Primary ligament sutures as a treatment option of knee dislocations: a meta-analysis

Purpose

Treatment of knee dislocation is still controversial. There is no evidence to favour ligament suture or reconstruction. Until now, no meta-analyses have examined suture versus reconstruction of cruciate ligaments in knee dislocations with respect to injury pattern and rupture classification.

Methods

We searched Medline, the Cochrane Controlled Trial Database, and EMBASE for studies on surgical treatment for ‘knee dislocation’ and ‘multiple ligament injured knee’. A meta-analysis was performed using individual patient data.

Results

Nine studies including 195 patients (200 knees) with a mean age of 31.4 (±13) years fulfilled the study requirements. Thirteen cases of type II dislocations, 63 cases of type III medial, 84 cases of type III lateral, and 40 cases of type IV dislocations, according to Schenck’s classification, were found. Poor or moderate results were found in 70 % of patients without surgical treatment of ACL or PCL (n = 27). Patients (n = 40) treated by sutures of the ACL and PCL demonstrated a significantly greater proportion of excellent or good results (40 and 37.5 %, respectively) (p < 0.001). Patients who underwent reconstruction of the ACL and PCL (n = 75) showed excellent or good results (28 and 45 %, respectively). No significant difference was found when comparing suture versus reconstruction of the ACL and PCL (n.s.). The outcome depends considerably on Schenck’s injury pattern classification.

Conclusion

Conservative treatment after knee dislocation yields poor clinical results. Suture repair of cruciate ligaments can still serve as an alternative option for multiligament injuries of the knee and achieve good clinical results, which are comparable to those of ligament reconstruction. The data provided by this meta-analysis should be reinforced by a prospective study, in which suture repair and ligament reconstruction are compared.

Level of evidence

IV.     

Comparison of double-bundle anterior cruciate ligament (ACL) reconstruction and single-bundle reconstruction with remnant pull-out suture

Purpose

The purpose of this study was to evaluate the stability and functional outcomes of anterior cruciate ligament (ACL) reconstruction by tensioning of the ACL remnant using pull-out sutures compared with ACL double-bundle reconstruction.

Methods

Forty-four patients were included in single-bundle reconstruction with remnant tensioning group (Group 1), and 56 patients were included in the double-bundle reconstruction group (Group 2). The remnant tissue was tensioned to the direction of posterolateral bundle, which unrelated to the type of remnant bundle. Objective knee stability was evaluated by anterior stress radiography, KT-1000 and lateral pivot shift tests. The Tegner activity scale, International Knee Documentation Committee and OrthopädischeArbeitsgruppeKnie scoring systems were used for clinical evaluation.

Results

No statistically significant intergroup differences were observed in mechanical stability and clinical results (n.s). However, surgical time of remnant tensioning group is shorter than double-bundle reconstruction group (P = 0.005).

Conclusion

Remnant tensioning suture with single-bundle reconstruction could be used with positive results as good as double-bundle technique if a good ACL remnant was found bridging the femur and tibia, rather than debride or damage to the remnant tissue during operation.

Level of evidence

Retrospective, comparative cohort study, Level IV.     

Cartilage repair using mesenchymal stem cell (MSC) sheet and MSCs-loaded bilayer PLGA scaffold in a rabbit model

Purpose

The integration of regenerated cartilage with surrounding native cartilage is a major challenge for the success of cartilage tissue-engineering strategies. The purpose of this study is to investigate whether incorporation of the power of mesenchymal stem cell (MSC) sheet to MSCs-loaded bilayer poly-(lactic-co-glycolic acid) (PLGA) scaffolds can improve the integration and repair of cartilage defects in a rabbit model.

Methods

Rabbit bone marrow-derived MSCs were cultured and formed cell sheet. Full-thickness cylindrical osteochondral defects (4 mm in diameter, 3 mm in depth) were created in the patellar groove of 18 New Zealand white rabbits and the osteochondral defects were treated with PLGA scaffold (n = 6), PLGA/MSCs (n = 6) or MSC sheet-encapsulated PLGA/MSCs (n = 6). After 6 and 12 weeks, the integration and tissue response were evaluated histologically.

