Patella fracture and proximal patellar tendon rupture following arthroscopic anterior cruciate ligament reconstruction

Current trends in graft choice for primary anterior cruciate ligament reconstruction - part II: In-vivo kinematics, patient reported outcomes, re-rupture rates, strength recovery, return to sports and complications

Postoperative patient satisfaction after anterior cruciate ligament reconstruction (ACL-R) is influenced mainly by the degree of pain, the need for reoperation, and functional performance in daily activities and sports. Graft choice has shown to have an influence on postoperative outcomes after ACL-R. While patient reported outcomes measurements do not differ between graft options, evidence shows that normal knee kinematics is not fully restored after ACL-R with an increase in postoperative anterior tibial translation (ATT). Postoperative graft rupture rates seem to favor bone-patella-tendon-bone (BPTB) and quadriceps tendon (QT) autografts over HT or allografts. While return to sports rates seem comparable between different graft types, postoperative extensor strength is reduced in patients with BPTB and QT whereas flexion strength is weakened in patients with HT. Postoperative donor site morbidity is highest in BPTB but comparable between HT and QT. With all graft options having advantages and drawbacks, graft choice must be individualized and chosen in accordance with the patient.

Is there significant regeneration of the hamstring tendons after harvest for ACL reconstruction? A systematic review of literature

BACKGROUND

Regeneration potential of Hamstring tendons after harvest assumes significant clinical relevance as its use has become widespread today. Methods which best assess the regeneration, extent and type of regeneration, plus issues related to functional loss are important for the surgeon to know. This review looks at the literature to find answers to the above questions.

PURPOSE

To summarize the evidence in support of hamstring tendon regeneration, and the most appropriate modality for evaluation of regeneration. Additionally, to evaluate the regeneration in terms of complete or partial, extent and its impact on strength deficit and functional outcomes.

METHODS

We did a systematic review of literature through specified search engines and identified 30 of 285 studies to be relevant (19 prospective and 11 retrospective).

RESULTS

Evaluation of above data suggests tissue regeneration at harvest sites does occur (78.9% of semitendinosus and 42.7% of gracilis tendons), but this regeneration is variable. No established definition of regeneration exists; MRI is an adequate tool to identify regeneration, while biopsy is confirmative. USG is a cost-effective screening method and can document distal progress of regenerate. Semitendinosus and gracilis tendons regenerate at different rates and extents, and often fuse together, but there is no evidence to state that one regenerates better than the other. Proximal retraction of the muscle-tendon junction occurs, along with some atrophy, which affects function to a variable extent. Strength deficits may persist, but they may not convert to significant functional deficits.

CONCLUSION

There is variable hamstring regeneration after harvest, with poorly defined definition of "regeneration". Some changes in the muscle itself, abnormal distal insertion and absence of regeneration in some are documented, along with strength deficits. Although overall functional deficits have been reported to be minimal, a definite change in the anatomy of the medial hamstrings is a factor to be kept in consideration. More information is needed about the long-term consequences.

Peroxisome proliferator-activated receptor-γ and its related pathway in bone marrow mesenchymal stem cell differentiation co-cultured with mechanically stretched ligament fibroblasts

The occurrence of pelvic floor dysfunctional disease (PFD) is closely related with elasticity, toughness, and functional changes of the connective tissue of the pelvic support tissue. Bone marrow mesenchymal stem cells (BMSCs) have been confirmed to have the capacity to differentiate into a variety of cell types such as osteoblasts, chondroblasts, adipocytes and fibroblasts. Therefore, BMSCs have the potential to improve the clinical outcomes for PFD. Peroxisome proliferator-activated receptor-γ (PPAR-γ), a ligand activated transcription factor, has acquired a great deal of attention as it is involved in the fibrosis and cell differentiation. However, how it is regulated during the process of the differentiation of BMSCs into fibroblasts remains to be defined. The present study investigated the underlying mechanisms of PPAR-γ effect of mechanical stretch on the differentiation of BMSCs induced by pelvic ligament fibroblasts. PPAR-γ expression was decreased during the differentiation of BMSCs into fibroblasts by co-cultured stretched fibroblasts. Addition of transforming growth factor-β1 (TGF-β1) reduced PPAR-γ expression and promoted the differentiation of BMSCs. With the employment of endogenous ligand, activation of PPAR-γ suppressed the BMSC differentiation. Similar effects were also observed with overexpression of PPAR-γ gene. In addition, decrease of PPAR-γ by the use of shRNA targeting rat PPAR-γ significantly contributed to BMSC differentiation to fibroblasts. These results indicate that PPAR-γ negatively regulates the differentiation of BMSCs into fibroblasts.

