Surgical treatment of patellar tendon rupture after total knee arthroplasty with a double-row repair method using the hamstring tendons: A novel technique with functional results

BACKGROUND

Patellar tendon rupture (PTR) is extremely rare but serious complication after primary or revision total knee arthroplasty. Due to the serious failure rates of end-to-end repair techniques, various augmentation techniques have been described. In this study, the results of patients with PTR after reconstruction using our own technique with semitendinosus (ST) and gracilis tendons taken from the affected side were evaluated retrospectively.

METHODS

A total of 14 patients, whose diagnosis was made based on physical examination and clinical findings, and supported radiologically (ultrasonography), were included in the study. In these patients, reconstruction was performed using double-row repair technique with the ST and gracilis tendons. Active-passive knee joint range of motion, active knee extension loss, and the Caton-Deschamps index at preoperative and final follow-up visits were compared. Tegner-Lysholm knee score and Kujala score were used to evaluate functional results.

RESULTS

In 14 patients (8 women and 6 men) with a mean age of 68.1 years, the median time between injury and surgery was 6.6 weeks. In all patients, the rupture was in the distal part of the patellar tendon. While the median preoperative Caton-Deschamps index was 1.8, the postoperative median value was found to be 1.25 after an average follow-up of 3.8 years (P = .014). The median preoperative knee extension loss decreased from 25° to 5° postoperatively. Tegner-Lysholm knee score and Kujala score of the patients at their last follow-up were significantly increased (P < .01).

CONCLUSION

For PTR developing after total knee arthroplasty, the double-row reconstruction technique with ST and gracilis tendons is effective.

Simultaneous Bilateral Patellar Tendon Rupture: A Systematic Review

The extensor mechanism of the knee can be damaged due to various modes of injury, which, in most cases, will require urgent surgical intervention for repair. Single patellar tendon ruptures are uncommon, but simultaneous bilateral events are even rarer and have been scarcely reviewed in English literature. Research in this area is mainly confined to case series, with some literature reviews but no evidence of more substantial analysis. Therefore, this systematic review was done to analyse the existing literature on bilateral simultaneous patellar tendon ruptures and propose a systematic and standardised approach to diagnosing and managing these injuries. A systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The search terms included 'bilateral patellar tendon rupture', 'bilateral', 'patellar', 'tendon' and 'rupture'. Three independent reviewers conducted searches in PubMed, OvidSP for Medline, Embase and the Cochrane Library using the same search strategy. The eligibility criteria included studies on bilateral concomitant patellar tendon rupture published in English. Bilateral simultaneous patellar tendon ruptures of traumatic and atraumatic origin in human patients were included. The study types comprised case reports and literature reviews. The key limitation of this study was the low number of patients covered by the eligible literature. Patellar tendon ruptures are a rare and scarcely documented injury, and there is a need for studies with a high level of evidence, especially regarding surgical treatment choice and methods, as well as post-operative management, which could potentially lead to improved outcomes in the management of this injury.

Outcomes and Complications Following Chronic Patellar Tendon Repair: A Systematic Review

The purpose of this systematic review is to report outcomes and complications following the reconstruction of chronic patellar tendon ruptures. Four databases (Cochrane Database of Systematic Reviews, PubMed, Embase, MEDLINE) were searched from inception to July 2021. Inclusion criteria included articles that (1) analyzed outcomes and complications following chronic patellar tendon reconstruction (>4 weeks from injury to repair), (2) were written in English, (3) greater than five patients, and (4) a minimum 2-year follow-up. Exclusion criteria included (1) non-original research and (2) patellar tendon repair/reconstruction with prior total knee arthroplasty. Data on outcome metrics and complications were extracted from the included studies and reported in a qualitative manner. Nine studies (number of patients = 96) were included after screening. Seven studies analyzed autograft reconstruction, and three of those seven studies analyzed reconstructions with additional augmentation. The remaining two studies evaluated reconstruction utilizing a bone-tendon-bone (BTB) allograft. Four of the autograft studies (n=40 patients) showed a range of post-operative mean Lysholm scores of 74-94. Additionally, four studies reported a post-operative extensor lag of 0-3°. Post-operative protocol for autograft studies included delayed motion and was either contained to a bivalved cast or a hinged knee brace for six weeks. The two allograft studies reported a range of mean Lysholm scores from 62 to 67, and each immobilized the leg in full extension until six weeks. While chronic patellar tendon ruptures are a rare injury of the extensor mechanism, there are viable options for reconstruction. Overall, chronic patellar tendon ruptures reconstructed with both autograft and allograft will provide fair to good outcomes with low complication rates. Following surgery, immobilization for at least six weeks should be emphasized to protect the graft and optimize patient outcomes.

