Acute patellar tendon rupture: A new surgical technique

Summary: The most common method used in the treatment of acute patellar tendon ruptures is primary end-to-end repair. The use of the Acufex ACL guide (Acufex Microsurgical, Mansfield, MA) provides efficient and accurate placement of transosseous drill holes in the patella and minimizes the risk, tourniquet time, and surgical time of acute patellar tendon repairs.Arthroscopy: The Journal of Arthroscopic and Related surgery, Vol 16, No 8 (November-December), 2000: pp 869–870     

Reconstruction of the anterior cruciate ligament in females

Purpose: To compare the clinical results of anterior cruciate ligament reconstruction in female patients using quadruple-looped hamstring autograft versus patellar tendon autograft at minimum 2-year follow-up. Type of Study: Case series. Methods: A prospective clinical review was performed to compare the results of ACL reconstruction with hamstring versus patellar tendon autograft in a group of female patients. Exclusion criteria included chronic injuries (greater than 3 months), associated collateral ligament injuries, Workers’ Compensation or litigation cases, and bilateral anterior cruciate ligament injuries. There were 39 female patients in the hamstring group (average follow-up, 40.9 months) and 37 female patients in the patellar tendon group (average follow-up, 52 months). Both types of grafts were fixed with an EndoButton proximally and with sutures tied over a post or button distally. The postoperative rehabilitation regimen was identical for both groups. Objective parameters evaluated included preinjury and postoperative Tegner and Lysholm scores, side-to-side KT-1000 maximum-manual arthrometer differences, and clinical examination including Lachman and pivot-shift tests. Graft failure was defined by any one of the following: a KT-1000 difference of greater than 5 mm, a 2+ Lachman, a 1+ or greater pivot shift, or revision surgery. Results: The failure rate in the hamstring group was 23% versus 8% in the patellar tendon group, which was not statistically significant (P > .1). Comparison of preinjury Tegner activity scores to postoperative scores revealed that patients in the hamstring group did not return to their preinjury level of activity (preinjury 6.54 v postoperative 5.17) as well as patients in the patellar tendon group (preinjury 6.20 v postoperative 6.59). Patients in the hamstring group had a significant increase in pain compared with the patellar tendon group (P = .034). Conclusions: Although not statistically significant, the hamstring group had more failures, more laxity on clinical examination, and more patients with larger KT-1000 arthrometer differences. These results indicate a trend toward increased graft laxity in female patients undergoing reconstruction with hamstring autograft compared with patellar tendon when evaluated by a single surgeon using similar fixation techniques at short- to medium-range follow-up. More studies with larger patient numbers using current fixation techniques are necessary to confirm these findings.     

Biomechanical comparison of quadriceps tendon fixation with patellar tendon bone plug interference fixation in cruciate ligament reconstruction

Purpose: The purpose of this study was to use current fixation techniques and compare the stiffness and ultimate tensile failure of the tendinous end of the quadriceps tendon (QT) with the bone plug end of the bone–patellar tendon–bone (BPTB) graft using current techniques of fixation. Type of Study: Randomized trial of elderly cadaver knees. Materials and Methods: Tibial and femoral biodegradable interference fixation and femoral EndoButton (Smith & Nephew, Acufex, Mansfield, MA) fixation in bone tunnels with the QT and the BPTB graft were compared by using 10 pairs of elderly cadavers and biomechanical testing. Two groups, fixation at time zero (simulating fixation in the operating room) and testing after 1,000 loading cycles (simulating patient rehabilitation exercises), were used. Results: At time zero fixation, stiffness of the soft tissue QT tibial tunnel interference fixation was 59% less stiff than the stiffness of the interference fixation of a BPTB plug in a femoral tunnel (P = .11). The EndoButton femoral fixation resulted in a decrease in stiffness at time zero compared with femoral tunnel interference fixation of the soft tissue QT (P = .03). All groups improved stiffness with cycling the construct to 1,000 cycles. Conclusions: Placement of the QT tendinous end of the graft in the femoral bone tunnel when using a interference fixation will approximate the stiffness of a bone plug in the tibial bone tunnel with interference fixation. The EndoButton fixation is not as stiff as either of the femoral interference fixation options. The addition of more than 20 loading cycles could remove laxity from the graft fixation–graft cruciate ligament complex and improve its stiffness.     