Tenascin-C expression and its associated pathway in BMSCs following co-culture with mechanically stretched ligament fibroblasts

The occurrence of pelvic organ prolapse (POP) is closely associated with alterations in the extracellular matrix proteins of the supporting ligament. Bone marrow mesenchymal stem cells (BMSCs) have the potential to differentiate into a variety of cell types, including osteoblasts, chondroblasts and adipocytes. Therefore, BMSCs have the potential to improve the clinical outcomes of POP. Tenascin-C is a large glycoprotein that is present in the ECM and is involved in morphogenetic movements, and tissue patterning and repair. The aim of the present study was to investigate the effect of mechanical stretching on tenascin-C expression during the differentiation of BMSCs induced by pelvic ligament fibroblasts. BMSCs were isolated from 7-day-old Sprague Dawley rats. Fibroblasts were obtained from rat pelvic ligaments and, at the fourth passage, were subjected to 10% deformation with 1 Hz, periodic one-way mechanical stretch stimulation, followed by co-culture with BMSCs. The co-culture with stretched fibroblasts increased tenascin-C and transforming growth factor (TGF)-β expression levels, compared with groups without mechanical stimulation. Neutralizing anti-TGF-β1 antibodies, and inhibitors of TGF-β receptor, mitogen-activated protein kinase (MAPK) kinase and MAPK, decreased tenascin-C expression levels induced by TGF-β and mechanical stretching. The results of the present study suggested that the regulation of tenascin-C expression levels in BMSCs co-cultured with mechanically stretched pelvic ligament fibroblasts is mediated via the soluble growth factor TGF-β and the MAPK signaling pathway. In addition, these results indicated that in an indirect co-culture system, pelvic ligament fibroblasts with mechanical stretch stimulation may promote the synthesis of tenascin-C and BMSC differentiation into pelvic ligament fibroblasts.

Morphologic Characteristics and Strength of the Hamstring Muscles Remain Altered at 2 Years After Use of a Hamstring Tendon Graft in Anterior Cruciate Ligament Reconstruction

BACKGROUND

The hamstring tendon graft used in anterior cruciate ligament (ACL) reconstruction has been shown to lead to changes to the semitendinosus and gracilis musculature.

HYPOTHESIS

We hypothesized that (1) loss of donor muscle size would significantly correlate with knee muscle strength deficits, (2) loss of donor muscle size would be greater for muscles that do not experience tendon regeneration, and (3) morphological adaptations would also be evident in nondonor knee muscles.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Twenty participants (14 men and 6 women, mean age 29 ± 7 years, mean body mass 82 ± 15 kg) who had undergone an ACL reconstruction with a hamstring tendon graft at least 2 years previously underwent bilateral magnetic resonance imaging and subsequent strength testing. Muscle and tendon volumes, peak cross-sectional areas (CSAs), and lengths were determined for 12 muscles and 6 functional muscle groups of the surgical and contralateral limbs. Peak isokinetic concentric strength was measured in knee flexion/extension and internal/external tibial rotation.

RESULTS

Only 35% of the patients showed regeneration of both the semitendinosus and gracilis tendons. The regenerated tendons were longer with larger volume and CSA compared with the contralateral side. Deficits in semitendinosus and gracilis muscle size were greater for muscles in which tendons did not regenerate. In addition, combined hamstring muscles (semitendinosus, semimembranosus, and biceps femoris) and combined medial knee muscles (semitendinosus, semimembranosus, gracilis, vastus medialis, medial gastrocnemius, and sartorius) on the surgical side were reduced in volume by 12% and 10%, respectively. A 7% larger volume was observed in the surgical limb for the biceps femoris muscle and corresponded with a lower internal/external tibial rotation strength ratio. The difference in volume, peak CSA, and length of the semitendinosus and gracilis correlated significantly with the deficit in knee flexion strength, with Pearson correlations of 0.51, 0.57, and 0.61, respectively.

CONCLUSION

The muscle-tendon properties of the semitendinosus and gracilis are substantially altered after harvesting, and these alterations may contribute to knee flexor weakness in the surgical limb. These deficits are more pronounced in knees with tendons that do not regenerate and are only partially offset by compensatory hypertrophy of other hamstring muscles.

Hamstring Tendon Regeneration After Harvest for Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To assess whether the portions of the semitendinosus and gracilis tendons harvested for anterior cruciate ligament reconstruction have the potential to regenerate and, if so, to evaluate the histologic properties and actual function of this newly formed tissue.

METHODS

We performed a comprehensive search of CINAHL (Cumulative Index to Nursing and Allied Health Literature), Embase, Medline, the Cochrane Central Registry of Controlled Trials, and SPORTDiscus from inception of the databases to July 2014, using various combinations of keywords. Studies focusing on hamstring tendon and muscle regeneration through imaging and histology, as well as on the related functional outcomes, were selected. We included studies assessing evidence of tissue regeneration with imaging (magnetic resonance imaging, 3-dimensional computed tomography, ultrasonography) or with histologic examination of biopsy samples (or a combination thereof).

RESULTS

Nineteen articles were included in this review, with a total of 400 patients observed. The overall rate of tissue regeneration was 86.0%, with similar values shown in most studies regardless of the methodology of the assessment. Biopsy confirmed that the tissue found at the site in 74% of the cases showed typical histologic features of the tendon. The mean modified Coleman Methodology Score of the studies included was 52.7 points, showing a modest methodologic quality for the studies published to date.