Results

The MSC sheet-encapsulated PLGA/MCSs group showed significantly more amounts of hyaline cartilage and higher histological scores than PLGA/MSCs group and PLGA group (P < 0.05). In addition, the MSC sheet-encapsulated PLGA/MCSs group showed the best integration between the repaired cartilage and surrounding normal cartilage and subchondral bone compared to other two groups.

Conclusions

The novel method of incorporation of MSC sheet to PLGA/MCSs could enhance the ability of cartilage regeneration and integration between repair cartilage and the surrounding cartilage. Transplantation of autologous MSC sheet combined with traditional strategies or cartilage debris might provide therapeutic opportunities for improving cartilage regeneration and integration in humans.     

Collagen application reduces complication rates of mid-substance ACL tears treated with dynamic intraligamentary stabilization

Purpose

Dynamic intraligamentary stabilization was recently proposed as an option for the treatment of acute ACL ruptures. The aim of this study was to investigate the feasibility of the procedure in mid-substance ACL ruptures and examine whether the additional application of a bilayer collagen I/III membrane would provide for a superior outcome.

Methods

The study group consisted of patients presenting with a mid-substance ACL rupture undergoing dynamic intraligamentary stabilization using the Ligamys? device along with application of a collagen I/III membrane to the surface of the ACL (group A, n = 23). The control group comprised a matched series of patients presenting with a mid-substance ACL rupture also treated by dynamic intraligamentary stabilization Ligamys? repair, however, without additional collagen application (group B, n = 33). Patients were evaluated preoperatively and at 24-month follow-up for stability as well as Tegner and Lysholm scores. Knee laxity was measured as a difference in anterior translation (ΔAP) and pivot shift. Any events occurring during the follow-up period of 24 months were documented. Logistic regression of complications was performed, and adjustment undertaken where necessary.

Results

A high total complication rate of 78.8 % was noted in group B, compared to group A (8.7 %) (p = 0.002). The addition of a collagen membrane was the only independent prognostic factor associated with reduced complications (OR 8.0, CI 2.0–32.2, p = 0.003, for collagen-free treatment). In group B, 6 patients suffered a re-rupture with subsequent instability requiring secondary hamstring reconstruction surgery, and 11 developed extension loss requiring arthroscopic debridement, whilst in group A, 2 patients required arthroscopic debridement for loss of exension, with no further encountered complication. Median Lysholm score was significantly higher in group A compared to group B (median 100 range 93–100 vs median 95 range 60–100, p = 0.03) at final follow-up.

Conclusions

A high complication rate following ACL Ligamys? repair of mid-substance ruptures was noted. Application of a collagen membrane to the surface of the ACL resulted in a reduced incidence of extension deficit and re-ruptures. The results indicate that solitary ACL Ligamys? repair does not present an appropriate treatment modality for mid-substance ACL ruptures. Collage application proved to provide healing benefits with superior clinical outcome after ACL repair.

Level of evidence

Case control study, Level III.

     

Adhesion and collagen production of human tenocytes seeded on degradable poly(urethane urea)

Purpose

The aim of this study was to investigate whether human tenocytes taken from ruptured quadriceps tendon could be seeded on a biodegradable polycaprolactone-based polyurethanes (PU) urea scaffold. Scaffold colonization and collagen production after different culture periods were analyzed to understand whether tenocytes from ruptured tendons are able to colonize these biodegradable scaffolds.

Methods

Human primary tenocyte cultures of ruptured quadriceps tendons were seeded on PU scaffolds. After 3, 10 and 15 days of incubation, the samples were stained with haematoxylin and eosin and were examined under white light microscopy. After 15 and 30 days of incubation, samples were examined under transmission electron microscope. Total collagen accumulation was also evaluated after 15, 30 and 45 days of culture.

Results

After 15 and 30 days of culture, tenocyte-seeded scaffolds showed cell colonization and cell accumulation around interconnecting micropores. Tenocyte phenotype was variable. Collagen accumulation in seeded scaffolds demonstrated a progressive increase after 15, 30 and 45 days of culture, while control non-seeded scaffolds show no collagen accumulation.

Conclusion

These results showed that human tenocytes from ruptured quadriceps tendon can be seeded on polycaprolactone-based PU urea scaffolds and cultured for a long time period (45 days). This study also showed that human tenocytes from ruptured tendons seeded on PU scaffolds are able to penetrate the scaffold showing a progressively higher collagen accumulation after 15, 30 and 45 days of incubation. This study provides the basis to use this PU biodegradable scaffold in vivo as an augmentation for chronic tendon ruptures and in vitro as a scaffold for tissue engineering construct.     