The effect of Workers’ Compensation on clinical outcomes of arthroscopic-assisted autogenous patellar tendon anterior cruciate ligament reconstruction in an acute population

Purpose: To assess the effect of Workers’ Compensation (WC) benefits on subjective outcomes of patients following anterior cruciate ligament (ACL) reconstruction. Type of Study: Prospective study of ACL reconstruction with bone–patellar tendon–bone in an acute population. Methods: From October 1991 through June 1997, 1,015 patients underwent ACL reconstruction, 769 with bone–patellar tendon–bone autografts; 235 met the criteria for this study. All chronic injuries, failed and/or bilateral reconstructions were excluded making the total population 139. The final populations included 115 patients in a non-WC group and 24 patients in a WC group. Average follow-up for was 34.5 months for the WC group and 33.6 months for the non-WC group. All patients had equal objective evaluations, which allowed the subjective criteria to be analyzed. Results: The results revealed a significant difference in the subjective data of patients with WC benefits. Uniformly, WC patients rated subjective criteria as far worse than the non-WC group in postoperative stages. The average of the 15-item visual analog scale showed statistically significant (P <.01) differences between the WC and non-WC groups. Average postoperative Tegner scores were 3.05 for the WC group and 6.02 for the non-WC group, which was statistically significant. The WC group did not return to their preinjury Tegner score. Conclusions: The data show that the patients’ perception of their knee function drastically differs from the objective findings on examination; therefore, it should be anticipated that the WC patient might have lower subjective outcomes from surgical treatment when compared with their non-WC counterparts.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 2 (February), 2001: pp 132–137     

Distal femoral extension osteotomy and patellar tendon advancement or shortening in ambulatory children with cerebral palsy: A modified Delphi consensus study and literature review

Purpose:In children with cerebral palsy, flexion deformities of the knee can be treated with a distal femoral extension osteotomy combined with either patellar tendon advancement or patellar tendon shortening. The purpose of this study was to establish a consensus through expert orthopedic opinion, using a modified Delphi process to describe the surgical indications for distal femoral extension osteotomy and patellar tendon advancement/patellar tendon shortening. A literature review was also conducted to summarize the recent literature on distal femoral extension osteotomy and patellar tendon shortening/patellar tendon advancement.Method:A group of 16 pediatric orthopedic surgeons, with more than 10 years of experience in the surgical management of children with cerebral palsy, was established. The group used a 5-level Likert-type scale to record agreement or disagreement with statements regarding distal femoral extension osteotomy and patellar tendon advancement/patellar tendon shortening. Consensus for the surgical indications for distal femoral extension osteotomy and patellar tendon advancement/patellar tendon shortening was achieved through a modified Delphi process. The literature review, summarized studies of clinical outcomes of distal femoral extension osteotomy/patellar tendon shortening/patellar tendon advancement, published between 2008 and 2022.Results:There was a high level of agreement with consensus for 31 out of 44 (70%) statements on distal femoral extension osteotomy. Agreement was lower for patellar tendon advancement/patellar tendon shortening with consensus reached for 8 of 21 (38%) of statements. The literature review included 25 studies which revealed variation in operative technique for distal femoral extension osteotomy, patellar tendon advancement, and patellar tendon shortening. Distal femoral extension osteotomy and patellar tendon advancement/patellar tendon shortening were generally effective in correcting knee flexion deformities and extensor lag, but there was marked variation in outcomes and complication rates.Conclusion:The results from this study will provide guidelines for surgeons who care for children with cerebral palsy and point to unresolved questions for further research.Level of evidence:level V.     

