The reharvested central third of the patellar tendon. A histologic and biomechanical analysis

Biomechanical and histological comparison of two suture configurations for soft tissue grafts: speedtrap™ versus krackow stitch

To compare 2 different graft preparation techniques to determine biomechanical strength and resultant tissue trauma evaluated by histology. Twelve common flexors of the finger's tendons were prepared with either tubulization (SpeedTrap™) or transtendon stiches (Orthocord™). The stiffness, resistance and energy at maximum load were tested for biomechanical assessment in both groups. After load testing, Samples were stained with hematoxylin and eosin (HE) to evaluate histological damage. We observe that the time to prepare tendons with SpeedTrap™ was 8.3 times faster (1:25 min) than traditional ones (15:02 min). In all cases, the mean values for SpeedTrap™ were higher in terms of strength, stiffness and energy at maximum load than for traditional suture but without significant difference (p > 0.05). The Krackow stitch produces greater structural damage to the collagen fibers while SpeedTrap™ maintains better organized arrangement of the fibers after tubulization preparation. With the results obtained, we can conclude that the tubulization technique allows faster graft preparation with less structural damage to the manipulated tissue without altering the biomechanical resistance provided by the transtendon suture technique.

Growth-related changes in the ultrastructure of the quadriceps tendon

BACKGROUND

The purpose of this study was to investigate the effect of growth on the ultrastructural characteristics of the quadriceps tendon (QT).

METHODS

Eighteen included patients were classified into three groups based on age and epiphyseal plate condition: the 'immature group' consisted of patients with open epiphyseal plates (11.5 ± 1.6 years old; mean ± standard deviation), the 'young group' consisted of patients aged <20 years with closed epiphyseal plates (15.8 ± 1.0 years), and the 'adult group' consisted of all patients aged >20 years (29.8 ± 11.3 years) irrespective of epiphyseal plate condition. Tendon tissue samples were used for ultrastructural analysis by transmission electron microscopy. Minimum collagen fibril diameters were measured from the cross sections of collagen fibril images using Image J software. The average number of collagen fibers per sample was 797 ± 109, and the average collagen fibril diameter of each sample was compared using one-way analysis of variance.

RESULTS

The mean collagen fibril diameter was 89.7 ± 14.4 nm in the immature group, 94.8 ± 16.4 nm in the young group, and 107.2 ± 12.1 nm in the adult group, with significant differences between the immature and adult groups, and between the young and adult groups (P = 0.001 and P = 0.021, respectively); however, no significant differences were observed between the immature and young adult groups (P = 0.49).

CONCLUSIONS

The collagen fibril diameter of the QT was found to have increased with growth. The study provided insights into graft selection.

Open patellar tendon avulsion from tibial tuberosity after ACL reconstruction successfully treated with suture anchors

Patellar tendon rupture after anterior cruciate ligament (ACL) reconstruction is a rare complication which usually occurs in the early postoperative period during rehabilitation. The management of open avulsions from tibial tuberosity has not been clearly defined yet. We describe a previously unreported case of traumatic and open patellar tendon avulsion from tibial tuberosity one year following ACL reconstruction in an elite football player which was successfully treated with suture anchors. (www.actabiomedica.it)

Sex Differences in the Residual Patellar Tendon After Harvesting Its Central Third for Anterior Cruciate Ligament Reconstruction

OBJECTIVES

Some studies have found that sex can affect the clinical results after anterior cruciate ligament reconstruction. We hypothesized that sex would significantly affect the healing of the postoperative patellar tendon. This study evaluated the patellar tendon after bone-patellar tendon-bone autograft harvest, specifically with regard to sex-dependent differences.

METHODS

At 6 months postoperatively, an ultrasonographic evaluation was performed. We measured the residual donor site gap width between tendon tissues and the thickness of newly formed nontendinous tissue in the gap. In addition, the cross-sectional area of tendon tissue was measured. The ratios between the operated and contralateral sides were calculated, and the sexes were compared. A paired Student t test was performed, with P < .05 considered statistically significant.

RESULTS

The population of 52 patients (32 male and 20 female) had a mean age ± SD of 23 ± 8 years. We observed no significant sex-dependent differences in the residual donor site gap and the thickness of newly formed nontendinous tissue when calculating ratios to the contralateral tendon. The mean cross-sectional area of tendon tissue was 101 ± 26 mm² (male, 114 ± 26 mm² ; female, 80 ± 16 mm² ). When the ratios to the contralateral tendon were calculated, male patients had significantly higher cross-sectional area ratios than female patients (male, 124% ± 20%; female, 100% ± 19%, P = .024).

CONCLUSIONS

We have reported a dramatic increase in the cross-sectional area of patellar tendon tissue during the first 6 months after anterior cruciate ligament reconstruction with a bone-patellar tendon-bone autograft, which was more prominent in male patients than in female patients. This difference might have contributed to the sex-dependent variation in clinical outcomes.

Late quadriceps tendon rupture at the donor site following cruciate ligament reconstruction using central quadriceps tendon graft

Central quadriceps tendon (CQT) graft has been successfully used as a viable autograft option in cruciate ligament reconstruction of the knee. The prime emphasis in the majority of the literature is given to surgical details of quadriceps graft harvesting and outcome of cruciate ligament reconstruction. There is less discussion about donor site morbidity in CQT graft, and it is less frequent as compared to that in bone patellar tendon bone graft. We report an extremely unusual case of late quadriceps tendon rupture at the donor site following anterior cruciate ligament reconstruction using CQT graft.

Regional mechanical properties of human patellar tendon allografts

PURPOSE

Very little is known regarding regional biomechanical properties of patellar tendon allografts.

METHODS

Ten human bone-tendon-bone (BTB) patellar grafts were separated into equal thirds and underwent cyclic and failure testing. Grafts were non-irradiated and processed using proprietary sterilization methods.