CONCLUSIONS

In over 85% of the cases analyzed, regeneration signs of the harvested tendon were found through different imaging and histologic methodologies. A torque deficit in deep knee flexion is always present postoperatively, but the cause for this is still unclear. There is a need for better-designed trials featuring a higher level of evidence to further investigate this matter, and the effects of postoperative care and the surgical approach used on the regeneration process should be analyzed in the future.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II, III, and IV studies.

Serial changes in knee muscle strength after anterior cruciate ligament reconstruction using hamstring tendon autografts

PURPOSE

The purpose of this study was to evaluate serial changes in quadriceps and hamstring muscle strength over the first postoperative year in patients who underwent anterior cruciate ligament (ACL) reconstruction with an autologous hamstring tendon graft and to reveal which of these 2 muscles lost more strength and recovered more slowly after autologous hamstring ACL reconstruction.

METHODS

Isokinetic muscle strength was measured preoperatively and at 6 months and 1 year postoperatively in 20 patients who underwent ACL reconstruction. The maximal torque (60°/s) and total work (180°/s) of the quadriceps and hamstring were evaluated using an isokinetic testing device. The isokinetic muscle strength and endurance of the injured legs were expressed as percentages of those of the uninjured legs at the same time point.

RESULTS

Both quadriceps and hamstring muscle strength at 60°/s and endurance at 180°/s of the injured relative to the uninjured leg was 50% preoperatively. Quadriceps muscle strength and endurance of the injured leg increased to 70% at 6 months and 80% at 1 year postoperatively, whereas hamstring muscle strength and endurance increased to 80% at 6 months and 80% at 1 year.

CONCLUSIONS

Knee muscle strength recovered progressively after ACL reconstruction using autologous hamstring tendons but did not fully recover, being about 80% that of the uninjured leg even 1 year after surgery.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

ACL ideal graft: MRI correlation between ACL and humstrings, PT and QT

Objective

The objective of this study was to measure in MRI scans, the size of the origin, insertion and length of the anterior cruciate ligament and possible graft for reconstruction surgery in case of injury. Besides this, there was a cross between statistical data to test the hypothesis of proportional relationship between these anatomical extent.

Materials and methods

52 MRI examinations performed between 2008 and 2011 were valued at random in a longitudinal retrospective epidemiological study. To measure the width of the ACL was used coronal oblique to the length of the sagittal section, for inserting the tibial coronal femoral insertion and was also used oblique coronal section.

Results

The average diameter of the ACL was 4.80 mm (3.1–8.3 mm), with a length of 3.8 cm (2.85–4.5 cm). The origin ranged from 9.7 mm to 15.4 mm. The average insertion on the tibia was 13.3 mm. The average diameter of the semi-tendinous was 4.38 mm and the average diameter was 3.42 mm gracilis. The quadriceps presented diameter of 7.67 mm, a length of 35.34 mm and 4.54 mm patellar tendon diameter and 26.62 mm in average length.

Conclusion

These data provide important information for the pre-operative surgeon, facilitating preoperative planning and providing viable alternatives and avoiding inadequate grafts.

Bifocal disruption of the knee extensor mechanism: a case report and literature review

Bifocal disruption of the knee extensor mechanism is a rare injury. Bifocal proximal and distal avulsion fracture of the patella tendon is extremely rare in adults. Here, the authors report the case of an 84-year-old male patient who developed simultaneous avulsion fracture of the patella tendon from the inferior pole of the patella and the tibial tuberosity. Open reduction and internal fixation were performed, and at 12 months postoperatively, an excellent functional result was obtained.

Tear patterns, surgical repair, and clinical outcomes of patellar tendon ruptures after anterior cruciate ligament reconstruction with a bone-patellar tendon-bone autograft

BACKGROUND

Patellar tendon ruptures are rare after graft harvest for anterior cruciate ligament (ACL) reconstruction. Few reports are available in the literature.

PURPOSE

To report the common tear patterns and results of treatment with tendon repair and cable augmentation.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

All tendon ruptures were repaired to bone with suture anchors and augmented with a Dall-Miles cable, followed by an aggressive rehabilitation protocol. The tear location was recorded. Range of motion, strength, and subjective survey testing were conducted preoperatively and postoperatively.