Patellar Tendon Reconstruction Using Peroneus Longus Tendon Autograft Following Revision Knee Arthroplasty: A Case Report

Patellar tendon rupture is a rare but serious complication resulting in loss of knee extension that may develop during and after total knee arthroplasty and negatively affects the patient's quality of life. There are a number of surgical options available, from primary repair to reconstruction. Peroneus longus tendon autograft has begun to be used for knee extensor mechanism repair in recent years. In this case report, we aimed to present the case of a patient with traumatic patellar tendon rupture after revision knee arthroplasty. In conclusion, patellar tendon reconstruction using peroneus longus tendon autograft can be considered a successful method in selected patients following knee arthroplasty. It allows early rehabilitation via stable graft fixation and provides good clinical and functional outcomes in the late period.

Bilateral Patellar Tendon Rupture Following Total Knee Arthroplasty in a Patient With Alkaptonuria: A Case Report

Alkaptonuria (AKU) is a rare hereditary disorder of tyrosine degradation. The disorder is characterized by the accumulation of a pigment called homogentisic acid. Its accumulation can lead to the breakdown of connective tissue, including tendons. This report presents a 46-year-old male with a history of bilateral total knee arthroplasty (TKA) who sustained bilateral patellar tendon rupture after an acute injury. A single-stage bilateral knee revision with direct repair of the extensor mechanism augmented with Achilles allograft was performed. The procedure was successful, and the patient had an excellent post-operative outcome at one year post-operatively. This case attempts to highlight the possible complications from AKU in order to better counsel patients with this condition who are undergoing TKA.

Trends and epidemiology of knee extensor mechanism injuries presenting to United States emergency departments from 2001 to 2020

OBJECTIVES

Injuries to the native extensor mechanism (EM) of the knee are potentially disabling and often require surgical treatment. Large-scale, updated epidemiological data on these injuries is lacking. The objective of the current study was to examine recent trends in EM injuries presenting to United States (US) Emergency Departments (EDs) over the last 20 years using a nationally representative sample.

METHODS

This study retrospectively analyzed the National Electronic Injury Surveillance System (NEISS) database to identify cases of EM injuries (defined as either a quadriceps tendon rupture, a patella fracture, or a patellar tendon rupture) presenting to EDs in the US from 2001 to 2020.

RESULTS

During the study period, an estimated 214,817 EM injuries occurred in an at-risk population of 6,183,899,410 person-years for an overall incidence rate of 3.47 per 100,000 person-years. Patella fractures (PFs) were the most common injury type, representing 77.5% of all EM injuries (overall incidence rate: 2.69), followed by patellar tendon ruptures (PTRs; 13.5%; incidence: 0.48) and quadriceps tendon ruptures (QTRs; 9%; incidence: 0.31). Demographic characteristics and mechanisms of injury differed between injury types. Annual incidence rates increased significantly during the study period for all EM injury types, with PTRs demonstrating the largest relative increase (average annual percent increase: PF, 2.8%; PTR, 7.2%; QTR, 5.3%). Accounting for population growth yielded an increasing incidence of all EM injuries combined from 3.65 in 2001 to 4.9 in 2020. The largest relative increases in incidence rates were observed in older age groups.

