, Cincinnati, Tegner, and International Knee Documentation Committee activity scores improved from 46.9, 43.5, 1.9, and 1.7 preoperatively to 92, 90.2, 6.0, and 3.2 at follow-up, respectively. The average postoperative Single Assessment Numeric Evaluation score was 86 and mean KT-1000 arthrometer difference was 0.32 mm.

Conclusions

The micro β-tricalcium phosphate poly levo (96%)/dextro (4%) lactide beta-tricalcium phosphate interference screw was replaced by calcified, nontrabecular material a mean of 42 months after implantation in a bone–patellar tendon–bone ACL reconstruction model. Osteoconductivity was confirmed.

Level of Evidence

Level IV (therapeutic case series).

The five year outcome of a clinical feasibility study using a biphasic construct with minced autologous cartilage to repair osteochondral defects in the knee

PURPOSE

Autologous minced cartilage has been used to repair cartilage defects. We have developed a biphasic cylindrical osteochondral construct for such use in human knees, and report the five year post-operative outcomes.

METHODS

Ten patients with symptomatic osteochondral lesion at femoral condyles were treated by replacing pathological tissue with the osteochondral composites, each consisted a _DL-poly-lactide-co-glycolide chondral phase and a _DL-poly-lactide-co-glycolide/β-tricalcium phosphate osseous phase. A flat chamber between the two phases served as a reservoir to house double-minced (mechanical pulverization and enzymatical dissociation) autologous cartilage graft. The osteochondral lesion was drill-fashioned a pit of identical dimensions as the construct. Graft-laden construct was press fit to the pit. Post-operative outcome was evaluated using Knee Injury and Osteoarthritis Outcome Score (KOOS) up to five years. Regenerated tissue was sampled with arthroscopic needle biopsy for histology at one year, and imaged with magnetic resonance at one, three, and five years to evaluate the neocartilage with MOCART chart. Subchondral bone integration was evaluated with computed tomography at three and five years.

RESULTS

Nine patients completed the five-year follow-up. Post-operative mean KOOS, except that of the "symptom" subscale, had been significantly higher than pre-operation from one year and maintained to five years. The change of MOCRAT scores of the regenerated cartilage paralleled the change of KOOS. The osseous phase remained mineralized during the five-year period, yet did not fully integrate with the host bone.

CONCLUSIONS

This novel construct for chondrocyte implantation yielded promising mid-term outcome. It repaired the osteochondral lesion with hyaline-like cartilage durable for at least five years.

Bioabsorbable screws, whatever the composition, can result in symptomatic intra-osseous tibial tunnel cysts after ACL reconstruction

PURPOSE

To describe the clinical results of patients who underwent surgical treatment for a intra-osseous tibial tunnel cyst on a bioabsorbable interference screw following anterior cruciate ligament reconstruction (ACL).

METHODS

This retrospective study included all patients who underwent surgery between 2004 and 2016 for an intra-osseous tibial tunnel cyst on bioabsorbable interference screw following ACL reconstruction. The diagnosis was suggested clinically by pretibial pain at the incision site, sometimes associated with a palpable subcutaneous nodule and then confirmed on MRI. The first stage of surgery included exploratory arthroscopy followed by open excision/curettage of the cyst and then the tunnel was filled. The main criterion for outcome was a clinically normal knee (no pain, 0-120 range of motion, stable, with no effusion) at 6 months of follow-up.

RESULTS

This series included 53 patients, mean age 35.3 ± 9.9 years old w ith a mean 4.6 ± 3.1 years (between 3.1 months and 19 years) of follow-up after ligament reconstruction. The tibial screw was completely absorbed in 9/53 (17%) of patients, and fragmented in 22/53 (41.5%). At the 6-month follow-up, 42/53 (79.2%) patients had a normal knee, 11/53 (20.8%) persistent pain in the cyst area, 52/53 (98.1%) normal range of motion and 53 (100%) a stable knee. A recurrent cyst developed at 2 years of follow-up in one patient.

CONCLUSION

Complete absorption of a bioabsorbable interference screw is long, increasing the risk of developing intra-osseous tibial cysts during this period. The development of new materials with improved absorption properties is needed.

LEVEL OF EVIDENCE

IV-Retrospective study.