RESULTS

Thirteen patellar tendon ruptures were found from our database of 5364 ACL reconstructions, for an incidence of 0.24%. Seven ruptures occurred from the patellar origin medially and the tibial attachment laterally in a Z-shaped pattern. Four were completely distal, and 2 were completely proximal ruptures. All patients exhibited early flexion loss, but 11 of 13 patients maintained full, terminal hyperextension throughout treatment. The mean postoperative side-to-side flexion deficit was 33° at 1 month, 6° at 3 months, and 3° at latest follow-up at a mean of 4.8 years after tendon repair (range, 1-16 years). By International Knee Documentation Committee (IKDC) criteria, 10 patients had normal flexion, and 3 were nearly normal at latest follow-up. Twelve patients had normal extension, and 1 had nearly normal extension at latest follow-up. Mean isokinetic quadriceps muscle strength was 68.7% of the other side at 3 months after repair and 100.0% at latest follow-up, occurring at a mean of 47.5 months (range, 12-120 months). At a mean of 2 years (range, 1-4 years) after repair, the mean modified Noyes subjective score was 89.8 ± 9.2.

CONCLUSION

Patellar tendon ruptures are rare after ACL graft harvest. These ruptures usually occur in either a proximal-medial and distal-lateral pattern or an entirely distal pattern, in contrast to the proximal-only tear pattern commonly observed in unharvested patellar tendons. Good objective and subjective results were achieved with repair of postoperative patellar tendon ruptures using suture anchors and Dall-Miles cable augmentation, followed by aggressive, immediate range of motion exercises.

The effects of hamstring harvesting on outcomes in anterior cruciate ligament-reconstructed patients: a comparative study between hamstring-harvested and -unharvested patients

PURPOSE

The purpose of this study was to evaluate the effects of hamstring harvesting in patients after anterior cruciate ligament (ACL) reconstruction by comparing groups with and without hamstring harvesting.

METHODS

We evaluated the effect of hamstring harvesting in 73 consecutive patients who underwent ACL reconstruction: 39 patients whose hamstrings were harvested for autografts (group H) were compared with 34 patients who received allografts during the same time period (group C [control]). The cases and controls were compared by analyzing the following variables: age, height, weight, mean follow-up period, type of tissue used, and meniscal surgery. Outcomes were assessed by the Lysholm knee score, Tegner activity score, and KT-2000 side-to-side difference (MEDmetric, San Diego, CA), as well as functional performance tests. The flexor deficit and isokinetic peak torque for knee flexion were measured in the sitting position (0° to 90°), and the flexion torque at 90° was measured in the prone position (60° to 120°).

RESULTS

Although significant knee flexion weakness after ACL reconstruction was observed, a significantly greater knee flexor deficit was found in autograft patients than in allograft patients (P < .001). No differences were found between groups in terms of clinical and functional results regardless of hamstring harvesting. The performance of both study groups in all 4 functional tests were significantly correlated with flexor deficit in the sitting position (P < .05) but not in hyperflexion. Significant flexor deficits in both normal and hyperflexed positions were noted in both groups when compared with the unaffected knee (group H, P < .001; group C, P = .002).

CONCLUSIONS

These results indicate significant knee flexion weakness compared with the unaffected knee after ACL reconstruction regardless of hamstring harvesting. Moreover, the greater increase in knee flexor deficit in the hamstring-harvested group compared with the allograft group was statistically significant. However, clinical and functional outcomes were similar between the groups.

LEVEL OF EVIDENCE

Level III, case-control study.

Knee flexor strength after ACL reconstruction: comparison between hamstring autograft, tibialis anterior allograft, and non-injured controls

Hamstring muscle group dysfunction following anterior cruciate ligament reconstruction (ACL) using a semitendinosus-gracilis autograft is a growing concern. This study compared the mean peak isometric knee flexor torque of the following three groups: subjects 2 years following ACL reconstruction using semitendinosus-gracilis autografts (Group 1), subjects 2 years following ACL reconstruction using tibialis anterior allografts (Group 2), and a non-injured, activity-level-matched control group (Group 3). We hypothesized that Group 1 would have greater mean involved lower extremity peak isometric knee flexor torque deficits than the other groups. Handheld dynamometry with subjects in prone and the test knee at 90 degrees flexion was used to determine bilateral peak isometric knee flexor torque. Group 1 (86.4 +/- 11) and Group 2 (80.5 +/- 13) had similar 2000 IKDC Subjective Knee Evaluation Form scores (P = NS). Group 1 had a mean involved lower extremity peak isometric knee flexor torque deficit of -17.0 +/- 14 Nm. Group 2 had a mean involved lower extremity peak isometric knee flexor torque deficit of -0.8 +/- 9 Nm. Group 3 (control) had a mean left and right lower extremity peak isometric knee flexor torque difference of -0.7 +/- 14 Nm. Group 1 had decreased involved lower extremity peak isometric knee flexor torque compared to Groups 2 and 3 (two-way ANOVA; group x side interaction P < 0.05, Tukey HSD = 0.008). Long-term knee flexor strength deficits exist following hamstring autograft use for ACL reconstruction that does not occur when a tibialis anterior allograft is used. Early identification of impaired knee flexor strength among this group and modified rehabilitation may reduce these deficits. Adding quantitative biomechanical testing of sprinting and sudden directional change movements to the standard physical therapy evaluation will better elucidate the clinical and functional significance of the observed knee flexor strength impairments and aid in determining sport specific activity training readiness.