Potential of healing a transected anterior cruciate ligament with genetically modified extracellular matrix bioscaffolds in a goat model

Purpose

Biological augmentation to heal a torn anterior cruciate ligament (ACL) has gained significant interest. This study examined the potential advantages of using extracellular matrix (ECM) bioscaffolds from galactosyl-α(1,3)galactose deficient pigs to heal the transected ACL.

Methods

In 16 skeletally mature goats, the ACL in the right hindlimb was transected and repaired. In 9 of these animals, an ECM sheet was wrapped around the injury site and with an ECM hydrogel injected into the transected site. The remaining 7 animals were treated with suture repair only. The left hindlimb served as a sham-operated control.

Results

After 12?weeks, the healing ACL in the ECM-treated group showed an abundance of continuous neo-tissue formation, while only limited tissue growth was found after suture repair only. The cross-sectional area of the ACL from the ECM-treated group was similar to sham-operated controls (n.s.) and was 4.5?times those of the suture repair group (P?P?P?Conclusions The application of an ECM bioscaffold and hydrogel was found to accelerate the healing of a transected ACL following suture repair in the goat model with limited tissue hypertrophy and improvement in some of its biomechanical properties. Although more work is necessary to fully restore the function of the normal ACL, these early results offer a potential new approach to aid ACL healing.     

Comparison of Achilles and tibialis anterior tendon allografts after anterior cruciate ligament reconstruction

Purpose

The purpose of this study was to compare the outcomes after anterior cruciate ligament (ACL) reconstruction using Achilles tendon allografts and tibialis anterior (TA) tendon allografts with respect to objective knee testing measures, second-look arthroscopy and femoral tunnel enlargement.

Methods

A total of 131 patients who underwent ACL reconstruction between 2000 and 2006 were retrospectively reviewed. Achilles tendon allografts were used in 81 patients (group I). These patients were compared with 50 patients in whom TA tendon allografts were used (group II). The two groups were assessed using International Knee Documentation Committee (IKDC), Lysholm and Tegner activity scores, as well as KT-2000 testing. Second-look arthroscopic findings were evaluated. Cross-sectional area (CSA) perpendicular to the long axis of the femoral tunnel was also calculated digitally using magnetic resonance imaging.

Results

No significant differences were observed between the two groups with respect to IKDC, Lysholm or Tegner activity scores or the results of laxity testing with arthrometry. Synovial coverage of more than 50 % was found in 71.1 % cases in group I and 75 % cases in group II. Mean CSA enlargement of 15 % (group I) and 38 % (group II) was detected (p = 0.017).

Conclusions

The clinical results associated with Achilles and TA tendons were not significantly different. The laxity evaluation and second-look arthroscopy demonstrated no significant differences between group I and group II. However, Achilles tendon-bone plugs for femoral tunnel fixation reduced femoral tunnel enlargement compared to the TA allograft. Achilles tendon allografts for ACL reconstruction could be a reasonable option in selected patients.

Level of evidence

Retrospective case series, Level IV.     

Osteochondral regeneration using a novel aragonite-hyaluronate bi-phasic scaffold in a goat model

Purpose

The objective of this study was to examine whether different mechanical modifications and/or impregnation of hyaluronic acid (HA) might enhance aragonite-based scaffold properties for the regeneration of cartilage and bone in an animal model.

Methods

Bi-phasic osteochondral scaffolds were prepared using coralline aragonite with different modifications, including 1- to 2-mm-deep drilled channels in the cartilage phase (Group 1, n = 7) or in the bone phase (Group 2, n = 8), and compared with unmodified coral cylinders (Group 3, n = 8) as well as empty control defects (Group 4, n = 4). In each group, four of the implants were impregnated with HA to the cartilage phase. Osteochondral defects (6 mm diameter, 8 mm depth) were made in medial and lateral femoral condyles of 14 goats, and the scaffolds were implanted according to a randomization chart. After 6 months, cartilage and bone regeneration were evaluated macroscopically and histologically by an external laboratory.