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.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 8 (October), 2001: pp 808–817     

Arthroscopic anterior cruciate ligament reconstruction using the double press-fit technique: An alternative to interference screw fixation

Purpose: Patellar tendon autograft fixation in arthroscopic anterior cruciate ligament reconstruction is commonly accomplished using interference screws. However, improper insertion of the screws may reduce primary stability, injure the posterior femoral cortex, or displace hardware into the joint. Even if placed properly, metallic screws interfere with postoperative magnetic resonance imaging. In case of revision surgery, removing screws may be difficult and leaves bone defects. Type of Study: Retrospective study. Methods: An arthroscopic technique was developed that achieves patellar tendon autograft fixation by press-fit without any supplemental internal fixation. Forty patients were examined clinically and by KT-1000 arthrometer 28.7 months (range, 22 to 40 months) postoperatively. Results: The mean difference in side-to-side laxity was 1.3 mm (SD 2.2) and the results according to the IKDC score were as follows: 7 A, 28 B, 5 C, and 0 D. Conclusions: The double press-fit technique we present avoids all complications related to the use of interference screws and creates an ideal environment for osseous integration of the bone–patellar tendon–bone autograft. Concurrently, it achieves a stable fixation of the autograft and allows early functional rehabilitation. However, fixation strength depends on bone quality and the arthroscopic procedure is demanding.     

Biomechanical comparison of hamstring and patellar tendon graft anterior cruciate ligament reconstruction techniques: The impact of fixation level and fixation method under cyclic loading

Purpose: To mechanically test different reconstruction techniques of the anterior cruciate ligament (ACL) under incremental cyclic loading and to evaluate the impact of the level and method of graft fixation on tensile properties of each technique. Type of Study: In vitro biomechanical study. Methods: Four hamstring and 1 patellar tendon reconstruction techniques were performed on 40 young to middle-aged human cadaveric knees (average age, 39 years). An anterior drawer with increasing loads of 20 N increments was applied at 30° of knee flexion. Anatomic, direct interference screw fixation was tested in 2 hamstring and in the patellar tendon groups. Nonanatomic (extracortical) graft anchorage was tested in the remaining 2 hamstring groups with indirect graft fixations on both sides and the combination of indirect tibial and direct femoral fixation. Structural properties were determined throughout the cyclic loading test. Results: The more anatomic reconstruction techniques provided significantly higher structural properties and smaller loss of fixation compared with nonanatomic, extracortical fixation, with indirect repair on both fixation sites resulting in the lowest structural properties. The tibial fixation site was the weakest link in all of the anatomic reconstructions. Patellar tendon fixation with attached bone blocks in both bone tunnels significantly improved construct stiffness and decreased graft slippage. Conclusions: The results of this study suggest that anatomic fixation should be preferred for anchorage of hamstring tendons and linkage materials should be avoided. Direct soft-tissue fixation with interference screws still allows considerable graft slippage, which can be limited by using a bone block or application of a backup or hybrid fixation, especially on the tibial fixation site.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 3 (March), 2002: pp 304–315     

Arthroscopic double-bundled posterior cruciate ligament reconstruction with quadriceps tendon–patellar bone autograft

Summary: An arthroscopic technique for double-bundled reconstruction for posterior cruciate ligament with quadriceps tendon–patellar bone autograft is presented. Anterolateral and posteromedial tunnels were created to simulate and reproduce the double-bundle structure of the posterior cruciate ligament. The bone plug is situated at the tibial tunnel and fixed by a titanium interference screw. Each of the bundles of tendon graft is rigidly fixed at the femoral tunnel with a bioabsorbable screw.Arthroscopy: The Journal of Arthroscopic and Related surgery, Vol 16, No 7 (October), 2000: pp 780–782     

Shortening of the patellar tendon after anterior cruciate ligament reconstruction

In this prospective study, patellar height changes were investigated after anterior cruciate ligament (ACL) reconstruction with a mean follow-up of 22.4 months. A total of 114 patients were included. Fifty- two patients (group A) were treated by multiple suture repair, 27 patients (group B) underwent acute ACL reconstruction, and 35 patients (group C) underwent ACL reconstruction > or =6 weeks after injury with a patellar tendon graft. The patellar vertical height ratios (VHR) were evaluated preoperatively (VHR 1), 6 months postoperatively (VHR 2), and at follow-up (VHR 3). For the studied questions, the following answers were obtained: (1) The change of the patella height was the same in all three groups (i.e., disregarding the different surgical procedures). (2) The time elapsed between injury and ACL reconstruction did not influence the shortening of the patellar tendon. (3) Women showed a more pronounced shortening of the patellar tendon than did men. (4) A significant shortening of the patellar tendon occurred in 30% of our patients, and the process of shortening was finished 6 months postoperatively. (5) Anterior knee pain was present in 27.2% of our patients and occurred significantly more often after patellar tendon graftings. (6) Age had no influence on the changes of the patellar height.Arthroscopy 1998 Sep;14(6):592-6     