Intra-articular distal femur fracture extending from an expanded femoral tunnel in an anterior cruciate ligament (ACL) reconstructed knee: a case report

Anterior cruciate ligament (ACL) reconstruction is a popular surgery with overall good results. However, postoperative fracture is a serious, albeit, rare complication. Femoral tunnel lysis may cause a stress riser effect leading to distal femur fractures after ACL reconstruction. We report a case in which a patient who underwent ACL reconstruction surgery 18 months before a low-energy twisting mechanism suffered a distal femur fracture requiring open reduction internal fixation.

Stress avulsion of the tibial tuberosity after tension band wiring of a patellar fracture: a case report

Introduction

To the best of our knowledge there is no other report of an elderly patient who was surgically treated for a patellar fracture with tension band wiring and who subsequently suffered from an avulsion fracture of the tibial tuberosity. The combination of a patellar fracture and avulsion of the patellar ligament has only been described as complication after bone-patellar tendon-bone anterior cruciate ligament reconstructions. However, due to demographic changes and more elderly patients treated this injury may become more frequent in future.

Case presentation

We present the case of an 81 year old female who sustained an oblique patellar fracture after a direct contact injury of the left knee when falling on ice. Consequently the patellar fracture was openly reduced and stabilized with tension band wiring. The follow-up was uneventful till three months after surgery when the patient noticed a spontaneous avulsion fracture of the tibial tuberosity (Ogden type 3). The tibial tuberosity fragment was reattached with two non-resorbable sutures looped around two modified AO cortical 3.5 mm long neck screws. Intraoperatively multiple bone cysts were seen. Biopsies were not taken to prevent further fragmentation of the tibial tuberosity. The patient was followed up with anteroposterior and lateral full weight bearing radiographs and clinical assessment at 6, 12 weeks and 6 months after surgery. Recovery was completely pain free with full satisfaction.

Conclusion

In conclusion in elderly patients with a patella fracture a possible associated but not obvious fracture of the tibial tuberosity should be ruled out and the postoperative rehabilitation protocol after tension band wiring of the patella might have to be individually adjusted to bone quality and course of the fracture.

[Late patellar tendon rupture 10 years after anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft]

Autologous transplantation of the central third of the patella tendon with a bone-patellar tendon-bone (BTB) graft is one of the most commonly used techniques for anterior cruciate ligament (ACL) reconstruction. Frequently chosen alternative sources include semitendinosus and gracilis tendon autografts. The differences of opinion regarding graft sources mainly result from comparison of outcome and complications. Although higher donor site morbidity and postoperative extensor mechanism complications are postulated for bone-patellar tendon-bone grafts, patellar tendon ruptures following anterior cruciate ligament reconstruction are rarely reported in the literature. These predominantly occur during the early postoperative period. We present the case of a patellar tendon rupture in a healthy 36-year-old man, who suffered a skiing accident 10 years after uneventful ACL reconstruction with a BTB graft.

Immunohistochemical study of angiogenesis after local administration of platelet-rich plasma in a patellar tendon defect

A full thickness defect was made in the central portion of the patellar tendon of 48 New Zealand white rabbits. Platelet-rich plasma (PRP) gel was then applied and filled the tendon defect. The same procedure was performed in the control group, without the application of PRP. Animals were sacrificed after one, two, three, and four weeks. Histological and immunohistochemical analyses using a monoclonal antibody against CD31 were performed. The histological examination showed a superior healing process in the PRP group compared with the control group. Especially in the third week, the tissue formed in the PRP group was more mature and dense with less elastic fibres remaining. Neovascularisation was significantly higher in the PRP group during the first two weeks and significantly lower in the third and fourth weeks (p < 0.0001). Histological examination and study of angiogenesis showed that the application of PRP enhances and accelerates the tendon healing process.

The incidence of acute patellar tendon harvest complications for anterior cruciate ligament reconstruction

PURPOSE

This study was performed to determine the incidence of acute bone-patellar tendon-bone autograft harvest complications after anterior cruciate ligament (ACL) reconstruction.

METHODS

Over a nearly 20-year period (September 1986 to April 2006), 1,725 consecutive patients underwent primary ACL reconstruction using bone-patellar tendon-bone autograft by 3 fellowship-trained sports medicine surgeons at our institution. Three acute complications related to patellar tendon harvest were identified from surgical databases, and the charts of these patients were reviewed.

RESULTS

In this series of 1,725 consecutive patients, 3 acute complications (0.2%) related to patellar tendon harvest were noted. These complications consisted of 2 patellar fractures (1 intraoperative and 1 postoperative) and 1 postoperative patellar tendon rupture. All 3 patients healed and went on to satisfactory outcomes.