Results

Group 1 implants were replaced by newly formed hyaline cartilage and subchondral bone (combined histological evaluation according to the ICRS II-2010 and O’Driscoll et al. 34 ± 4 n = 7). In this group, the cartilaginous repair tissue showed a smooth contour and was well integrated into the adjacent native cartilage, with morphological evidence of hyaline cartilage as confirmed by the marked presence of proteoglycans, a marked grade of collagen type II and the absence of collagen type I. The average scores in other groups were significantly lower (Group 2 (n = 8) 28.8 ± 11, Group 3 (n = 8) 23 ± 9 and Group 4 (empty control, n = 4) 19.7 ± 15).

Conclusions

The implants with the mechanical modification and HA impregnation in the cartilage phase outperformed all other types of implant. Although native coral is an excellent material for bone repair, as a stand-alone material implant, it does not regenerate hyaline cartilage. Mechanical modification with drilled channels and impregnation of HA within the coral pores enhanced the scaffold’s cartilage regenerative potential. The modified implant shows young hyaline cartilage regeneration. This implant might be useful for the treatment of both chondral and osteochondral defects in humans.     

Anatomic single- versus double-bundle ACL reconstruction: a meta-analysis

Purpose

To determine whether anatomic double-bundle anterior cruciate ligament (ACL) reconstruction compared to anatomic single-bundle ACL reconstruction more effectively restored antero–posterior (A–P) laxity, rotatory laxity and reduced frequency of graft rupture. Our hypothesis was that anatomic double-bundle ACL reconstruction results in superior rotational knee laxity and fewer graft ruptures due to its double-bundle tension pattern, compared with anatomic single-bundle ACL reconstruction.

Methods

An electronic search was performed using the PubMed, EMBASE and Cochrane Library databases. All therapeutic trials written in English reporting knee kinematic outcomes and graft rupture rates of primary anatomic double- versus single-bundle ACL reconstruction were included. Only clinical studies of levels I–II evidence were included. Data regarding kinematic tests were extracted and included pivot-shift test, Lachman test, anterior drawer test, KT-1000 measurements, A–P laxity measures using navigation and total internal–external (IRER) laxity measured using navigation, as well as graft failure frequency.

Results

A total of 7,154 studies were identified of which 15 papers (8 randomized controlled trials and 7 prospective cohort studies, n = 970 patients) met the eligibility criteria. Anatomic ACL double-bundle reconstruction demonstrated less anterior laxity using KT-1000 arthrometer with a standard mean difference (SMD) = 0.36 (95 % CI 0.214–0.513, p < 0.001) and less A–P laxity measured with navigation (SMD = 0.29 95 % CI 0.01–0.565, p = 0.042). Anatomic double-bundle ACL reconstruction did not lead to significant improvements in pivot-shift test, Lachman test, anterior drawer test, total IRER or graft failure rates compared to anatomic single-bundle ACL reconstruction.

Conclusion

Anatomic double-bundle ACL reconstruction is superior to anatomic single-bundle reconstruction in terms of restoration of knee kinematics, primarily A–P laxity. Whether these improvements of laxity result in long-term improvement of clinical meaningful outcomes remains uncertain.

Level of evidence

II.     

Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft

Purpose

The aim was to compare the outcome of anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone (BPTB) autograft, with and without a poly(urethane urea) augmentation device.

Methods

Patients were randomized to BPTB reconstruction with a synthetic degradable augmentation device (n = 96) or without augmentation (n = 105). Follow-ups were made during 4 years after surgical treatment with the KT1000? arthrometer for objective evaluation of sagittal stability. The Tegner scoring system for assessment of physical activity level and the Knee injury Osteoarthritis Outcome Score (KOOS) for assessment of knee-specific health were evaluated after 4 and 12 years.

Results

KT1000? tests showed a significant decrease in mean manual maximum side-to-side difference after 4 years in both patients with and those without augmentation, without any statistical difference between the groups (n.s.). Pre-injury, 76 and 80 % of the patients, respectively, reported Tegner level 7–10. Pre-surgery, the corresponding figures were 6 and 5 %, and at 4 years, 33 and 30 %. Twelve years after ACL reconstruction, both groups had significantly higher KOOS scores in function in sports and recreational activities (p < 0.001) and knee-related quality of life (p < 0.001) compared to before surgical treatment. In 10 patients, the augmentation device was removed, in six of these because of insufficient screw fixation to femur and in four due to swelling/hydrops.