CONCLUSION

Extensor mechanism injuries of the knee are increasing in the US, which likely reflects an aging and more active population. These types of injuries are associated with substantial functional impairment and recent increases in incidence rates highlight the need for injury prevention and management strategies.

Extensor mechanism ruptures

Native patellar tendon injuries are seen in younger patients compared to quadriceps tendon ruptures.

Up to a third of the patients may have local (antecedent tendinopathy and cortisone injections) or systemic risk factors (obesity, diabetes, hyperparathyroidism, chronic renal failure, fluoroquinolone or statin use) of injury, these are more frequent in bilateral disruptions.

Complete extensor mechanism disruptions should be repaired surgically. Although isolated primary repair has been reported to have good outcomes in younger patients with acute tears and good tendon quality, augmentation of the repair with autograft, allograft or synthetic material should be considered in patients with poor tendon quality, chronic tears or tendon defects.

High rates of return to work/sports have been reported in native patellar and quadriceps tendon tears, with re-rupture rates <5%.

Extensor mechanism disruptions in patients with a total knee arthroplasty are challenging due to older age, systemic co-morbidities and poor local conditions, resulting in inferior outcomes compared to native extensor mechanism injuries. Some form of augmentation with autograft, allograft or synthetics is advisable in all cases. Salvage procedures such as whole extensor mechanism allografts provide acceptable outcomes in multiply operated knees with extensive bone and soft tissue deficits.

Traumatic Rupture of the Patellar Tendon From the Tibial Tuberosity in an Adult: A Case Report

Patellar tendon ruptures from the tibial tuberosity are very uncommon. Various surgical techniques are described for patellar tendon ruptures from the tibial tuberosity. A 58-year-old male without any predisposing factors had pain and swelling in the right knee due to a road traffic accident. Tense swelling and ecchymosis were present around the right knee with a palpable defect over the patellar tendon and an inability to extend the right knee. An MRI report revealed avulsion of the distal patellar tendon from the tibial tubercle insertion and medial meniscus tear. Primary repair was done with a double-loaded suture anchor and augmentation was done by using a Gracilis tendon. After the months, the knee range of motion (ROM) of the patient reached up to 90 degrees, and there was no extension lag on straight leg raise. Hamstring augmentation with a primary repair is the safest and a good surgical option in elderly patients with patellar tendon ruptures from the tibial tuberosity.

A Strategy for Repair, Augmentation, and Reconstruction of Knee Extensor Mechanism Disruption: A Retrospective Review

Background

The loss of extensor mechanism continuity that occurs with patellar and quadriceps tendon rupture has devastating consequences on patient function.

Purpose

To describe a treatment strategy for extensor mechanism disruption and evaluate the outcomes of 3 techniques: primary repair, repair with semitendinosus tendon autograft augmentation, and reconstruction with Achilles tendon allograft.

Study Design

Case series; Level of evidence, 4.

Methods

The authors reviewed surgeries for extensor mechanism disruption performed by a single surgeon between 1999 and 2019. Patient characteristics, imaging studies, surgical techniques, and outcomes were recorded. Primary ruptures with robust tissue quality were repaired primarily, and first-time ruptures with significant tendinosis or moderate tissue loss were repaired using quadrupled semitendinosus tendon autograft augmentation. Patients with failed previous extensor mechanism repair or reconstruction and poor tissue quality underwent reconstruction with Achilles tendon allograft. The primary outcome was extensor mechanism integrity at a minimum 1-year follow-up, with extensor mechanism lag defined as >5° loss of terminal, active knee extension. Secondary outcomes included postoperative knee range of motion, International Knee Documentation Committee (IKDC) and Tegner activity scores, and the radiographic Caton-Deschamps Index.