CONCLUSIONS

A 0.2% overall acute complication rate related to patellar tendon harvest for primary ACL reconstruction supported our hypothesis. Bone-patella tendon-bone autograft remains a safe and viable choice for surgeons performing ACL reconstruction.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Hamstring tendons regeneration after ACL reconstruction: an overview

Despite the long lasting research the ideal method of reconstructing the ACL has not been found so far. The last year's attention has shifted to the use of the multistrand hamstring tendon grafts. High ultimate tensile load, multiple-bundle replacement that better approximates the anatomy of the normal ACL and low donor site morbidity are the main advantages of this ACL replacement graft. These theoretical advantages have been multiplied when surprisingly studies have shown that semitendinosus and gracilis tendons actually regenerate after harvesting for use as ACL autografts. In this review article we summarize the current knowledge concerning the hamstring regeneration and we focus on issues that have clinical relevance or issues that have not been answered so far.

Wrist circumference is related to patellar tendon thickness in healthy men and women

The efficacy of dominant wrist circumference measurements to predict dominant lower extremity patellar tendon thickness at regions of interest for bone-patellar tendon-bone (BPTB) autograft harvest was studied among 24 healthy men and women. Dominant wrist circumference displayed good relationships with dominant lower extremity patellar tendon thickness as determined by two-dimensional diagnostic ultrasound. This initial screening method may assist surgeons as they consider graft selection for patients who may be at risk for developing or exacerbating preexisting patellofemoral joint or knee extensor mechanism conditions with BPTB autograft harvest.

Intraoperative incidents and complications in primary arthroscopic anterior cruciate ligament reconstruction

PURPOSE

To analyze intraoperative incidents and complications in primary arthroscopic anterior cruciate ligament reconstruction (ACLR) with bone-patellar tendon-bone (BPTB) and quadruple hamstring semitendinosus and gracilis (STG) grafts.

METHODS

From January 1999 to June 2004, we performed 330 BPTB and 96 STG procedures. Intraoperative incidents and complications were recorded for each case.

RESULTS

Our overall intraoperative incident and complication rate was 9.6% and was higher in the STG group (13.5%) than in the BPTB group (8.7%). In the BPTB group, combined incidents and complications according to stage of the procedure consisted of graft harvesting, 4 cases (1.21%); tunnel placement, 9 cases (2.7%); and graft fixation, 15 cases (4.5%). In the STG group, combined incidents and complications included graft harvesting, 8 cases (8.3%); tunnel placement, 1 case (1%); graft fixation, 3 cases (3.1%); and others, 1 case (1%). In 4 patients (0.9%), we had to change the technique from BPTB to STG and vice versa. In 2 STG cases, conversion of the technique was required because of graft-related problems; in the third case, it was necessary because of fixation. One BPTB was converted to STG because the graft was completely transected as a result of improper screw fixation technique.

CONCLUSIONS

None of the encountered incidents and complications had an adverse effect on final stability or on range of motion in operated knees. All incidents and complications were due to technical errors that occurred during graft harvesting, tunnel placement, or graft fixation. It is known that technical errors are preventable if careful surgical technique is followed. The surgeon must be well versed in various reconstruction techniques to be able to detect and resolve forthcoming incidents or complications. Backup implants are mandatory.

LEVEL OF EVIDENCE

IV, therapeutic case series.

Tendon regeneration: an anatomical and histological study in sheep

Utilization of the hamstring tendon in reconstruction of the anterior cruciate ligament (ACL) has become common in recent years. In MRI studies regeneration potential in harvested tendon has been observed. In the present study, 20 legs from ten sheep, which underwent 10 cm segment resection of tendon of musculus extensor digitalis lateralis (MEDL) were used. The sheep were killed 6 months after the operation and regenerated tendons were examined macroscopically and histologically. Dissection was performed in the tendon resection area and specimens were reharvested for histological examination. Regeneration of the tendon with normal anatomical topographies was found in all legs. Regeneration occurred on both sides of the resected tendon simultaneously. Regeneration was muscle-like in the proximal side but it was tendon-like in the distal side. The developed tendon was fused to the joint capsule and to the fascia at the joint line in all specimens. This study indicates that tendon has a potential for regeneration.

Semitendinosus regrowth: biochemical, ultrastructural, and physiological characterization of the regenerate tendon

BACKGROUND

Previous studies have suggested that hamstring tendons can regenerate following harvesting for anterior cruciate ligament reconstruction.

HYPOTHESIS

This "neo-tendon" is a true, functional tendon, not scar tissue.

STUDY DESIGN

Controlled laboratory study.

METHODS

Semitendinosus tendons were harvested from 35 New Zealand white rabbits using a standard tendon stripper. The rabbits were sacrificed 9 to 12 months following the index procedure and thoroughly evaluated.

RESULTS

Thirty-one rabbits were available at the time of sacrifice. The neo-tendon was present in 26 rabbits but was highly variable in size and location of its tibial insertion. Histologic and immunohistochemical staining confirmed that the regenerate tissue was indeed tendon with normal cellularity, organization, and immunolocalization of type I collagen. Electron microscopy showed regeneration of organized collagen tissue that simulated native tendon but with a smaller cross-sectional diameter. Functionally, the neo-tendon was able to transmit force across the musculotendinous junction but at a significantly slower rate than the opposite, control leg. Biomechanical properties of the neo-tendon were significantly less than the control side. Biochemical analysis revealed that the neo-tendons contained glycosaminoglycans and collagen, but levels were significantly lower than normal tendons.