Conclusion

This study showed no significant difference in clinical outcome with use of an additional synthetic augmentation device in a single-bundle BPTB ACL reconstruction compared with non-augmentation, in short, intermediate, or long-term perspective.

Level of evidence

Therapeutic study, Level I.     

Comparison of femoral tunnel length between transportal and retrograde reaming outside-in techniques in anterior cruciate ligament reconstruction

Purpose

To evaluate the accuracy of intraoperative femoral tunnel length measurement and to compare this between the transportal (TP) and outside-in (OI) techniques for double-bundle (DB) anterior cruciate ligament (ACL) reconstruction.

Methods

Eighty patients underwent a DB ACL reconstruction using either the TP or the OI technique. The participants were randomized to either a TP group (I, 40 cases) or a OI group (II, 40 cases). The intraoperatively measured femoral tunnel length was recorded, and the postoperative femoral tunnel length was measured using computed tomography with OsiriX^® imaging software.

Results

The mean femoral tunnel lengths measured intraoperatively in Group II (38.9 ± 3.0 mm for anteromedial [AM], 39.3 ± 3.4 mm for posterolateral [PL]) were significantly longer than those of Group I (34.8 ± 2.7 mm for AM, 36.0 ± 3.2 mm for PL) (P < 0.001). The mean AM femoral tunnel length measured postoperatively in Group II (33.3 ± 3.8 mm) was significantly longer than that in Group I (31.1 ± 2.9 mm) (P = 0.006). The mean intraoperatively measured femoral tunnel length was significantly longer than that measured postoperatively in Groups I and II (P < 0.001).

Conclusion

After anatomic DB ACL reconstruction, the femoral tunnel length of the OI technique measured intraoperatively (AM/PL) and postoperatively (AM) was longer than those of the TP technique. The femoral tunnel length measured intraoperatively was longer than that measured postoperatively in both TP and OI technique. This study may help surgeons to measure femoral tunnel length accurately in anatomic DB ACL reconstruction with suspensory fixation device.

Level of evidence

Prospective randomized controlled trial, Level I.     

Comparison between Nintendo Wii Fit and conventional rehabilitation on functional performance outcomes after hamstring anterior cruciate ligament reconstruction: prospective, randomized, controlled, double-blind clinical trial

Purpose

The aim of this prospective, randomized, controlled, double-blind clinical trial was to compare the outcomes, including knee strength, balance, coordination, proprioception and response time, of Nintendo Wii Fit with those of conventional rehabilitation on the subjects with anterior cruciate ligament reconstruction.

Methods

Thirty volunteer subjects were enrolled in either Wii Fit (n = 15; mean age, 29 ± 7 years) or conventional rehabilitation (n = 15; mean age, 29 ± 6 years) programmes from the first week up to 12th weeks of the operation. Endoscopic reconstruction of a completely ruptured ACL was performed by using graft harvested from hamstrings. Each subject underwent an individual therapeutic programme. Functional examinations included the measurements of the balance using modified star excursion balance test, coordination, proprioception and response time using functional squat system and strength of flexor and extensor muscles of the involved and uninvolved leg using an isokinetic machine.

Results

There was no significant difference between Wii Fit and conventional group in terms of isokinetic knee strength at 12th week, and dynamic balance, and functional squat tests including coordination, proprioception and response time at first, 8th and 12th weeks of the rehabilitation.

Conclusion

Two different 12-week-physiotherapy programmes following ACL reconstruction have the same affect on muscle strength, dynamic balance and functional performance values in both groups. We considered that the practice of Wii Fit activities like conventional rehabilitation could also address physical therapy goals, which included improving visual–perceptual processing, coordination, proprioception and functional mobility.

Level of evidence

Randomized, controlled trials with adequate statistical power, Level I.     

The influence of the intercondylar notch dimensions on injury of the anterior cruciate ligament: a meta-analysis

Purpose

The aim of this meta-analysis was to examine the effect of the intercondylar notch dimensions, intercondylar notch width index (NWI) and intercondylar notch width (NW), separately in anterior cruciate ligament (ACL) injury.

Methods

The PubMed and Wanfang database were searched through until 1 November 2011 to identify studies that met pre-stated inclusion criteria. Reference lists of retrieved articles were also reviewed. Two authors independently extracted information on the designs of the studies, the characteristics of the study participants, exposure and outcome assessments and control for potential confounding factors. Either a fixed- or a random-effects model was used to calculate the overall weighted mean difference (WMD).