A new bioabsorbable polymer film to prevent peritoneal adhesions validated in a post-surgical animal model

Background

Peritoneal adhesions are a serious surgical postoperative complication. The aim of this study is to investigate, in a rat model, the anti-adhesive effects of a bioabsorbable film of polymer combining polyethylene glycol and polylactic acid.

Materials and methods

Sixty-three animals were randomized into five groups according to the anti-adhesion treatment: Hyalobarrier^®, Seprafilm^®, Polymer A (PA), Polymer B (PB), and control. The rats were euthanized on days 5 and 12 to evaluate the extent, severity and degree of adhesions and histopathological changes. Three animals were euthanized at day 2 in PA, PB and control groups to observe the in vivo elimination.

Results

Macroscopic adhesion formation was significantly lower in the PA group than in the control group at day 5 (median adhesion score 0±0 vs 9.6 ±0.5 p = 0.002) and at day 12 (0±0 vs 7.3±4 p = 0.02). Furthermore, median adhesion score at day 5 was significantly lower in the PA group than in the Seprafilm group (0±0 vs 4.2± 3.9 p = 0.03). Residence time of PA seems longer than PB.

Conclusion

The PA bioabsorbable film seems efficient in preventing the formation of peritoneal adhesions.

Clinical and Functional Outcomes of Anterior Cruciate Ligament Reconstruction at a Minimum of 2 Years Using Adjustable Suspensory Fixation in Both the Femur and Tibia: A Prospective Study

Background:

The success of anterior cruciate ligament (ACL) reconstruction requires reliable and rigid graft fixation. Cortical suspensory fixation (CSF) devices have become an acceptable alternative to interference screws for soft tissue ACL grafts. However, CSF devices have been reported to be associated with tunnel widening and increased postoperative anterior laxity compared with interference screw fixation. Adjustable CSF devices were introduced to avoid these problems but have been associated with graft lengthening and inconsistent outcomes.

Purpose:

To (1) report the side-to-side difference (SSD) in anterior laxity at 150 N, clinical scores, and failure rates 2 years after ACL reconstruction with 4-strand semitendinosus autografts using an adjustable CSF device and (2) determine the preoperative factors associated with clinical outcomes.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

A total of 131 patients who had undergone primary ACL reconstruction, performed with 4-strand semitendinosus grafts that were secured using Pullup adjustable-length CSF devices with femoral and tibial fixation techniques, were prospectively enrolled in this study; 34 patients were excluded because of contralateral instability or ipsilateral knee injuries that required additional surgery. This left a cohort of 97 patients who were evaluated preoperatively and at 6, 12, and 24 months. The evaluation consisted of measuring the SSD in anterior laxity and patient-reported outcome scores (International Knee Documentation Committee [IKDC] and Lysholm scores). Regression analyses were performed to determine associations between these outcomes and 9 preoperative variables.

Results:

Only 2 patients could not be reached, 2 could not be evaluated because of contralateral ACL tears, and 2 had graft failure. At 2-year follow-up, the remaining 91 patients had a mean SSD in anterior laxity of 0.8 ± 1.8 mm (range, –4.2 to 5.3 mm), mean IKDC score of 87.6 ± 10.6 (range, 43.7-100.0), and mean Lysholm score of 90.8 ± 9.3 (range, 56.0-100.0). At final follow-up, compared with knees with partial ruptures, those with complete ruptures had equivalent laxity (P = .266) and Lysholm scores (P = .352) but lower IKDC scores (P = .009). Multivariable regression revealed that the IKDC score decreased with increased preoperative laxity (β = –1.35 [95% CI, –2.48 to –0.23]; P = .019).

Conclusion:

The novel adjustable-length CSF device produced satisfactory anterior laxity and clinical outcomes, with a failure rate of 2.1%, which compare favorably with those reported for nonadjustable CSF devices.

Radiographic Tibial Tunnel Assessment After Anterior Cruciate Ligament Reconstruction Using Hamstring Tendon Autografts and Biocomposite Screws: A Prospective Study With 5-Year Follow-Up

PURPOSE

To radiographically assess the tibial tunnel up to 5 years after anterior cruciate ligament (ACL) reconstruction using hamstring tendon autografts and biocomposite interference screws.