Tibial tunnel enlargement following anterior cruciate ligament reconstruction with patellar tendon autograft

Purpose: The purpose of this study was to prospectively evaluate changes in the tibial bone tunnel following endoscopic anterior cruciate ligament (ACL) reconstruction with patellar tendon autograft. We used computed tomography (CT) sequentially to monitor the time course of these changes over a 2-year period and correlated the results to clinical outcome and instrumented laxity measurements. Type of Study: Case series. Methods: Thirty-four patients (11 women, 23 men; mean age, 26.4 ± 4.5 years) who underwent endoscopic patellar tendon ACL reconstruction, were evaluated clinically according to IKDC, Lysholm, and Tegner scores as well as with respect to changes in tibial tunnel morphology over a 2-year period. Subsequent CT scans were performed at 1 and 6 weeks and at 3, 6, 12, and 24 months postoperatively. The tibial bone tunnel was measured in the sagittal and coronal planes at 5 different levels (L1 to L5). Results: The diameters of the tibial tunnel increased an average overall by 30.6% in the sagittal plane and 16.4% in the coronal plane within 2 years. The enlargement was significantly higher (P <.05) in the mid portion of the tunnel (L 2/3: 44.0% and 47.9% in the sagittal and 29.8% and 29.9% in the coronal plane, respectively), which resulted in a uniform cavity-type appearance. The percentage of change in tunnel size was significantly higher (P <.05) within the first 6 weeks following surgery compared with all other time intervals. No correlation between the amount of tunnel enlargement and the clinical results or between tunnel enlargement and KT-1000 measurements could be detected. Conclusions: Endoscopic ACL reconstruction is associated with tibial tunnel enlargement, which is already present within weeks following surgery. However, no negative effects on the clinical results were found over a 24-month period in our study population.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 2 (February), 2001: pp 138–143     

Patellar versus hamstring tendons in anterior cruciate ligament reconstruction: A meta-analysis

Purpose: To compare the outcome of ACL reconstuction using patellar tendon (PAT) to that when using hamstring tendons. Type of Study: Meta-analysis of controlled trials of patellar tendon versus hamstring tendons for ACL reconstruction. Methods: Meta-analysis is a systematic method for statistical analyses that allows compilation of combined data from various independent studies. This allows one to assess the potential benefits of various treatments when conclusions based on individual studies are difficult to assess. We conducted a meta-analyses (M-A) using controlled trials (CTs) to determine if there are differences between the 2 methods. Although both surgical techniques have potential for good results, we hypothesized that there are differences in outcomes between these techniques. We included CTs that used standard evaluation techniques with a minimum 2-year follow-up. Outcomes evaluated included: return to preinjury level of activity, KT testing, Lachman scores, pivot shift scores, range of motion (ROM) loss in flexion and extension, complications, and failures. Relative risks for each outcome were calculated for each study and pooled across studies using a fixed effects method. Results: Four studies fulfilled our inclusion criteria. Relative risks with 95% confidence intervals and P values were obtained for each of the outcomes listed above. The results show significant differences between PAT and semitendinosus and gracilis tendon (ST&G) reconstructions. PAT patients have a greater chance of attaining a statically stable knee (as measured by KT) and nearly a 20% greater chance of returning to preinjury activity levels. Conclusions: Although both techniques, as performed in the late 1980s and early 1990s, yielded good results, PAT reconstuction led to higher postoperative activity levels and greater static stability than hamstring reconstruction. This is statistically significant based on this meta-analysis.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 3 (March), 2001: pp 248–257     

Complications in Brief: Quadriceps and Patellar Tendon Tears

Effective treatment of knee extensor mechanism disruptions requires prompt diagnosis and thoughtful decision-making with surgical and nonsurgical approaches. When surgery is chosen, excellent surgical technique can result in excellent outcomes. Complications and failures arise from missed or delayed diagnoses and from technical problems in the operating room. In particular, inappropriate surgical timing (especially late surgery), misplaced patellar drill holes, and failure to address concomitant injuries can result in complications seen when repairing a patellar or quadriceps tendon tear. We review the complications that can occur during treatment of these injuries (Table 1).