CONCLUSIONS

Semitendinosus tendons regenerate with biologically reactive tendinous tissues in an animal model. This tissue has many of the characteristics of a normal tendon but appears to be inferior to the original musculotendinous unit at 9- to 12-month evaluation. Further characterization of the "lizard tail phenomenon" is still needed.

CLINICAL RELEVANCE

Hamstring tendon regrowth may have a dramatic impact on postoperative function of patients who undergo anterior cruciate ligament reconstruction with these tendons. Further modulation of this regeneration may further reduce graft harvesting morbidity.

The changes in mechanical properties of regenerated and residual tissues in the patellar tendon after removal of its central portion

OBJECTIVE

To know the temporal changes of the mechanical properties of the regenerated and the residual tissues in the patellar tendon after removal of the central portion.Design. The regenerated and the residual tissues were compared to sham-operated tendons.

BACKGROUND

Although the structural properties of the whole patellar tendon after removal of the central portion have been investigated, no studies have distinguished between the regenerated and the residual tissues.Methods. For 52 skeletally mature rabbits, a full-thick, segmental defect was made at the central portion of the right patellar tendon, while a sham operation performed in the left tendon. At 3, 6, 12, and 24 weeks, we evaluated the mechanical properties and fibroblast density of the regenerated and the residual tissues as well as the blood flow and tissue dimensions of the patellar tendon. In addition, non-treated patellar tendons from six rabbits were served as the control for mechanical testing.

RESULTS

The tangent modulus and the tensile strength of the regenerated tissue progressively increased with time. On the other hand, these parameters of the residual tendinous portion decreased until 6 weeks, although they gradually increased thereafter. The tensile strength of the regenerated and the residual tissues at 24 weeks were approximately 80% and 75%, respectively, of the non-treated, control tendon. Abundant blood flow and cell proliferation were observed in the regenerative tissue until 6 weeks.

CONCLUSION

The mechanical properties of the regenerated and the residual tissues after removal of the central portion in the patellar tendon are much different from those of the original tendon.

RELEVANCE

The present study showed inferior mechanical properties of the residual and the regenerated tissues for up to 24 weeks after removal of the central portion in the patellar tendon. Therefore, the aggressive rehabilitation that applies excessive load to the patellar tendon should be avoided at an early stage after harvesting the tendon for ligament reconstruction.

Complications in anterior cruciate ligament surgery

There are many potential problems associated with ACL surgery; however, careful attention to detail can prevent problems from occurring or provide corrective options in the event they do occur. Multiple backup options are not only desirable but also essential to a successful outcome. By following these guidelines, ACL surgery can have good long-term results and return the recreational or higher-level athlete to sports participation.

A biomechanical analysis of four different methods of harvesting bone-patellar tendon-bone graft in porcine knees

BACKGROUND

Anterior cruciate ligament reconstruction with use of bone-patellar tendon-bone graft is commonly performed to treat functional instability of the knee after injury of the anterior cruciate ligament. Patellar fracture is an underreported complication of this procedure, yet it may be a career-ending injury for a professional athlete. The purpose of this study was to design a new technique to procure the patellar bone plug when reconstructing the cruciate ligament with use of patellar tendon.

METHODS

Fifty-eight knees were harvested from eighteen to twenty-four-month-old pigs. Bone plugs of four geometrical shapes were cored out of the patellae from forty knees (four plug shapes for each of ten knees). Ten knees had no graft removed. Fifty knees were tested for the effects of a single impact. Eight knees (two plug shapes for each of four knees) were tested for the effects of repeated impacts. Data were analyzed statistically with use of an ordinal logistic model. The probability of impact failure of the patella at different energy levels was calculated.

RESULTS

Impact energy has been shown to have a significant effect on the outcome (p < 0.001). When controlling for energy level, there was a significant difference between the sharp and round corners (p < 0.01). The ordinal logistic model was found to be very good for predicting the outcome of impact testing. The impact energy required to create a 1% probability of complete fracture was 7 J for a patella with a sharp-cornered plug defect, 17 J for a patella with a trapezoidal plug, 22 J for a patella with a sharp-cornered defect with a drill-hole at the corner, 40 J for a patella with a round-cornered defect, and about 49 J for a normal patella. Repeat impact testing substantially damaged the patellae with sharp-cornered defects, as they failed earlier at a lower energy and after a lower number of impacts than did the patellae with round-cornered defects.

CONCLUSIONS

We propose the use of the round-cornered patellar bone plug when bone-patellar tendon-bone graft is harvested for anterior cruciate ligament reconstruction, to further reduce the small likelihood of a patellar fracture occurring intraoperatively or in the early postoperative rehabilitation phase.