METHODS

Fifty-one patients underwent anatomic single-bundle ACL reconstruction with metal interference screws in the femur and biocomposite interference screws in the tibia. Standardized digital radiographs with weight-bearing anteroposterior and lateral views of the index knee were taken in the early postoperative period and at 2 and 5 years postoperatively. Of 51 patients, 40 (78%) underwent radiographic assessment on all 3 occasions. Subjective and objective clinical assessments were obtained preoperatively and at the 5-year follow-up.

RESULTS

The mean follow-up period was 65 months (±3.9 months), with a minimum of 59 months. The width of the tibial tunnel on the anteroposterior view was 9.4 mm (±1.4 mm) in the early postoperative period and 9.2 mm (±1.5 mm) at 5 years (P = .64). The corresponding widths on the lateral view were 9.6 mm (±1.5 mm) in the early postoperative period and 9.0 mm (±1.4 mm) at 5 years (P = .014). In 33 of 40 patients (83%) the width of the tibial tunnel had decreased on 1 or both views at 5 years compared with the early postoperative period. The study group had improved significantly at the 5-year follow-up compared with the preoperative assessments in terms of the KT-1000 arthrometer laxity tests (MEDmetric, San Diego, CA), pivot-shift test, Tegner activity scale, and Lysholm knee score (P < .001). No correlations were found between the tunnel widths and the KT-1000 assessment.

CONCLUSIONS

In 83% of patients, the width of the tibial tunnel had decreased on 1 or both radiographic views at 5 years compared with the early postoperative period after ACL reconstruction using biocomposite interference screws.

LEVEL OF EVIDENCE

Level II, prospective study.

Tunnel widening after ACL reconstruction with aperture screw fixation or all-inside reconstruction with suspensory cortical button fixation: Volumetric measurements on CT and MRI scans

BACKGROUND

Tunnel widening after anterior cruciate ligament reconstruction (ACLR) is influenced by the surgical and fixation techniques used. Computed tomography (CT) is the most accurate image modality for assessing tunnel widening, but magnetic resonance imaging (MRI) might also be reliable for tunnel volume measurements. In the present study tunnel widening after ACLR using biodegradable interference screw fixation was compared with all-inside ACLR using button fixation, with tunnel volume changes being measured on CT and MRI scans.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

Thirty-three patients were randomly assigned to hamstring ACLR using a biodegradable interference screw or all-inside cortical button fixation. CT and MRI scanning were done at the time of surgery and six months after. Tunnel volume changes were calculated and compared.

RESULTS

On CT, femoral tunnel volumes changed from the postoperative state (100%) to 119.8% with screw fixation and 143.2% with button fixation (P=0.023). The changes in tibial tunnel volumes were not significant (113.9% vs. 117.7%). The changes in bone tunnel volume measured on MRI were comparable with those on CT only for tunnels with interference screws. Tibial tunnels with button fixation were significantly underestimated on MRI scanning (P=0.018).

CONCLUSIONS

All-inside ACLR using cortical button fixation results in increased femoral tunnel widening in comparison with ACLR with biodegradable interference screw fixation. MRI represents a reliable imaging modality for future studies investigating tunnel widening with interference screw fixation.

Resorbable screw and sheath versus resorbable interference screw and staples for ACL reconstruction: a comparison of two tibial fixation methods

PURPOSE

The anterior cruciate ligament (ACL) reconstruction is one of the most performed and successful orthopaedic procedures. The results are considered independent by the choice of the graft and the fixation devices. A growing interest on resorbable non-metallic fixation devices versus standard metallic fixation devices has been noted over recent years with few clinical experiences reported in the literature. The aim of this study is to compare the clinical and radiological outcomes of patients undergoing ACL reconstruction using autologous hamstring tendons with tibial fixation by a centrally placed resorbable screw and sheath to a combination of an eccentrically placed resorbable interference screw and supplementary staple fixation.

METHODS

Ninety patients undergoing an isolated, single-bundle, primary ACL reconstruction with autologous hamstring tendons, using the same femoral fixation, were randomized to a tibial fixation with a centrally placed resorbable screw and sheath, BioIntrafix (group A), or an eccentrically placed resorbable interference screw, BioRCI, and two non-resorbable staples (group B). The latter has represented for many years our standard fixation method. Clinical evaluations (KOOS, IKDC, KT-2000™ side-to-side difference) and radiological analyses were conducted in both groups with a minimum follow-up of 2 years.