Results

Sixteen studies (n = 4,291) were included (1,222 subjects in ACL-injured group and 3,069 subjects in the control group). Statistically significant differences were observed in the NWI (WMD, ?0.02; 95 % confidence interval, ?0.04 to ?0.01), and in the NW (WMD, ?2.15; 95 % confidence interval, ?3.09 to ?1.21) among the ACL-injured group when compared to the control group.

Conclusion

The meta-analysis findings concluded that narrow intercondylar notch dimensions were associated with the risk of ACL injury. A lower NWI or NW stenosis predisposes an individual to ACL injury. Further original studies should include more anatomical risk factors that could be associated with the risk of ACL injury.

Level of evidence

III.     

Increased chondrocyte seeding density has no positive effect on cartilage repair in an MPEG-PLGA scaffold

Purpose

This study investigates the effect of cell seeding density on cartilage repair in matrix-assisted chondrocyte implantation in vitro and in vivo.

Methods

In vitro: Four different cell seeding densities of human chondrocytes were seeded onto a porous methoxy-polyethylene glycol-polylactic-co-glycolic acid scaffold (MPEG-PLGA) polymer scaffold ASEED? (1.2 × 10⁶, 4.0 × 10⁶, 1.2 × 10⁷ and 2.0 × 10⁷ cells/cm³). The cartilage repair response was evaluated by relative gene expression of the chondrogenic markers sox9, collagen types I, II and X, and aggrecan, total DNA content and sulphated glycosaminoglycan synthesis. In vivo: Using a New Zealand white rabbit intercondylar osteochondral defect model, three different cell seeding densities (1.2 × 10⁶, 4.0 × 10⁶ and 1.2 × 10⁷ cells/cm³) were tested with an empty scaffold as control. The cartilage repair response was evaluated using O’Driscoll score.

Results

In vitro: A significant difference (p < 0.05) in total DNA content was found at day 2 but not at day 7. The low cell seeding densities yielded the highest GAG content (p < 0.001) at day 7. Collagen type I was highest (p < 0.01) at the lowest density at day 7. In vivo: No significant difference was found between the 4 groups.

Conclusions

No positive effect on cartilage repair was found using increased cell seeding density.

Level of evidence

Controlled experimental study, Level II.     

Gender differences following computer-navigated single- and double-bundle anterior cruciate ligament reconstruction

Purpose

Female patients not only demonstrate an increased risk for injury, but also a poorer response following anterior cruciate ligament (ACL) rupture. However, no study has investigated gender-related differences between computer-navigated single-bundle (SB) and double-bundle (DB) ACL reconstruction. The aim of this study was to evaluate the effects of gender on the outcome of computer-navigated SB and DB ACL reconstruction and to present reference values.

Methods

A retrospective review of 55 consecutive patients who underwent SB (15 males, 12 females) and DB (18 males, 10 females) ACL reconstruction with autogenous hamstring tendon grafts and showed a minimum follow-up of 24 months was conducted. Intraoperatively, the anteroposterior and rotational laxity were measured and the follow-up examination included pivot-shift testing, KT-1000 arthrometer testing, International Knee Documentation Committee (IKDC) form, the Lysholm score and Tegner score.

Results

Pre-operatively, female patients showed a significant higher internal rotation in (p < 0.001) both the SB and DB group. Regarding the post-operative reduction in internal rotation, females in the SB group revealed a greater reduction compared to males (p < 0.001), whereas females in the DB group revealed a significantly greater post-operative reduction in anterior–posterior translation (p = 0.04). Female patients following DB ACL reconstruction presented a significant worse IKDC score, Lysholm score and Tegner score compared to male patients. All score values of the female DB group were worse than in the female SB group. In contrast, male patients showed better results of all examined clinical scores following DB procedure compared to SB technique.

Conclusion

Female patients who underwent computer-navigated DB ACL reconstruction exhibited significantly worse outcome scores than males who underwent DB ACL reconstruction. The gender-based relationship between joint function and outcome after ACL reconstruction remains unclear and requires further investigation.

Level of evidence

Retrospective case–control series, Level III.     