RESULTS

The central third was the thickest region (4.9 ± 0.4 mm) compared to the medial and lateral (p < 0.05). The lateral third was the longest region (58.8 ± 8.8 mm) compared to the medial (47.9 ± 8.5 mm) and central (47.2 ± 8.8 mm) portions (p < 0.05). Cyclic testing demonstrated no regional differences with respect to elongation (n.s.) and creep strain (n.s.). Failure testing demonstrated increased maximum load and stiffness in the central region (1,680 ± 418 N and 278 ± 67 N/mm, respectively) as compared to the medial (1,033 ± 214 N, p < 0.002, 201 ± 37 N/mm, p < 0.03) and lateral thirds (908 ± 412 N, p < 0.03, 173 ± 66 N/mm, p < 0.002). Elongation at maximum load did not vary between regions. Central region maximum stress (41.0 ± 12.5 MPa) was greater than that of the medial third (28.1 ± 3.6 MPa, p < 0.02), with strain at maximum stress larger in the central third (0.21 ± 0.03) compared to lateral (0.16 ± 0.03, p < 0.01).

CONCLUSIONS

The central third of a non-irradiated, human bone-patellar tendon-bone construct is thicker and biomechanically superior to the medial and lateral regions in most respects. These findings reinforce the use of the central third of a patellar tendon allograft in anterior cruciate ligament reconstruction. Further investigations are required to determine whether the decreased biomechanical properties of the medial and lateral third of the BTB construct negatively influence the mechanical function of hemi-BTB grafts.

Healing of donor site in bone-tendon-bone ACL reconstruction accelerated with plasma rich in growth factors: a randomized clinical trial

PURPOSE

To determine whether the use of plasma rich in growth factors accelerates healing of the donor site in bone-tendon-bone anterior cruciate ligament (ACL) reconstruction (patellar graft). The use of the patellar graft presents post-operative problems such as anterior knee pain, which limits its use and leads to preference being taken for alternative grafts.

METHODS

A double-blind, randomized, clinical trial was performed comparing two groups of patients who underwent ACL reconstruction using patellar tendon graft and comparing the use of plasma rich in growth factors at the donor site after graft harvest in terms of local regeneration by ultrasound assessment.

RESULTS

The plasma rich in growth factors group shows earlier donor site regeneration in comparison with the control group (2 months earlier), with significant differences in the first 4 months of the follow-up.

CONCLUSION

The application of plasma rich in growth factors shows accelerated tissue regeneration processes with respect to the control group. This fact, together with the previously published with similar conclusions, can create a knowledge basis in order to set out new recovery guidelines following ACL reconstruction.

LEVEL OF EVIDENCE

Therapeutic study, Level I.

Central-third bone-patellar tendon-bone allografts demonstrate superior biomechanical failure characteristics compared with hemi-patellar tendon grafts

BACKGROUND

Reconstruction of the anterior cruciate ligament (ACL) is commonly performed with a bone-patellar tendon-bone (BTB) allograft. However, grafts may result from harvesting the central region of a whole graft (C-BTB), the medial 10 mm of a lateral hemi-BTB (L-BTB) graft, or the lateral 10 mm of a medial hemi-BTB (M-BTB) graft.

PURPOSE

To quantify potential differences in graft biomechanical properties when comparing whole versus hemi-BTB grafts.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten pairs of human BTB allografts (irradiated with 1.0-1.2 Mrad) were randomized to preparation as whole grafts or hemigrafts. From these, 10-mm grafts were prepared from the center or the most central portion, respectively. After measurements of tendon thickness, width, and length, specimens underwent cyclic tensile testing, followed by load-to-failure analysis. Biomechanical outcomes included cyclic elongation and creep strain along with the following failure characteristics: maximum load, elongation at maximum load, maximum stress, strain at maximum stress, and linear stiffness.

RESULTS

Regionally, the mean thickness of the C-BTB (5.18 ± 0.75 mm), M-BTB (5.08 ± 0.56 mm), and L-BTB (5.32 ± 0.62 mm) grafts were comparable (P > .72). Similarly, the mean length of the C-BTB (47.4 ± 6.73 mm), M-BTB (47.0 ± 5.45 mm), and L-BTB (50.7 ± 6.42 mm) grafts were alike (P > .43). While differences in cyclic elongation and strain were not significant, the M-BTB graft tended to elongate more (0.204 ± 0.13 mm; P = .075) and experience greater strain (0.56% ± 0.32%; P = .054) compared with the C-BTB graft (0.09 ± 0.03 mm and 0.23% ± 0.07%, respectively). Load-to-failure testing demonstrated a higher maximum load (2293 ± 531 N) and stiffness (356 ± 46 N/mm) of the C-BTB graft as compared with the M-BTB graft (1575 ± 325 N [P < .007] and 275 ± 37 N/mm [P < .008], respectively) and L-BTB graft (1585 ± 452 N [P < .008] and 277 ± 65 N/mm [P < .009], respectively). No differences were noted with respect to elongation or stress at maximum load among the grafts. Maximum stress in the C-BTB graft (45.4 ± 11.5 MPa) was greater than in the L-BTB graft (29.7 ± 10.6 MPa) (P < .03) and tended to be greater than the M-BTB graft (34.1 ± 6.27 MPa) (P = .087).

CONCLUSION

Biomechanical failure properties (maximum load, stress, and stiffness) of the central portion of a whole BTB graft are superior to those of the medial portion of a lateral hemi-BTB graft and the lateral portion of a medial hemi-BTB graft. However, cyclic loading characteristics did not differ between grafts.

CLINICAL RELEVANCE

Although the true central-third BTB graft is biomechanically superior to hemi-BTB grafts, future studies are necessary to determine if the use of hemigrafts leads to an increased incidence of clinical failure.

Semitendinosus muscle fatty infiltration following tendon harvest in rabbits

The hamstring tendon autograft is one of the most commonly used graft choices in Anterior cruciate ligament (ACL) reconstruction. There are conflicting results regarding postoperative hamstring strength deficits in patients who have had a hamstring graft. The semitendinosus tendon has been shown to regenerate after harvesting for ACL autograft, suggesting that the muscle has the potential to regain normal function. However, no studies have been performed to define the microstructural changes that occur in the semitendinosus muscle after tendon resection. In this study, we hypothesized that fatty infiltration of the semitendinosus muscle after tendon harvest in New Zealand White rabbits increases postoperatively and remains constant or increases during the first year of repair. The semitendinosus tendon was unilaterally detached and harvested from 15 rabbits. Five rabbits were sacrificed at 3-, 6-, and 12-month intervals, and the semitendinosus muscle-tendon units were analyzed. The contralateral unoperated limb served as the control. The gross tendon and muscle dimensions and histologic percentage of fatty infiltration were measured. We found no significant difference in fatty infiltration at any time point between the control muscle and test specimens and that there was no progression of fatty infiltration over time. If these results hold true in humans, natural repair of the hamstring muscle following tendon harvest during ACL autograft reconstruction is not inhibited by fatty infiltration.