RESULTS

We assisted in a satisfactory pain relief and functional improvements, without significant clinical and radiological differences in both groups. No further surgery was needed in patients with the screw/sheath tibial fixation. Seven patients with the screw/staples tibial fixation needed the surgical removal of the fixation devices due to pes anserinus irritation or local infection years after the index operation. Other parameters such as the tunnel enlargement were not statistically different in the two groups.

CONCLUSIONS

Good clinical and radiological outcomes of ACL reconstruction by a screw/sheath tibial fixation have been reported showing comparable results with respect to screw/staples fixation. There were no failures associated with loss of fixation with either of tibial fixation methods. A fewer number of surgical removals of tibial devices were also recorded in patients treated by the screw/sheath fixation system, related to the absence of local intolerance or infection compared to subjects with a standard tibial fixation.

Biocomposite Implants Composed of Poly(Lactide-co-Glycolide)/β-Tricalcium Phosphate: Systematic Review of Imaging, Complication, and Performance Outcomes

PURPOSE

To determine the degradation and performance outcomes of poly(lactide-co-glycolide)/β-tricalcium phosphate (PLGA/β-TCP) implants.

METHODS

A MEDLINE and Embase search for randomized or nonrandomized controlled studies and prospective or retrospective case series that used biocomposite interference screws or suture anchors composed of PLGA/β-TCP was performed. Main outcomes included volume of implant resorption and incidence of osteoconductivity at implant sites, imaging findings, adverse events, and the frequency of reoperations.

RESULTS

A total of 13 studies representing 668 patients with either knee or shoulder implants were included. Median follow-up was 28 months (range: 12-37 months). Biocomposite implants lost 88% of their original volume during follow-up. Osteoconductivity at the implant site was identified in 63% of cases. Adverse events included tunnel widening (3%), effusion (5%), and cyst formation (4%). Synovitis was not reported.

CONCLUSIONS

Biocomposite interference screws or suture anchors composed of PLGA/β-TCP almost fully absorb over 3 years while promoting osteoconductivity with few reported adverse events.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

Femoral and Tibial Tunnel Diameter and Bioabsorbable Screw Findings After Double-Bundle ACL Reconstruction in 5-Year Clinical and MRI Follow-up

Background:

Tunnel enlargement is frequently seen in short-term follow-up after anterior cruciate ligament reconstruction (ACLR). According to new evidence, tunnel enlargement may be followed by tunnel narrowing, but the long-term evolution of the tunnels is currently unknown.

Hypothesis/Purpose:

The hypothesis was that tunnel enlargement is followed by tunnel narrowing caused by ossification as seen in follow-up using magnetic resonance imaging (MRI). The purpose of this study was to evaluate the ossification pattern of the tunnels, the communication of the 2 femoral and 2 tibial tunnels, and screw absorption findings in MRI.

Study Design:

Case series; Level of evidence, 4.

Methods:

Thirty-one patients underwent anatomic double-bundle ACLR with hamstring grafts and bioabsorbable interference screw fixation and were followed with MRI and clinical evaluation at 2 and 5 years postoperatively.

Results:

The mean tunnel enlargement at 2 years was 58% and reduced to 46% at 5 years. Tunnel ossification resulted in evenly narrowed tunnels in 44%, in conical tunnels in 48%, and fully ossified tunnels in 8%. Tunnel communication increased from 13% to 23% in the femur and from 19% to 23% in the tibia between 2 and 5 years and was not associated with knee laxity. At 5 years, 54% of the screws were not visible, with 35% of the screws replaced by a cyst and 19% fully ossified. Tunnel cysts were not associated with worse patient-reported outcomes or knee laxity. Patients with a tibial anteromedial tunnel cyst had higher Lysholm scores than patients without a cyst (93 and 84, P = .03).

Conclusion:

Tunnel enlargement was followed by tunnel narrowing in 5-year follow-up after double-bundle ACLR. Tunnel communication and tunnel cysts were frequent MRI findings and not associated with adverse clinical evaluation results.