Semitendinosus muscle in anterior cruciate ligament surgery: Morphology and function

PURPOSE

To evaluate the fate of the hamstring muscles in general and the semitendinosus muscle in particular, after anterior cruciate ligament (ACL) reconstruction with an autologous semitendinosus tendon graft from the ipsilateral side.

TYPE OF STUDY

Prospective consecutive case series investigation.

METHODS

Included were 16 consecutive patients, 14 male and 2 female, with a mean age of 26 years. The inclusion criterion was chronic unilateral ACL insufficiency with no concomitant knee ligament injuries. ACL reconstruction was performed with a quadruple semitendinosus tendon graft using the EndoButton technique (Acufex, Mansfield, MA). Intraoperatively, muscle specimens were taken from the semitendinosus muscle on the harvested side. Follow-up at a minimum of 6 months included clinical examination, isokinetic strength performance, magnetic resonance imaging (MRI) of the thigh and knee, and ultrasound-guided muscle biopsy procurement from the semitendinosus muscle for histochemical and enzymatic analyses.

RESULTS

Of the patients, 75% showed regeneration of their semitendinosus tendons. The neotendons all inserted below the knee joint where they had fused with the gracilis tendon to a conjoined tendon inserting in the pes anserinus. The semitendinosus muscle had a smaller cross-sectional area on the operated side but none showed total atrophy. Less atrophy was present in the patients with a regenerated semitendinosus neotendon compared with those without regeneration (P =.029). In the latter group the semimembranosus muscle seemed to compensate for this with hypertrophy (P =.019). Cross-sectional muscle fiber areas, the relative number of each fiber type and oxidative potential as estimated by citrate synthase activity, showed no significant differences between the operated and nonoperated legs. The isokinetic strength of the hamstrings and quadriceps was significantly lower in the operated leg than in the nonoperated leg.

CONCLUSIONS

With this surgical technique, the semitendinosus muscle can recover and the tendon has, according to the MRI images, a great potential to regenerate after its removal.

Techniques for reducing anterior knee symptoms after anterior cruciate ligament reconstruction using a bone-patellar tendon-bone autograft

Seventy-five patients underwent unilateral anterior cruciate ligament reconstruction with an ipsilateral bone-patellar tendon-bone autograft at our institution. The graft was harvested using a two-transverse-incision technique, and patellar and tibial bony defects were repaired with cored bone grafts collected by reaming the femoral socket and the tibial socket or tunnel. We evaluated the incidence of anterior knee pain, donor site tenderness, and sensory disturbance after use of these procedures. We also analyzed the correlation between anterior knee pain and age, sex, bone plug length, range of motion, postoperative stability, patellar tendon shortening, infrapatellar nerve injury, and the size of the patellar defect. Thirteen patients reported anterior knee pain. Donor site tenderness was detected in 10 patients and was located on the inferior pole of the patella, the tibial tubercle, or both. Sensory disturbance was found over the infrapatellar nerve area in 13 patients. Statistical analysis showed that anterior instability (side-to-side difference of >3 mm) and residual patellar bony defect (depth >2 mm) were risk factors for anterior knee pain. The results of our study suggest that cored cancellous bone grafting for complete restoration of the donor site bony defects and the two-transverse-incision technique to preserve the infrapatellar branch of the saphenous nerve contribute to prevention of anterior knee symptoms.

Magnetic resonance imaging at different time periods following hamstring harvest for anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to evaluate the magnetic resonance imaging (MRI) appearance of the hamstring graft harvest site after harvesting the hamstring tendons to reconstruct a torn anterior cruciate ligament (ACL).

TYPE OF STUDY

Case series.

METHODS

We performed MRI on 21 patients who had previously undergone hamstring harvest and ACL reconstruction. Twenty of the patients (7 female and 13 male; mean age, 37 years; range, 16 to 84 years), all volunteers, were selected from a series of 45 ACL reconstructions performed by the senior author during a 20-month period. Another patient, a 32-year-old man, underwent ACL reconstruction elsewhere 32 months before. Both the semitendinosus and gracilis tendons were harvested in all cases. All MRIs were obtained on a 1.5-T magnet and were prospectively evaluated by 2 experienced musculoskeletal radiologists who were blinded to the time interval between graft harvest and MRI.

RESULTS

Two weeks after graft harvest, MRI showed ill-defined intermediate signal on T1-weighted images and increased signal on T2-weighted images, consistent with fluid in the harvest site, with no discernable tendon. At 6 weeks, structures were seen at the level of the superior pole of the patella that had morphology and signal characteristics similar to native tendon. By 3 months, structures with normal morphology and signal characteristics were seen to the level of the joint line, and by 12 months, to the level of 1 to 3 cm above that of the tibial attachment. At 32 months, the tendons appeared on MRI to normalize to a level of 1 to 2 cm above their tibial attachment.

CONCLUSION

Following hamstring tendon harvest, MRI demonstrates an apparent regeneration of tendons beginning proximally and extending distally over time.