Collagen fibre implant for tendon and ligament biological augmentation. In vivo study in an ovine model

PURPOSE

Although most in vitro studies indicate that collagen is a suitable biomaterial for tendon and ligament tissue engineering, in vivo studies of implanted collagen for regeneration of these tissues are still lacking. The objectives of this study were the following: (1) to investigate the regeneration of the central third of the ovine patellar tendon using implants made of an open array of collagen fibres (reconstituted, extruded bovine collagen); and (2) to compare two collagen crosslinking chemistries: carbodiimide and carbodiimide associated with ethyleneglycoldiglycidylether.

METHODS

Forty-eight Welsh Mountain sheep were operated on their right hind leg. The central third of patellar tendon was removed and substituted with carbodiimide (n = 16) and carbodiimide-ethyleneglycoldiglycidylether-crosslinked implants (n = 16). In the control group the defect was left empty (n = 16). The central third of contralateral unoperated tendons was used as positive controls. Half of the sheep in each group were killed at 3- and 6-month time points. After proper dissection, tendon sub-units (medial, central and lateral) were tested to failure (n = 6 for each group), whilst 2 non-dissected samples were used for histology.

RESULTS

Both the implants had significantly lower stress to failure and modulus with respect to native tendon at both 3- and at 6-month time points. The implants did not statistically differ in stress to failure, whilst carbodiimide-crosslinked implants had significantly higher modulus than carbodiimide-ethyleneglycoldiglycidylether-crosslinked implants both at 3 and at 6 months. Histology showed carbodiimide-crosslinked implants to have a better integration with the native tendon than carbodiimide-ethyleneglycoldiglycidylether-crosslinked implants. Carbodiimide-crosslinked implants appeared partially resorbed and showed increased tissue ingrowth with respect to carbodiimide-ethyleneglycoldiglycidylether-crosslinked implants.

CONCLUSIONS

To deliver collagen implants as an open array of fibres allows optimal tendon-implant integration and good ingrowth of regenerated tissue. In the present study the resorption rate of both the examined implants was too low due to the high level of crosslinking. This led to only minor substitution of the implant with regenerated tissue, which in turn produced a low-strength implanted region. Further studies are needed to find the right balance between strength and resorption rate of collagen fibres.

Allograft salvage procedure in multiple-revision anterior cruciate ligament reconstruction

BACKGROUND

Multiple-revision anterior cruciate ligament (ACL) reconstructions represent a surgical challenge due to the presence of previous tunnels, hardware, injuries to the secondary stabilizers, and difficulties in retrieving autologous tendons. An anatomic ACL reconstruction may therefore result in a demanding surgery, thus requiring 2 stages.

PURPOSE

To analyze the efficacy of an over-the-top ACL reconstruction technique plus extra-articular plasty using Achilles or tibialis posterior tendon allograft in restoring knee stability in patients with at least 2 failed previous ACL reconstructions, as well as to evaluate the factors able to affect the final outcome.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

From 2002 to 2008, 24 male athletes with a mean age of 30.8 years underwent surgery. Twenty patients had undergone 2, whereas 4 patients had undergone 3 previous reconstructions. The International Knee Documentation Committee (IKDC) score and KT-2000 arthrometric evaluation were used to measure outcomes at a mean follow-up period of 3.3 years (range, 2-7).

RESULTS

The mean ± SD IKDC subjective score at follow-up was 81.3 ± 14.0. The IKDC objective score was an A or B in 20 patients (83%). Arthrometer side-to-side difference averaged 3.1 ± 1.1 mm. Range of motion was normal or nearly normal in 23 patients and abnormal in 1. Of the 20 good results, 17 patients resumed sports activity at the preinjury level.

CONCLUSION

A 2-stage revision is an accepted option in cases of excessive tunnel enlargement and bone loss, especially on the femoral side, to achieve anatomic reconstruction. Nonanatomic over-the-top ACL reconstruction and lateral extra-articular plasty technique allow one to overcome difficult anatomic situations on the femoral side, permitting a 1-step surgery. The overall results obtained in this series are comparable with those of other ACL revision series. The higher rate of mild instability observed in our series may not be attributable to the surgical technique but rather to the chronic instability suffered by these knees before last revision.

The reharvested patellar tendon has the potential for ligamentization when used for anterior cruciate ligament revision surgery

PURPOSE

The aim of the present study was to make an in-depth clinical, radiographical, and histological evaluation of patients who underwent anterior cruciate ligament (ACL) revision surgery with reharvested central third patellar tendon autograft.

METHODS

Four patients (two women and two men) underwent ACL revision surgery with reharvested patellar tendon autograft 71 (66-120) months after the primary reconstruction. The patients were followed prospectively and underwent a clinical examination and magnetic resonance imaging (MRI) at two and 10 years. Furthermore, they underwent a second-look arthroscopy involving a biopsy procedure from the reconstructed ACL 3 years after revision surgery.

RESULTS

The clinical results were poor both at two and 10 years, but the knees were stable and had a firm endpoint in all four patients in the Lachman test. At the second-look arthroscopy, the graft appeared macroscopically normal in all four patients. Histologically two patients had a normal or close to normal appearance of the reconstructed ACL with no or slight increase in cellularity and vascularity. Two patients had a marked increase in cellularity and vascularity, and the findings revealed that ligamentization was present in all four patients.

CONCLUSIONS

The clinical outcome 10 years after ACL revision surgery was poor in these four patients. In contrast, the reharvested patellar tendon appeared close to normal on MRI, and the second-look arthroscopy with the concomitant histological findings revealed that the grafts were viable 3 years after revision. Therefore, the reharvested patellar tendon seems to have the potential for ligamentization when used for ACL revision surgery.

LEVEL OF EVIDENCE

Case series, Level IV.