Pyridinoline in relation to ultimate stress of the patellar tendon during healing: An animal study

The ultimate stress of the central one-third of the patellar tendon was studied in a gap wound-healing model in the rat. The specimens were also analyzed for collagen and nonreducible crosslinks, as measured by hydroxyproline and pyridinoline content, respectively. Thirty days after injury, the ultimate stress of the healing patellar tendon was restored to an average of 71% of the control value and remained constant over time. The pyridinoline content of the healing tendon was twice the control value by 30 days after injury and reached a plateau; however, the hydroxyproline content did not change significantly over time. Stepwise regression analysis demonstrated that pyridinoline was a better biochemical marker for ultimate stress than was hydroxyproline. The current study provides insights into the functional behaviour of the healing patellar tendon by establishing the relationship between the two biochemical components and the ultimate stress of the healing patellar tendon. This study also suggests the possibility of using pyridinoline content as an indirect marker of the ultimate stress because in vivo assessment is impossible.     

Chondral and osteochondral injuries associated with acute patellar dislocation

Purpose: The purpose of this study was to evaluate the frequency and precise pathology of articular cartilage injuries after acute patellar dislocation. Type of Study: Case series. Methods: In 39 consecutive knees with initial lateral patellar dislocation, the articular cartilage injuries were examined using arthroscopy or macroscopic observation. Results: Thirty-seven knees (95%) had articular cartilage injuries of the patellofemoral joint and 2 knees (5%) had no cartilage injury. In all 37 knees (95%), articular cartilage injuries were observed in the patella. The appearances were categorized into 3 groups: cracks alone (9 knees), cartilage defect caused by osteochondral or chondral fracture (7 knees), and cartilage defects caused by osteochondral or chondral fracture associated with cracks (21 knees). The main site of osteochondral fracture was the medial facet, and the main site of cracks was the central dome. Twelve knees (31%) had cartilage injury of the lateral femoral condyle. Conclusions: From this study, articular cartilage injuries, especially of the patella, seem to be common occurrences after acute patellar dislocation. Chondral and osteochondral injuries of the patella were classified into 3 groups.     

Reconstruction of a chronic patellar tendon rupture with semitendinosus autograft

Introduction

Successful outcome following patellar tendon rupture requires robust restoration of the extensor mechanism continuity. Rupture of the patellar tendon occurs most commonly in patients younger than 40 years and is the result of an indirect large force generated by contraction of the quadriceps, which is estimated to be at least 17.5 times of body weight.

Patients and methods

Seventeen patients suffered from chronic rupture of the patellar tendon, underwent reconstruction with hamstring tendon autograft and were enrolled in this prospective study. Average age at time of surgery was 30 years (range, 22–36 years). Average follow-up period was 21 months (range, 12–30 months). Patients underwent regular follow-up after clinical and radiographic preoperative and postoperative evaluation.

Results

Analytical results showed satisfactory function after patellar tendon reconstruction with the use of hamstring tendon autografts.

Conclusion

We suggest that the hamstring tendon autograft is a safe, effective, and acceptable choice for patellar tendon reconstruction, and that it affords good ligament reconstruction.     