Incorporation of Hamstring Grafts Within the Tibial Tunnel After Anterior Cruciate Ligament Reconstruction: Magnetic Resonance Imaging of Suspensory Fixation Versus Interference Screws

BACKGROUND

The success of anterior cruciate ligament (ACL) reconstruction requires solid graft incorporation within the tunnels to enable graft remodeling. Resorbable interference screws (RIS) provide limited tendon-bone contact because much of the tunnel circumference is occupied by the screw itself, while adjustable suspensory fixation (ASF) systems provide larger contact zones, which favor ligamentization.

PURPOSE

To evaluate ligamentization of a 4-strand semitendinosus (4ST) graft fixed with ASF compared with RIS within the tibial bone tunnel at 6 months postoperatively using magnetic resonance imaging (MRI).

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

We prospectively enrolled 121 consecutive patients undergoing primary ACL reconstruction using a single-bundle 4ST graft. The femoral end of the graft was fixed using suspensory fixation in all knees. The tibial end of the graft was fixed using ASF in 67 knees and RIS in 54 knees. Six months postoperatively, knee laxity measurements were taken, and MRI was performed to assess graft incorporation within the tibial tunnel.

RESULTS

At 6-month follow-up, MRI scans of 109 knees were available for analysis. The mean tibial tunnel enlargement in the ASF group was 2.3 ± 1.1 mm (range, 0.5-6.0 mm), while in the RIS group, it was 4.7 ± 2.8 mm (range, 0.5-19.0 mm) (P < .001). The Howell graft signal assessment findings were excellent in 97% of knees in the ASF group and in 25% of knees in the RIS group (P < .001). The mean signal-to-noise quotient (SNQ) was 0.078 ± 0.62 in the ASF group and 0.671 ± 0.83 in the RIS group (P < .001).

CONCLUSION

ASF provides more favorable conditions than RIS for the incorporation and ligamentization of 4ST grafts within the tibial tunnel. The ASF system used showed very little tunnel widening, which suggests that it grants stabilization. The SNQ was also considerably better in the ASF group.

Efficacy of Osteoconductive Ceramics in Bioresorbable Screws for Anterior Cruciate Ligament Reconstruction: A Prospective Intrapatient Comparative Study

Background:

Osteoconductive additives are used in resorbable interference screws for anterior cruciate ligament (ACL) reconstruction to improve graft incorporation and mitigate adverse effects. There are no published studies that compare biological performances of bioresorbable and biocomposite screws without artifacts due to different follow-up times and intrinsic patient characteristics.

Purpose/Hypothesis:

The purpose of this study was to evaluate the efficacy of osteoconductive agents in bioresorbable screws for ACL reconstruction at minimum follow-up of 2 years by intrapatient comparison. The hypothesis was that osteoconductive ceramics would result in slower resorption, improved ossification, and less tunnel widening.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

A total of 28 ACL reconstructions at 2 centers were randomly assigned into 2 comparable groups: (1) the graft was fixed in the tibia using standard bioresorbable screws and in the femur using biocomposite screws with osteoconductive agents (biphasic calcium phosphate), and (2) the graft was fixed in the femur using a standard bioresorbable screw and in the tibia using a biocomposite screw with osteoconductive agents.

Results:

Twenty-seven patients completed evaluations at 29.9 ± 4.0 months. Resorption was complete for more bioresorbable (81%) than biocomposite (37%) screws (P = .0029), whereas satisfactory ossification was observed in more biocomposite (52%) than bioresorbable (15%) screws (P = .0216). The tunnel shape was normal in more biocomposite (81%) than bioresorbable (48%) screws (P = .0126), and marked cortical formation was twice more frequent for biocomposite (78%) than bioresorbable (37%) screws (P = .0012). Bioresorbable screws exhibited faster resorption in the femur (P = .0202) but not in the tibia (not significant). Conversely, biocomposite screws demonstrated better ossification, less tunnel widening, and more cortical formation in the tibia (P < .0001, P = .0227, and P < .0001, respectively) but not in the femur (not significant for all).

Conclusion:

Osteoconductive additives can reduce the extent of resorption while improving ossification, reducing tunnel widening, and increasing cortical formation.

Clinical Relevance:

The benefits of osteoconductive agents justify their associated costs for ACL reconstruction, particularly in the tibia.

Long-Term Degradation of Self-Reinforced Poly-Levo (96%)/Dextro (4%)-Lactide/β-Tricalcium Phosphate Biocomposite Interference Screws

PURPOSE

To evaluate the long-term in vivo degradation of biocomposite interference screws made with self-reinforced poly-levo (96%)/dextro (4%)-lactide/β-tricalcium phosphate [SR-PL(96)/D(4)LA/β-TCP].