Effect of muscle preserved on tendon graft on intra-articular healing in anterior cruciate ligament reconstruction

Purpose

The aim of this study was to determine the impact on intra-articular healing of muscle tissue retained on tendon grafts used for anterior cruciate ligament (ACL) reconstruction.

Methods

In an animal study on 40 New Zealand rabbits, a semi-tendon/semi-muscle graft (SSG) and a total tendon graft (TTG) were individually harvested from the Achilles tendons in each animal. After transecting the ACLs in both knees of each rabbit, SSG and TTG were randomly used on bilateral sides of the knee for ACL reconstruction. After 2, 4, and 8 weeks, functional scoring, gross observations, and histological evaluations of the repaired knees were performed (each time point; n = 10). Biomechanical testing was conducted on remaining animals at 8 weeks (n = 10).

Results

At 2, 4, and 8 weeks after surgery, there were no statistically significant differences in functional scores between the SSG group and TTG group (n.s.). As healing progressed, skeletal muscle on the SSG was gradually absorbed with a corresponding decrease in graft diameter, compared to TTG, at each time point (P < 0.001). However, healing and incorporation of the intra-articular graft in the SSG were more apparent than those in the TTG, based on histology. The vascularity and cellularity in the center of the sample were significantly greater in the SSG group than the TTG group at all the time points (P < 0.01). At 8 weeks, the SSG group’s ultimate failure load, yield load, and elongation at failure were significantly less than for the TTG group (P < 0.01). There were no significant differences in stiffness between the two groups with biomechanical testing (n.s.).

Conclusion

Results of this study indicate that muscle left on tendon grafts promotes intra-articular healing and remodeling of the graft in a rabbit model. However, excessive amounts of retained skeletal muscle weaken tendon graft’s strength for ACL reconstruction. Preserving small amounts of muscle on tendon grafts is feasible for improving the biological success of ACL reconstruction in humans.     

Sex comparison of familial predisposition to anterior cruciate ligament injury

Purpose

In an effort to identify risk factors for anterior cruciate ligament (ACL) injury, many potential risk factors have been proposed, including familial predisposition. However, no study has evaluated familial predisposition in male or females separately. The purpose of this study was to determine whether a familial predisposition to ACL injury exists in both males and females.

Methods

One hundred and twenty (78 males and 42 females) patients who had undergone surgical ACL reconstruction were recruited as the ACL group, and 107 patients (67 males and 40 females) that had undergone arthroscopic partial menisectomy, with no previous history of ACL injury, were recruited as the referent control group. A familial ACL injury and subject particulars questionnaire was completed.

Results

When all subjects were combined, the ACL group (20.0 %, 24 of 120) did not demonstrate a higher familial (first-degree relative) prevalence (n.s.) of ACL injury compared to the referent control group (15.0 %; 16 of 107 patients). When the data were stratified by sex, the male ACL group (19.2 %, 15 of 78) demonstrated a significantly higher familial (first-degree relative) prevalence (P = 0.02) of ACL injury compared to the male referent control group (7.5 %; 5 of 67 patients). There were no differences among the females (n.s.).

Discussion

The results of this study show that male patients with ACL tears are more likely to have a first-degree relative with an ACL tear compared to male referent control subjects. Future research is warranted to better delineate sex-specific risk factors for ACL injuries could help guide intervention programs aimed at preventative treatment strategies, especially in high-risk families.

Level of evidence

III.     

A novel nano-structured porous polycaprolactone scaffold improves hyaline cartilage repair in a rabbit model compared to a collagen type I/III scaffold: in vitro and in vivo studies

Purpose

To develop a nano-structured porous polycaprolactone (NSP-PCL) scaffold and compare the articular cartilage repair potential with that of a commercially available collagen type I/III (Chondro-Gide^®) scaffold.

Methods

By combining rapid prototyping and thermally induced phase separation, the NSP-PCL scaffold was produced for matrix-assisted autologous chondrocyte implantation. Lyophilizing a water–dioxane–PCL solution created micro and nano-pores. In vitro: The scaffolds were seeded with rabbit chondrocytes and cultured in hypoxia for 6 days. qRT–PCR was performed using primers for sox9, aggrecan, collagen type 1 and 2. In vivo: 15 New Zealand White Rabbits received bilateral osteochondral defects in the femoral intercondylar grooves. Autologous chondrocytes were harvested 4 weeks prior to surgery. There were 3 treatment groups: (1) NSP-PCL scaffold without cells. (2) The Chondro-Gide^® scaffold with autologous chondrocytes and (3) NSP-PCL scaffold with autologous chondrocytes. Observation period was 13 weeks. Histological evaluation was made using the O’Driscoll score.