Serial magnetic resonance imaging evaluation of the patellar tendon after posterior cruciate ligament reconstruction

Purpose: Our purpose was to prospectively analyze serial changes in magnetic resonance imaging (MRI) signal of the bone–patellar tendon–bone autograft when used for posterior cruciate ligament (PCL) reconstruction and to retrospectively determine at mid-term follow-up the relationship between MRI graft appearance and clinical stability in patients who have undergone arthroscopic PCL reconstruction with a bone–patellar tendon–bone autograft. Type of Study: One prospective serial blinded study and 1 retrospective blinded study. Methods: The first part of the study focused on MRI scans obtained at 3, 6, 9, and 12 months postoperatively in a case series of 10 consecutive patients who underwent arthroscopically assisted PCL reconstruction (group A), and of 10 patients who underwent combined ACL-PCL arthroscopic reconstruction (group B). For the second part of the study, MRI scans were obtained in a retrospective series of 10 patients at mid-term follow-up after PCL arthroscopic reconstruction (group C). Signal intensity of 3 zones, corresponding to the proximal, middle, and distal intra-articular graft zones, was evaluated according to the Howell et al. classification. Fiber continuity assessment was performed using a modified Kühne et al. score. The signal intensity of the 3 zones was independently scored. Knee stability was clinically and instrumentally graded according to the IKDC evaluation form (group 4). A multivariance analysis and grouped t test were used for statistical evaluation. Results: In group A, the average MRI evaluation score was 7.65 ± 1.6 at 3 months, 3.8 ± 0.6 at 6 months, 4.75 ± 1 at 9 months and 6.25 ± 1.2 at 1 year. The portion of graft exiting the femoral tunnel exhibited increased signal and faster maturation than the tibial tunnel. In group B (combined ACL-PCL reconstruction), the graft showed slower graft healing with an average MRI score of 4.85 ± 0.7 at 3 months, 1.9 ± 0.7 at 6 months, 3.9 ± 0.9 at 9 months, and 5.3 ± 1.1 at 1 year. At 1 year follow-up, there was no correlation between MRI appearance and stability in group A, even with MRI findings of fiber continuity. However, at long-term evaluation (group C), a strict correlation between MRI appearance and achieved stability was found. Conclusions: The patellar tendon when used for PCL reconstruction requires more than 1 year to achieve a low-signal intensity over its entire course, and the distal zone near the tibial tunnel shows a slower healing process. MRI graft assessment is useful only 1 year or more following PCL reconstruction.     

The effect of soft-tissue graft fixation in anterior cruciate ligament reconstruction on graft-tunnel motion under anterior tibial loading

Purpose: To compare the motion of an anterior cruciate ligament (ACL) replacement graft within the femoral bone tunnel (graft-tunnel motion) when a soft-tissue graft is secured either by a titanium button and polyester tape (EndoButton fixation; Acufex, Smith & Nephew, Mansfield, MA) or by a biodegradable interference screw (Biointerference fixation; Endo-fix; Acufex, Smith & Nephew) An additional purpose was to evaluate the effect of the graft-tunnel motion on the kinematics of ACL-reconstructed knees and in situ force of the ACL replacement graft. Type of Study: Biomechanical experiment using an in vitro animal model. Methods: ACL reconstruction with a flexor tendon autograft was performed in 8 cadaveric knees of skeletally mature goats. The knee kinematics and the in situ force in the ACL replacement graft in response to anterior tibial loads were evaluated using the robotic/universal force-moment sensor testing system. The longitudinal and transverse graft-tunnel motion during anterior tibial loading was determined based on radiographic measurements parallel and perpendicular to the femoral bone tunnel, respectively. Results: In response to an anterior tibial load of 100 N, the longitudinal graft-tunnel motion for EndoButton fixation and Biointerference fixation was 0.8 ± 0.4 mm and 0.2 ± 0.1 mm, respectively (P < .05), whereas the transverse graft-tunnel motion was 0.5 ± 0.2 mm and 0.1 ± 0.1 mm, respectively (P < .05). Furthermore, the anterior tibial translation for EndoButton fixation (5.3 ± 1.2 mm) was also significantly larger than that for Biointerference fixation (4.2 ± 0.9 mm) (P < .05). With both fixations, however, no significant difference between the in situ forces in the ACL replacement graft and that in the intact ACL could be detected. Conclusions: EndoButton fixation of a soft-tissue graft via an elastic material resulted in significantly larger graft-tunnel motion, and consequently, greater anterior knee laxity compared with more rigid fixation using an interference screw closer to the intra-articular entrance of the bone tunnel. In terms of force distribution, the ACL replacement graft in both fixations still functioned as a primary restraint to an anterior tibial load close to the intact ACL.     