METHODS

A study of the in vivo biologic behavior of an SR-PL(96)/D(4)LA/β-TCP biocomposite interference screw was initiated in 2011 using an anterior cruciate ligament (ACL) reconstruction model. Eight patients undergoing a bone-patellar tendon-bone ACL reconstruction fixed at both the femur and tibia with an SR-PL(96)/D(4)LA/β-TCP screw at least 36 months earlier were evaluated by physical, radiographic, and computed tomography (CT) evaluations. Lysholm, Tegner, Cincinnati, and International Knee Documentation Committee scores were obtained. After incomplete degradation was observed in these 8 patients, a subsequent series of 17 patients were evaluated at a minimum of 48 months after surgery. By use of CT scans, Hounsfield unit (HU) data were obtained at the femoral and tibial screw and other bone sites. An ossification quality score (range, 1 to 4) was used to determine osteoconductivity at the screw sites.

RESULTS

Eleven male and 6 female patients evaluated by CT scan and radiographs at a mean of 50 months (range, 48 to 61 months) after surgery showed bone plug healing to the tunnel wall and the SR-PL(96)/D(4)LA/β-TCP screws were replaced with material that was calcified and non-trabecular. Osteoconductivity was present in 24 of 34 tunnels (70.58%) and nearly complete or complete (type 3 or 4 ossification) in 11 of 34 (32.35%). Mean screw site densities (femoral, 242 HU; tibial, 240 HU) were consistent with cancellous bone density. One positive pivot-shift test was found. Lysholm, Cincinnati, Tegner, and International Knee Documentation Committee activity scores improved from 44.5, 40.7, 2.3, and 1.4, respectively, preoperatively to 92, 92.4, 5.7, and 3.3, respectively, at follow-up (P < .0001). The average postoperative Single Assessment Numeric Evaluation score was 92. The mean KT arthrometer (MEDmetric, San Diego, CA) difference was 1.25 mm.

CONCLUSIONS

The SR-PL(96)/D(4)LA/β-TCP interference screw was replaced with calcified, non-trabecular material 4 years after implantation in a bone-patellar tendon-bone ACL reconstruction model. Osteoconductivity was confirmed in 24 of 34 screw sites (71%), with nearly complete or complete filling in 11 of 34 (33%). The SR-PL(96)/D(4)LA/β-TCP biocomposite interference screw is osteoconductive.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Distal biceps tendon repair: comparison of clinical and radiological outcome between bioabsorbable and nonabsorbable screws

BACKGROUND

Distal biceps tendon repair to the radial tuberosity can be conducted by means of an interference screw in combination with a transosseous button. Bioabsorbable interference screws have been associated with complications such as severe osteolytic reactions. We questioned whether patients with a distal biceps tendon repair with bioabsorbable poly-L-lactide (PLLA) screws had different functional, clinical, and radiologic outcome than patients with nonabsorbable poly-ether ether ketone (PEEK) screws.

METHODS

Between 2010 and 2014, 23 patients with an acute distal biceps tendon rupture were treated with reinsertion of the distal biceps tendon in a bone tunnel at the radial tuberosity through a single anterior incision using a transosseous button combined with an interference screw. A PLLA screw was used in 12 patients and a PEEK screw in 11 patients. All patients were retrospectively evaluated with a minimal follow-up of 1 year clinically and by means of the visual analog scale for pain, Mayo Elbow Performance Score, and Disabilities of Arm, Shoulder and Hand Outcome Measure score. Bone tunnel volume was measured with computed tomography segmentation.

RESULTS

Elbow mobility and arm and forearm circumference were symmetric for all patients. The visual analog scale for pain was 0.2 in the PLLA group and 0.7 in the PEEK group. The Disabilities of Arm, Shoulder and Hand score and Mayo Elbow Performance Score were 5.4 and 98.7 in the PLLA group vs. 3.1 and 95.9 in the PEEK group. Bone tunnel enlargement of 43% in the PLLA and 38% in the PEEK group was noted.

CONCLUSIONS

Clinical and functional outcome at more than 1 year after distal biceps tendon repair was excellent in both groups. Bone tunnel widening occurred in all patients.