The relationships among spatiotemporal collagen gene expression, histology, and biomechanics following full-length injury in the murine patellar tendon

Tendon injuries are major orthopedic problems that worsen as the population ages. Type-I (Col1) and type-II (Col2) collagens play important roles in tendon midsubstance and tendon-to-bone insertion healing, respectively. Using double transgenic mice, this study aims to spatiotemporally monitor Col1 and Col2 gene expression, histology, and biomechanics up to 8 weeks following a full-length patellar tendon injury. Gene expression and histology were analyzed weekly for up to 5 weeks while mechanical properties were measured at 1, 2, 5, and 8 weeks. At week 1, the healing region displayed loose granulation tissue with little Col1 expression. Col1 expression peaked at 2 weeks, but the ECM was highly disorganized and hypercellular. By 3 weeks, Col1 expression had reduced and by 5 weeks, the ECM was generally aligned along the tendon axis. Col2 expression was not seen in the healing midsubstance or insertion at any time point. The biomechanics of the healing tissue was inadequate at all time points, achieving ultimate loads and stiffnesses of 48% and 63% of normal values by 8 weeks. Future studies will further characterize the cells within the healing midsubstance and insertion using tenogenic markers and compare these results to those of tendon cells during normal development.

Human patellar tendon stiffness is restored following graft harvest for anterior cruciate ligament surgery

Minimising post-operative donor site morbidity is an important consideration when selecting a graft for surgical reconstruction of the torn anterior cruciate ligament (ACL). One of the most common procedures, the bone-patellar tendon-bone (BPTB) graft involves removal of the central third from the tendon. However, it is unknown whether the mechanical properties of the donor site (patellar tendon) recover. The present study investigated the mechanical properties of the human patellar tendon in 12 males (mean+/-S.D. age: 37+/-14 years) who had undergone surgical reconstruction of the ACL using a BPTB graft between 1 and 10 years before the study (operated knee; OP). The uninjured contralateral knee served as a control (CTRL). Patellar tendon mechanical properties were assessed in vivo combining dynamometry with ultrasound imaging. Patellar tendon stiffness was calculated from the gradient of the tendon's force-elongation curve. Tendon stiffness was normalised to the tendon's dimensions to obtain the tendon's Young's modulus. Cross-sectional area (CSA) of OP patellar tendons was larger by 21% than CTRL tendons (P<0.01). Patellar tendon stiffness was not significantly different between OP and CTRL tendons, but the Young's modulus was lower by 24% in OP tendons (P<0.01). A compensatory enlargement of the patellar tendon CSA, presumably due to scar tissue formation, enabled a recovery of tendon stiffness in the OP tendons. The newly formed tendon tissue had inferior properties as indicated by the reduced tendon Young's modulus, but it increased to a level that enabled recovery of tendon stiffness.

Comparative and morphological analysis of commonly used autografts for anterior cruciate ligament reconstruction with the native ACL: an electron, microscopic and morphologic study

Ligaments and tendons are similar in composition but differ in proportion and arrangement. Tendons are being used as grafts for the ACL reconstruction. Their microscopic structure has not been sufficiently studied and compared to the native ACL. A null hypothesis was declared stating that the anterior cruciate ligament should be histological, morphologically and functionally different from the tendon grafts used for ACL reconstruction. We investigated similarities and differences of the structure of ACL and tendons used as a graft tissue for ACL reconstruction. In this study, standardized samples of quadriceps, hamstrings (semitendinosus and gracilis) and patellar tendons, and the ACL were harvested from 26 autopsies (average age 36.4) and were investigated using light and electron microscopy, immunohistochemistry and morphometry. The thickness of the collagen fibrils, collagen organization and diameter, the fibril/interstitium ratio, density of fibroblasts and blood vessels, and distribution of the collagen type I, III and V fibrils were analyzed. The semitendinosus showed the highest density of fibroblasts and blood vessels, while the gracilis the highest fibril/interstitium ratio. No differences regarding the thickness of collagen fibrils and distribution of fibrils were found. The ACL had the highest concentration of type III and V collagen fibrils as well as elastic fibers. The histological and ultrastructural appearance of the ACL differs from those of the tendons used as graft, for ACL reconstruction. Its ultrastructure is varied and complex, with its collagen fibers bundles lying in many directions.

A histological and ultrastructural evaluation of the patellar tendon 10 years after reharvesting its central third

PURPOSE

This study was undertaken to evaluate the histologic and ultrastructural characteristics of the patellar tendon 10 years after reharvesting its central third.

HYPOTHESIS

In the long term, after its central third is reharvested, the patellar tendon does not regain a normal histological and ultrastructural appearance.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Twelve consecutive patients (4 women, 8 men) who underwent anterior cruciate ligament revision surgery using reharvested ipsilateral patellar tendon autografts were included in the study. Percutaneous biopsy samples were obtained from the central and lateral parts of the patellar tendon under ultrasonographic guidance at a median of 116 months (range, 102-127 months) after the revision procedure. Eleven biopsy specimens from asymptomatic patellar tendons obtained from open anterior cruciate ligament reconstructions served as controls. The histologic characteristics and the presence of glycosaminoglycans were assessed using a light microscope, and the ultrastructure was assessed using a transmission electron microscope.

RESULTS

The histological evaluation revealed deterioration in fiber structure, increased cellularity, and increased vascularity in both the central and peripheral parts of the reharvested patellar tendon specimens compared with normal tendon specimens. No difference in the amount of glycosaminoglycans was seen in specimens from either part of the reharvested patellar tendons and the control specimens. The ultrastructural evaluation revealed that all the control specimens had a normal morphologic appearance and a compact extracellular matrix with regularly oriented collagen fibrils. Furthermore, in the control specimens, the fibril diameter was heterogeneous, with all fibril size classes present. Specimens from the central and the lateral part of the reharvested tendon displayed pathological cell appearance and a more heterogeneous extracellular matrix. The lateral specimens from the reharvested tendons also displayed all fibril size classes but with a more homogeneous distribution. In the central specimens, the largest fibril size class was absent.

CONCLUSION

Ten years after its central third was reharvested for anterior cruciate ligament revision surgery, the patellar tendon had not normalized in terms of its histological and ultrastructural appearance.