Intra-operative patellar fracture during chronic patellar tendon rupture reconstruction: salvage and prophylactic modified techniques

Management of chronic neglected patellar tendon rupture represents a challenging condition for the orthopedic surgeons to deal with due to many factors such as quadriceps muscle atrophy, superior migration of the patella, e.g., patella alta, peri-patellar adhesions and patellar tendon atrophy. Such difficulties might be further complicated by intra-operative patellar fracture during patellar tendon reconstruction. In the current article, the authors report (1) a salvage procedure for such devastating intra-operative complication, based on bypassing the patella and gaining the advantage of the quadriceps tendon for structural and functional restoration of the knee extensor mechanism, and (2) prophylactically a technical modification of patellar tendon reconstruction guarding against such inadvertent patellar fracture.

     

Acute traumatic rupture of the patellar tendon in pediatric population: Case series and review of the literature

BackgroundIntact knee extensor mechanism is required for the normal function of the lower extremity. Patellar tendon rupture is a relatively rare injury with peak age incidence around 40 years and usually occurs midsubstance. The occurrence of pure patellar tendon rupture without bony avulsion is an extremely rare injury in the pediatric population with few cases reported in the literature with limited information regarding frequency, complications, and outcomes in children. However, due to increased participation in sports and high-energy recreational activities during childhood, the frequency of such injuries has progressively increased.ObjectiveTo evaluate the frequency of pediatric patellar tendon rupture injuries and describe the radiological findings, treatment modalities, and outcome of such injuries.MethodsDemographic and clinical data on a series of patients who sustained patellar tendon rupture were reviewed. These data included age at time of injury, sex, laterality, mechanism of injury, associated injuries, complications, presence or absence of Osgood-Schlatter disease, diagnostic imaging such as plain radiographs and magnetic resonance images (MRI), surgical technique, method of fixation, period of postoperative immobilization, total duration of physiotherapy, time to return to sports activities and follow-up duration. Insall-Salvati ratio was calculated on the preoperative lateral x-ray. The functional outcome was evaluated with regard to final knee active range of motion (AROM), manual quadriceps muscle testing, and presence or the absence of terminal extension lag. Clinical outcome rating using knee society score (KSS) was performed and functional outcome was further classified according to the calculated score.ResultsFive male patients with patellar tendon rupture (7%) were identified among 71 pediatric patients who sustained acute traumatic injury of the knee extensor mechanism. The mean age at the time of injury was 13.6 years (range: 12–15 years). The injury occurred in relation to sports activities in 4 patients. Osteogenesis imperfecta and Osgood-Schlatter disease were identified in 2 patients. High riding patella is the hallmark diagnostic sign detected in plain x-ray with preoperative Insall-Salvati ratio ranged from 1.7 to 2.5. Three patients had pure soft tissue avulsion distally from the proximal tibia, 1 patient had pure soft tissue avulsion proximally from the inferior patellar pole, and 1 patient with midsubstance tendinous disruption. No associated intra-articular lesions were identified. Suture bridge double row technique, transpatellar suturing, and transosseous suturing through the proximal tibia were used for patellar tendon reinsertion. After a mean follow-up period of 18. 4 weeks (range: 10–30 weeks), patients achieved AROM ranging from 0 to 120° to 0–137° without terminal extension lag. The mean time to return to sports activity was 22 weeks (range: 13–30 weeks). Quadriceps muscle strength was 5/5 at the final follow-up visit in all patients; however, relative muscle atrophy was noted in comparison to the other side in one patient. The mean KSS was 91.8 points (range: 79–100 points) with excellent outcome in 4 patients and good outcome in 1 patient.ConclusionPatellar tendon rupture is rare in the pediatric population and represents 7% of pediatric patients who sustained acute traumatic injury of the knee extensor mechanism. Ruptures may occur midsubstance, or from proximal or distal insertions. High riding patella is the hallmark diagnostic sign for such injury. Although rare, it is considered a serious injury that necessitates early diagnosis and surgical intervention. Functional range of motion was obtained in all patients with different modalities of treatment.