Cortical femoral suspensory fixation using screw post in anatomic single-bundle anterior cruciate ligament reconstruction: a prospective study and mid-term outcome results

PURPOSE

Cortical femoral suspensory fixation using screw post in ACLR has the advantage of allowing complete filling of the femoral tunnel with graft tissue. In addition, the low cost of the implants is an advantage in countries where cost is an issue of concern. The purpose of the current study was to evaluate the clinical functional outcome results of cortical femoral suspensory fixation using screw post at mid-term follow-up.

METHODS

Single surgeon single centre prospective case series study. Sixty two patients having complete ACL tears were included in the current study. Average follow-up was 52.6 months (range 38-68). Objective and subjective IKDC scores, Lysholm knee score, SF-36 score, VAS for patients' satisfaction, VAS for pain and Kellgren & Lawrence (K/L) classification of osteoarthritis were used for follow-up evaluation.

RESULTS

Objective IKDC score revealed that 59 patients had grade "A" and 3 had grade "B", while no single patient had neither grade "C" nor "D". The average Lysholm score was 90.7, average subjective IKDC was 89.5. Average SF-36 score was 94.8. The average VAS for operation satisfaction was 9.4. Average VAS for pain was 0.2. Forty six patients were classified as normal K/L classification, nine were grade "1", seven were grade "2". Comparing pre-operative and follow-up objective IKDC, subjective IKDC, Lysholm, SF-36, and VAS for pain scores revealed statistically significant differences (P-value <0.05).

CONCLUSION

Femoral suspensory fixation using screw post in ACLR showed excellent functional outcome results at mid-term follow-up.

Perianchor Cyst Formation Around Biocomposite Biodegradable Suture Anchors After Rotator Cuff Repair

BACKGROUND

Biodegradable anchors may lead to perianchor cyst formation or osteolysis. A new generation of anchors containing osteoconductive material was recently presented, but there is currently no solid evidence that this concept decreases cyst formation around anchors.

HYPOTHESIS

The null hypothesis was that the prevalence and severity of cyst formation around anchors would be similar for all 3 anchor types.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

To evaluate differences between anchor behaviors postoperatively, this study included 2 groups of patients who underwent rotator cuff repair. In group 1 (n = 38), transosseous-equivalent rotator cuff repair was performed in all patients. At the time of repair, 2 different anchors (anchor A: 23% microstructured β-tricalcium phosphate plus 77% polylactic acid enantiomers [PLLA]; and anchor B: 30% hydroxyapatite plus 70% PLLA) were used for medial-row repair. Insertion locations (anterior or posterior) were randomly assigned. In group 2 (n = 38), the same procedure was performed; however, 1 of the anchors used in group 1 was changed (anchor A: as above; and anchor C: 30% β-tricalcium phosphate plus 70% faster absorbing polylactic-co-glycolic acid copolymer [85% PLLA plus 15% polyglycolic acid]). The presence and severity of fluid collection around the anchors was evaluated by magnetic resonance imaging at approximately 1 year after rotator cuff repair (12.7 ± 0.9 months for group 1 and 12.6 ± 1.8 months for group 2).

RESULTS

In group 1, a fluid signal was observed in 14 patients (36.8%) for anchor A and in 12 patients (31.6%) for anchor B (P > .05). The severity of perianchor cyst formation was no different for the 2 anchors (respective fluid signal grades [0-4]: 24, 3, 9, 1, and 1 for anchor A; and 26, 4, 7, 1, and 0 for anchor B; P > .05). However, in group 2, cysts were observed in 19 patients (50%) for anchor A and in 3 patients (7.9%) for anchor C (P < .001). For anchor C, only 2 cases of grade 1 and 1 case of grade 2 fluid collection were observed. Intergroup analysis of anchor A revealed no significant differences in the prevalence or severity of perianchor cyst formation (P > .05). Healing failure was observed in 12 patients (31.6%) in group 1 and 10 patients (26.3%) in group 2 (P > .05).

CONCLUSION

New-generation biodegradable suture anchors seem to decrease the severity of perianchor cyst formation. Future research is required to optimize the compositions and proportions of osteoconductive materials and polymers to improve adverse reactions. Nevertheless, controlling the properties of polymers and adding osteoconductive material both appear to enhance biocompatibility.