Ultrastructural collagen fibril alterations in the patellar tendon 6 years after harvesting its central third

BACKGROUND

Clinically, donor site problems are common, even in the long term after anterior cruciate ligament reconstruction using patellar tendon autograft. However, there is a lack of knowledge in terms of the mid- and long-term ultrastructural appearance of the previously harvested tendon in humans.

HYPOTHESIS

The patellar tendon does not regain normal ultrastructure 6 years after harvesting its central third and leaving the defect open.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Thirteen patients were included in the study. Biopsy specimens were obtained from the central and lateral thirds of the patellar tendon under ultrasound guidance 71 months (range, 68-73 months) after the reconstruction. Ten biopsy specimens from other subjects with asymptomatic patellar tendons served as controls. The sections were evaluated using transmission electron microscopy. Longitudinal sections were used for morphological evaluation, and the fibril diameter was measured on the transverse sections and grouped into 5 diameter classes.

RESULTS

All control specimens were found to have a compact extracellular matrix with regularly oriented collagen fibrils. Specimens from the lateral part of the harvested tendons displayed a more heterogeneous extracellular matrix. In 3 specimens, the extracellular matrix was different from that of the control specimens. Specimens from the central part of the harvested tendons displayed an even more heterogeneous extracellular matrix, with 8 specimens judged as heterogeneous. The fibril diameter in control specimens displayed the most heterogeneous pattern, and all 5 fibril classes were present. All fibril classes were found in the lateral biopsy specimens from the previously harvested tendons, but the 2 smallest fibril classes (0-30 and 31-60 nm) were significantly more dominant compared with control specimens (P < .0001). In the central specimens from the previously harvested tendons, only the 3 smallest size classes were found (P < .0001 vs controls).

CONCLUSION

Six years after harvesting its central third and leaving the defect open, the patellar tendon revealed a "more heterogeneous matrix" with changes in ultrastructural morphology and relative fibril diameter distribution compared with normal control tendon.

The course of the patellar tendon after reharvesting its central third for ACL revision surgery: a long-term clinical and radiographic study

The choice of the optimal graft for anterior cruciate ligament (ACL) revision surgery is still controversial. Reharvesting the patellar tendon has been suggested as one graft alternative. Our hypothesis was that in the long-term, ACL revision surgery using reharvested patellar tendon autografts would render a good clinical outcome and a normal patellar tendon at the donor site as seen on magnetic resonance imaging (MRI). Fourteen consecutive patients (five women, nine men), who underwent ACL revision surgery using reharvested ipsilateral patellar tendon grafts, were included in the study. They underwent bilateral MRI evaluations of the patellar tendon and were tested for clinical outcome 26 (20-35) and 115 months (102-127) after the revision procedure. On the second occasion, they also underwent standard weight-bearing X-ray examinations. The serial MRI evaluations revealed that the thickness of the patellar tendon at the donor site was significantly increased compared with the non-harvested, normal contralateral side and that the donor-site gap was still visible after 10 years. No significant differences were seen between the 2- and 10-year MRI evaluations. Standard weight-bearing X-ray examinations revealed signs of mild degenerative changes in all patients. Clinical results in terms of the Lysholm score, IKDC evaluation system, one-leg-hop test, KT-1000 laxity test and the knee-walking test revealed no significant differences between the 2- and 10-year assessments. In overall terms, the clinical results were considered to be poor on both occasions. The patellar tendon at the donor site had not normalised 10 years after the reharvesting procedure, as seen on MRI. Furthermore, the clinical results were poor after ACL revision surgery using reharvested patellar tendon autograft.

Regeneration of the hamstring tendons after harvesting for arthroscopic anterior cruciate ligament reconstruction: a histological study in 11 patients

The purpose of our study is to evaluate whether the hamstring tendons can regrow after harvesting for anterior cruciate ligament (ACL) reconstruction and whether the regenerate tissue can be histologically characterized as tendinous. Eleven of the patients (eight female and three male; mean age, 23 years; range 17-37 years) consented to participate in this study. One year after the ACL reconstruction, surgical biopsy was done. Regeneration of the tendon was detected macroscopically in 9 of the 11 patients. Histologically and immunohistochemically, the regenerated tendons closely resembled normal ones. The results of this study show the hamstring tendons can regenerate after harvesting for the ACL reconstruction.

Revision anterior cruciate ligament reconstruction with quadriceps tendon-patellar bone autograft

PURPOSE

To evaluate the cause of recurrent pathologic instability after anterior cruciate ligament (ACL) surgery and the effectiveness of revision reconstruction using a quadriceps tendon autograft using a 2-incision technique.

TYPE OF STUDY

Retrospective follow-up study.

METHODS

Between 1999 and 2001, 31 patients underwent ACL revision reconstruction because of recurrent pathologic instability during sports or daily activities. Twenty-eight patients were reviewed after a mean follow-up of 4.2 years (range, 3.3 to 5.6 years). The mean age at revision surgery was 27 years (range, 18 to 41 years). The average time from primary procedure to revision surgery was 26 months (range, 9 to 45 months). A clinical, functional, and radiographic evaluation was performed. Also magnetic resonance imaging (MRI) or computed tomography (CT) scanning was performed. The International Knee Documentation Committee (IKDC), Lysholm, and Tegner scales were used. A KT-1000 arthrometer measurement (MEDmetric, San Diego, CA) by an experienced physician was made.

RESULTS

Of the failures, 79% had radiographic evidence of malposition of their tunnels. In only 6 cases (21%) was the radiologic anatomy of tunnel placement judged to be correct on both the femoral and tibial side. The MRI or CT showed, in 6 cases, a too-centrally placed femoral tunnel. After revision surgery, the position of tunnels was corrected. A significant improvement of Lachman and pivot-shift phenomenon was observed. In particular, 17 patients had a negative Lachman test, and 11 patients had a grade I Lachman with a firm end point. Preoperatively, the pivot-shift test was positive in all cases, and at last follow-up in 7 patients (25%) a grade 1+ was found. Postoperatively, KT-1000 testing showed a mean manual maximum translation of 8.6 mm (SD, 2.34) for the affected knee; 97% of patients had a maximum manual side-to-side translation <5 mm. At the final postoperative evaluation, 26 patients (93%) graded their knees as normal or nearly normal according to the IKDC score. The mean Lysholm score was 93.6 (SD, 8.77) and the mean Tegner activity score was 6.1 (SD, 1.37). No patient required further revision. Five patients (18%) complained of hypersensitive scars from the reconstructive surgery that made kneeling difficult.