Results

In vitro: The expressions of sox9 and aggrecan were higher in the NSP-PCL scaffold, while expression of collagen 1 was lower compared to the Chondro-Gide^® scaffold. In vivo: Both NSP-PCL scaffolds with and without cells scored significantly higher than the Chondro-Gide^® scaffold when looking at the structural integrity and the surface regularity of the repair tissue. No differences were found between the NSP-PCL scaffold with and without cells.

Conclusion

The NSP-PCL scaffold demonstrated higher in vitro expression of chondrogenic markers and had higher in vivo histological scores compared to the Chondro-Gide^® scaffold. The improved chondrocytic differentiation can potentially produce more hyaline cartilage during clinical cartilage repair. It appears to be a suitable cell-free implant for hyaline cartilage repair and could provide a less costly and more effective treatment option than the Chondro-Gide^® scaffold with cells.     

Decreased femoral head–neck offset: a possible risk factor for ACL injury

Purpose

Reduction in anterior cruciate ligament (ACL) injuries in young, active individuals continues to be a major goal in sports medicine. The purpose of this study was to determine the head–neck offset, as measured by AP pelvis alpha angles, in patients presenting to a single surgeon with isolated ACL and non-ACL knee injuries.

Methods

In a group of 48 patients with complete, primary ACL rupture and 42 controls with non-ACL injury (i.e., meniscus tear, cartilage defect), a single surgeon, blinded to the diagnosis, took radiographic measures of the AP alpha angle of both hips and the weight-bearing line at both knees. All knee pathology was confirmed with knee arthroscopy. Inclusion criteria included no previous hip or knee surgery, and long-leg standing alignment radiographic series completed at index visit.

Results

There was no difference in gender distribution, height, BMI or age between groups. ACL-injured patients had a significantly higher alpha angle (mean = 84, SD = 14) on the injured side than the controls (mean = 59, SD = 7, p < 0.0001). Ninety-four percent of the ACL-injured group had alpha angles over 60°, while only 35% of the non-ACL-injured group had alpha angles over 60° (p = 0.001). Those patients with alpha angle over 60° were 27 times more likely (95% CI 6.4–131) to be in the ACL injury group than those patients with alpha angle 60° or less (p = 0.001).

Conclusion

Our findings establish an important preliminary correlation between ACL injury and diminished femoral head–neck offset, as characterized by abnormal, elevated alpha angles.

Level of evidence

Prognostic study, Level III.     

Biomechanical comparison of different graft positions for single-bundle anterior cruciate ligament reconstruction

Purpose

Recent reports have highlighted the importance of an anatomic tunnel placement for anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to compare the effect of different tunnel positions for single-bundle ACL reconstruction on knee biomechanics.

Methods

Sixteen fresh-frozen cadaver knees were used. In one group (n = 8), the following techniques were used for knee surgery: (1) anteromedial (AM) bundle reconstruction (AM–AM), (2) posterolateral (PL) bundle reconstruction (PL–PL) and (3) conventional vertical single-bundle reconstruction (PL-high AM). In the other group (n = 8), anatomic mid-position single-bundle reconstruction (MID–MID) was performed. A robotic/universal force-moment sensor system was used to test the knees. An anterior load of 89 N was applied for anterior tibial translation (ATT) at 0°, 15°, 30° and 60° of knee flexion. Subsequently, a combined rotatory load (5 Nm internal rotation and 7 Nm valgus moment) was applied at 0°, 15°, 30° and 45° of knee flexion. The ATT and in situ forces during the application of the external loads were measured.

Results

Compared with the intact ACL, all reconstructed knees had a higher ATT under anterior load at all flexion angles and a lower in situ force during the anterior load at 60° of knee flexion. In the case of combined rotatory loading, the highest ATT was achieved with PL-high AM; the in situ force was most closely restored with MIDMID, and the in situ force was the highest AM–AM at each knee flexion angle.

Conclusion

Among the techniques, AM–AM afforded the highest in situ force and the least ATT.