CONCLUSIONS

There were satisfactory results after ACL revision surgery using quadriceps tendon and a 2-incision technique at a minimum 3 years' follow-up; 93% of patients returned to sports activities.

LEVEL OF EVIDENCE

Level IV, case series, no control group.

A long-term serial histological evaluation of the patellar tendon in humans after harvesting its central third

It is previously known that the patellar tendon does not normalise histologically in the short term after harvesting its central third. The aim of the study was to obtain long-term serial biopsies from the central and peripheral parts of the patellar tendon after the harvesting procedure. Our hypothesis was that in the long term after harvesting its central third, the patellar tendon does not regain normal histological appearance. Seventeen consecutive patients, who had undergone anterior cruciate ligament reconstruction using patellar tendon autografts, were included. Percutaneous biopsies were obtained under ultrasonographic guidance 27 (24-29) months and 71 (68-73) months after the index procedure, respectively. The sections were stained with haematoxylin and eosin. The biopsies were evaluated using light microscope. Both at 27 months and 71 months, the fibre structure was deteriorated and the vascularity and cellularity were increased compared with normal tendon. This was seen in both the central and peripheral parts of the tendon. In conclusion, nearly 6 years after harvesting its central third, the patellar tendon had still not normalised histologically, neither in the central nor peripheral parts of the tendon.

Graft selection in anterior cruciate ligament reconstruction

The ideal graft for use in anterior cruciate ligament reconstruction should have structural and biomechanical properties similar to those of the native ligament, permit secure fixation and rapid biologic incorporation, and limit donor site morbidity. Many options have been clinically successful, but the ideal graft remains controversial. Graft choice depends on surgeon experience and preference, tissue availability, patient activity level, comorbidities, prior surgery, and patient preference. Patellar tendon autograft, the most widely used graft source, appears to be associated with an increased incidence of anterior knee pain compared with hamstring autograft. Use of hamstring autograft is increasing. Quadriceps tendon autograft is less popular but has shown excellent clinical results with low morbidity. Improved sterilization techniques have led to increased safety and availability of allograft, although allografts have a slower rate of incorporation than do most types of autograft. No graft has clearly been shown to provide a faster return to play. However, in general, patellar tendon autografts are preferable for high-performance athletes, and hamstring autografts and allografts have some relative advantages for lower-demand individuals. No current indications exist for synthetic ligaments.

Collagen fibril diameter distribution does not reflect changes in the mechanical properties of in vitro stress-deprived tendons

The purpose of this study was to determine if an association exists between the tensile properties and the collagen fibril diameter distribution in in vitro stress-deprived rat tail tendons. Rat tail tendons were paired into two groups of 21 day stress-deprived and 0 time controls and compared using transmission electron microscopy (n = 6) to measure collagen fibril diameter distribution and density, and mechanical testing (n =6) to determine ultimate stress and tensile modulus. There was a statistically significant decrease in both ultimate tensile strength (control: 17.95+/-3.99 MPa, stress-deprived: 6.79+/-3.91 MPa) and tensile modulus (control: 312.8+/-89.5 MPa, stress-deprived: 176.0+/-52.7 MPa) in the in vitro stress-deprived tendons compared to controls. However, there was no significant difference between control and stress-deprived tendons in the number of fibrils per tendon counted, mean fibril diameter, mean fibril density, or fibril size distribution. The results of this study demonstrate that the decrease in mechanical properties observed in in vitro stress-deprived rat tail tendons is not correlated with the collagen fibril diameter distribution and, therefore, the collagen fibril diameter distribution does not, by itself, dictate the decrease in mechanical properties observed in in vitro stress-deprived rat tail tendons.

Evaluation of hamstring strength and tendon regrowth after harvesting for anterior cruciate ligament reconstruction

BACKGROUND

It is generally thought that tissue regeneration and good functional recovery can be expected after anterior cruciate ligament reconstruction using the hamstring tendons. However, persistent strength deficit in deep knee flexion has also been reported.

HYPOTHESIS

Morphologic regeneration of the harvested hamstring tendon is not necessarily associated with its functional recovery.

STUDY DESIGN

Retrospective follow-up study.

METHOD

Twenty-eight patients who underwent anterior cruciate ligament reconstruction with hamstring graft were evaluated after a minimum period of 2 years. Status of tendon regrowth was assessed by magnetic resonance imaging. To specifically analyze the functional deficit after graft harvest, the isometric hamstring strength was examined in a sitting position at 90 degrees of flexion and a prone position at 90 degrees and 110 degrees of flexion. Then, the strength data were correlated with the extent of tendon regeneration.

RESULTS

In 22 of the 28 patients, a regrowth of the semitendinosus tendon was found, whereas regeneration of the gracilis tendon was observed in 13 patients. In the evaluation of hamstring strength, the isometric peak torque was reduced to 86.2%, 54.6%, and 49.1%, respectively, in the aforementioned 3 postures as compared with the contralateral side.

CONCLUSIONS

Significant functional deficit of hamstring strength remains regardless of morphologic regeneration.

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.

Revision anterior cruciate ligament reconstruction using the regenerated semitendinosus tendon: analysis of ultrastructure of the regenerated tendon

In this report, we present a case of a college skier who sustained a rerupture of the reconstructed anterior cruciate ligament (ACL) 8 months after surgery in which an autogenous semitendinosus tendon graft was used. At the revision surgery, the harvested semitendinosus tendon appeared to be regrown. Thus the regenerated tendon was reharvested, and in combination with the gracilis tendon, was used as a graft. The electron microscopic examination revealed a difference in fibril diameter between the regenerated tissue and the normal tendon. Although the regenerated semitendinosus tendon could be reharvested, the feasibility of its use for revision surgery is still to be determined.

Revision anterior cruciate ligament reconstruction

Revision ACL surgery is indicated in patients who present with pathologic anterior laxity on clinical examination that reproduces their symptoms of instability during activities of daily living or athletic activities. The goals of the revision ACL surgery are to stabilize the knee, prevent further injury to the articular cartilage and menisci, and maximize the patient's function. Successful revision ACL surgery requires a thorough preoperative evaluation, including a detailed history, physical examination, and radiographic evaluation. Preoperative planning begins with a determination of the mechanisms of failure for the initial ACL reconstruction. Often a primary, as well as secondary cause, for failure can be identified. The determination of the cause of failure is the first step in a carefully-constructed treatment plan, which includes consideration of skin incisions to be used, method of graft removal, hardware removal, the need for a staged procedure or concomitant surgery, graft material selection, tunnel placement, graft fixation, and postoperative rehabilitation protocol. Despite the most meticulous planning, unanticipated findings may be encountered in the operating room, and the preoperative plan should have enough flexibility to accommodate these developments. Finally, it is crucial to counsel the patient preoperatively to limit his or her expectations regarding their surgical outcome. Given the complexity of revision ACL reconstruction, patient expectations must be adjusted to realistically match the potential for success. With proper planning, attention to detail, and appropriate patient expectations, revision ACL surgery can result in a beneficial and satisfying patient outcome.

Anterior cruciate ligament reconstruction with a reharvested bone-patellar tendon-bone graft

We sought to determine the results in patients who underwent revision anterior cruciate ligament reconstruction with a reharvested bone-patellar tendon-bone graft. Preoperative magnetic resonance imaging of the patellar tendon was used to determine the width of the tendon and the quality of the tissue. The section of the tendon harvested included 7 to 8 mm of the regenerated tendon and 2 to 3 mm of previously untouched tendon either medial or lateral to the healed tissue. The mean time from primary graft harvest to reharvest was 71.0 +/- 44 months (range, 32 to 180). An accelerated rehabilitation program was used postoperatively. Objective follow-up of more than 2 years after surgery was available for 8 patients at a mean of 49.0 +/- 15.4 months. The average range of motion in the anterior cruciate ligament-reconstructed knee was 6/0/133 at 1 month postoperatively and 6/0/145 at long-term follow-up. The mean manual maximum KT-1000 arthrometer difference between knees was 1.6 +/- 1.2 mm. The mean isokinetic quadriceps muscle strength of the reharvested graft donor knee was 103% +/- 7% of that of the opposite knee. Subjective scores were obtained from 11 patients (12 knees) at a mean of 51.5 +/- 35.7 months (range, 24 to 150) after surgery; the mean score was 89.3 +/- 6.9 points. We conclude that with appropriate preoperative planning, a reharvested patellar tendon can be used for revision anterior cruciate ligament reconstruction to obtain reliable stability and strength postoperatively.

Donor-site morbidity and anterior knee problems after anterior cruciate ligament reconstruction using autografts

The authors review the current knowledge on donor site-related problems after using different types of autografts for anterior cruciate ligament (ACL) reconstruction and make recommendations on minimizing late donor-site problems. Postoperative donor-site morbidity and anterior knee pain following ACL surgery may result in substantial impairment for patients. The selection of graft, surgical technique, and rehabilitation program can affect the severity of pain that patients experience. The loss or disturbance of anterior sensitivity caused by intraoperative injury to the infrapatellar nerve(s) in conjunction with patellar tendon harvest is correlated with donor-site discomfort and an inability to kneel and knee-walk. The patellar tendon at the donor site has significant clinical, radiographic, and histologic abnormalities 2 years after harvest of its central third. Donor-site discomfort correlates poorly with radiographic and histologic findings after the use of patellar tendon autografts. The use of hamstring tendon autografts appears to cause less postoperative donor-site morbidity and anterior knee problems than the use of patellar tendon autografts. There also appears to be a regrowth of the hamstring tendons within 2 years of the harvesting procedure. There is little known about the effect on the donor site of harvesting fascia lata and quadriceps tendon autografts. Efforts should be made to spare the infrapatellar nerve(s) during ACL reconstruction using patellar tendon autografts. Reharvesting the patellar tendon cannot be recommended due to significant clinical, radiographic, and histologic abnormalities 2 years after harvesting its central third. It is important to regain full range of motion and strength after the use of any type of autograft to avoid future anterior knee problems. If randomized controlled trials show that the long-term laxity measurements following ACL reconstruction using hamstring tendon autografts are equal to those of patellar tendon autografts, we recommend the use of hamstring tendon autografts because there are fewer donor-site problems.

Revision anterior cruciate ligament reconstruction with a reharvested ipsilateral patellar tendon

The patellar tendon remains the most popular graft choice for anterior cruciate ligament reconstruction and has been proven to be the strongest substitute. Between 1991 and 1998, we performed revision anterior cruciate ligament reconstruction using the reharvested central third of the ipsilateral patellar tendon in 15 patients. Adequate follow-up was obtained in 13 of these 15 patients. The results in these 13 patients (mean age, 27.2 years) were reviewed. At an average postoperative follow-up of 39.4 months (range, 24 to 65), 11 patients had good or excellent results and 2 patients had fair results. Clinical examination revealed an average Tegner knee score of 5.8 (range, 3 to 9) and an average Lysholm knee score of 77.6 (range, 61 to 98). Postoperative KT-1000 arthrometer results showed an average side-to-side difference of 1.92 mm (range, -2.0 to 4.0). No patient demonstrated any loss of range of motion and only one reported patellofemoral problems, which were moderate. These favorable results demonstrate that, with appropriate patient selection, the use of a reharvested central third patellar tendon is a viable option for revision of a failed anterior cruciate ligament reconstruction.

Revision anterior cruciate surgery with use of bone-patellar tendon-bone autogenous grafts

BACKGROUND

A prospective study was done to determine the functional results, patient satisfaction, and graft failure rate after fifty-seven consecutive revision replacements of the anterior cruciate ligament with use of a bone-patellar tendon-bone autogenous graft.

METHODS

Fifty-four patients (fifty-five operations) were followed in this study. Concurrent operative procedures were performed during the revision procedure in thirty-seven knees (67%). These procedures included repair of a meniscal tear in twenty knees (36%) and reconstruction of deficient posterolateral or medial ligament structures in seventeen knees (31%). Nine knees (16%) had a high tibial osteotomy to correct varus malalignment before the revision operation. The results were evaluated with the Cincinnati Knee Rating System.

RESULTS

There were significant improvements in the scores for pain (p < 0.0001), activities of daily living (p < 0.01), sports participation (p < 0.001), patient satisfaction (p < 0.0001), and overall rating of the knee (p < 0.0001). Thirty-three (60%) of the replaced ligaments were functional, nine (16%) were partially functional, and thirteen (24%) had failed.

CONCLUSIONS

Many knees (93%) had compounding problems, including articular cartilage damage, prior meniscectomy, loss of secondary ligament restraints, varus malalignment, and concomitant ligament replacement or meniscal repair. Therefore, the results were generally less favorable than those following primary operations. The rate of graft failure was three times higher than our previously reported failure rate after primary replacements of the anterior cruciate ligament with a bone-patellar tendon-bone autogenous graft. Even so, symptoms and functional limitations with regard to daily and sports activities were found to have decreased and patient satisfaction improved. We advocate correction of varus malalignment prior to anterior cruciate procedures. Associated posterolateral ligament deficiencies should be surgically corrected during anterior cruciate procedures to prevent excessive loading on the graft from abnormal lateral tibiofemoral joint opening. Meniscal tears, including complex tears that extend into the avascular zone, can be concurrently repaired successfully during the revision.

Patellar tendon rupture 3 years after anterior cruciate ligament reconstruction with a central one third bone-patellar tendon-bone graft

Use of the central one third bone-patellar tendon-bone autograft is an accepted technique for anterior cruciate ligament (ACL) reconstruction. Patellar tendon rupture following ACL reconstruction is an acknowledged, although rarely reported, complication of this procedure. Of the limited patellar tendon rupture cases reported in the literature, most are described early in the postoperative period. We present a case of late patellar tendon rupture more than 3 years after uneventful ACL reconstruction in a 32-year-old man.

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.

A radiographic and histologic evaluation of the patellar tendon after harvesting its central third

Nineteen consecutive patients undergoing anterior cruciate ligament reconstruction using the central third of the ipsilateral patellar tendon were included in the study. Serial magnetic resonance images revealed that the donor-site gap in the tendon decreased with time (mean follow-up, 26 months). The thickness was significantly increased compared with the intact contralateral patellar tendon, regardless of when the magnetic resonance imaging was performed. Ultrasonography showed the same findings at a mean follow-up of 26 months. Histologic evaluation of the repair tissue in the central part of the tendon, as well as the tissue in the peripheral part of the patellar tendon at the donor site, revealed a significant increase in cellularity and vascularity as compared with normal control tendons. Thus, 2 years after the harvesting procedure, the patellar tendon displayed significant radiographic and histologic abnormalities. On the basis of these findings, reharvest of the patellar tendon, at least up to 2 years after primary harvest, cannot be recommended.

Lower limb stability with ACL impairment

STUDY DESIGN

Repeated measures (3 separate day sessions) to determine test reliability; single-session repeated measures to compare stability between limbs.

OBJECTIVES

To develop a functional test measuring dynamic stability that is capable of differentiating between the injured and uninjured lower limb in 2 populations: (1) people with anterior cruciate ligament deficiency (ACLd) and (2) people with anterior cruciate ligament reconstruction (ACLr), and to establish the reliability of this test.

BACKGROUND

Many functional tests of the lower limb used by clinicians, such as the 1-legged hop for distance, the 1-legged hop for time, the vertical jump, the triple hop for distance, shuttle run, and single-limb standing, do not allow the clinician to discern differences between function in the injured and uninjured limbs.

METHODS AND MEASURES

Twenty-five nonimpaired subjects (14 men, 11 women, aged 31.2 +/- 9.1 years), 11 subjects with ACLr (9 men, 2 women, aged 26.3 +/- 10.4 years), and 13 subjects with ACLd (5 men, 8 women, aged 40.4 +/- 12.6 years) were tested. Twelve nonimpaired subjects participated in 3 testing sessions to determine the reliability of the force plate measures. Ground reaction forces (vertical, medial-lateral, and anterior-posterior) were measured while the subjects performed 1-legged hop and step-down tests onto a force plate. Stability was defined as the ability to transfer the vertical projection of the center of gravity to the supporting base and keep the knee still. A repeated-measures analysis of variance (2-factor; limbs by trials) was used to compare the stability between limbs.

RESULTS

The majority of the measures used to calculate dynamic stability were reliable. Moreover, the data provide normal standards of functional knee stability for step-down and hop tests. In the step-down test, changes in vertical force did identify dysfunction in the injured limb (stabilization time = 1527 +/- 216 ms) compared to the uninjured limb (stabilization time = 892 +/- 498 ms) for subjects with ACLr.

CONCLUSIONS

The normal standards may serve as a reference for comparing functional differences in ACLr or ACLd populations. The vertical force parameter during a step-down may be useful as an outcome measure to monitor progress during rehabilitation.

Revision anterior cruciate ligament surgery

An increasing number of revision ACL reconstructions are being performed each year. Revision ACL surgery is challenging and cannot be approached in the same manner as primary ACL surgery. Successful revision ACL surgery requires a detailed history, a comprehensive physical examination, appropriate radiologic studies, and careful preoperative planning. The results of revision ACL surgery do not equal the results of primary ACL surgery, and this should be explained to the patient prior to surgery. In order to avoid repeating errors that led to failure of the primary reconstruction, the etiology of the primary failure must be clearly understood before proceeding with the revision procedure. Although graft failure is the most common reason for failure of the original reconstruction and revision surgery, other non-graft-related problems, such as loss of motion, extensor mechanism dysfunction, and degenerative arthritis, can also result in an unsatisfactory outcome and residual complaints. Errors in surgical technique, specifically nonanatomic graft placement and failure to address associated ligamentous injuries at the time of the original procedure, are responsible for graft failures in most reported series. Preoperative planning must address the issues of graft selection, skin incisions, hardware removal, tunnel placement, graft fixation, and associated ligamentous injuries. Loss of motion and in some cases enlarged bone tunnels may require a staged approach. Because of the weaker initial graft fixation, laxity of secondary restraints, the potential need to address associated ligamentous injuries, and the presence of more significant articular cartilage changes, an accelerated rehabilitation program is inappropriate in most revision cases. Successful revision ACL surgery requires a motivated and compliant patient, a well thought out plan, and an experienced surgeon who is knowledgeable and proficient with a variety of different surgical techniques, graft sources, and graft fixation techniques.