Results

Included were 22 patellar tendon and 21 quadriceps tendon surgeries (patients: 82.5% male; mean age, 48.1 years; body mass index, 31). Seventeen (39.5%) cases underwent primary tendon repair, 13 (30.2%) had repair using semitendinosus tendon autograft augmentation, and 13 (30.2%) underwent reconstruction using an Achilles tendon allograft. Seventeen (39.5%) cases had at least 1 prior failed extensor mechanism surgery performed at an outside facility. At the last follow-up, 4 (9.3%) cases had an extensor mechanism lag, no cases required additional extensor mechanism surgery, and all cases were able to achieve >90° of knee flexion. Postoperative IKDC scores were significantly improved with all methods of extensor mechanism surgery, and postoperative Tegner activity scores were significantly improved in patients who underwent primary repair and Achilles tendon allograft reconstruction (P < .05 for all).

Conclusion

Primary repair alone, repair using quadrupled semitendinosus tendon autograft augmentation, and reconstruction using Achilles tendon allograft were all effective methods to restore extensor mechanism and knee function with the proper indications. Persistent knee extensor lag was more common in chronic extensor mechanism injuries after failed surgery, although patients still reported significantly improved postoperative functional outcomes.

Incidence and Risk Factors of Acute Patellar Tendon Rupture, Repair Failure, and Return to Activity in the Active-Duty Military Population

BACKGROUND

Patellar tendon ruptures have a reported incidence of 0.68 per 100,000 person-years in the general population. The epidemiology of surgically treated patellar tendon ruptures in the US military has yet to be reported, which would provide opportunity for identification of risk factors for these otherwise healthy and active patients.

PURPOSE

To determine the incidence of patellar tendon rupture in the Military Health System (MHS) population and to analyze demographic patterns, surgical fixation methods, and rerupture rates.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

We utilized the MHS Data Repository (MDR) to identity active-duty military servicemembers surgically treated for patellar tendon rupture between 2010 and 2015. Records were reviewed for demographic information, injury characteristics, fixation technique, and occurrence of rerupture. Risk factors for rupture were calculated using Poisson regression based on population counts and demographic data obtained in the MDR. Risk factors for rerupture and return to duty were analyzed via univariate analysis and multivariate regression.

RESULTS

A total of 504 operatively treated primary patellar tendon repairs in 483 patients were identified, with an overall incidence of 6 per 100,000 person-years. Mean age was 33.6 years (range, 17-54 years) and 98% of patients were male. Fixation method was 81% bone tunnels and 7% suture anchors, and 12% were unknown. Black race had a higher relative rate ratio for rupture compared with the race categories White (9.21; P < .0001) and Other (3.27; P < .0001). The rupture rate was higher in 35- to 44-year-old patients compared with those aged 18 to 24 years (P < .0001), 25 to 34 years (P < .0001), and 45 to 64 years (P = .004). Return to full previous level of activity occurred in 75.8% of patients, 14.6% returned to activity with limitations, and 9.5% were medically separated. The rerupture rate was 3%. Fixation method, tobacco usage, body mass index, and race were not significant risk factors for rerupture.

CONCLUSION

The incidence of patellar tendon rupture in the US military population is substantially higher than has been reported in the civilian population. Among military personnel, men, Black servicemembers, and those aged 35 to 44 years were at highest risk for patellar tendon rupture. Three-quarters of patients were able to return to full activity without limitations. The rerupture rate was low and unaffected by fixation method.

Extensor Mechanism Reconstruction Using Marlex Mesh: Is Postoperative Casting Mandatory?

BACKGROUND

Extensor mechanism (EM) disruption after total knee arthroplasty is a catastrophic complication. Reconstruction using monofilament polypropylene mesh (Marlex Mesh; CR Bard, Franklin Lakes, NJ) has emerged as the preferred treatment, but reports are limited to the designing institution. This study describes a nondesigner experience and compares 2 postoperative immobilization strategies: long leg cast vs knee immobilizer.

METHODS

A retrospective review of consecutive EM reconstructions between 2012 and 2019 was performed. Primary repairs and allograft reconstructions were excluded, leaving 33 knees (30 patients) who underwent Marlex reconstruction. Mean time from disruption to reconstruction was 14 months, and 14 of 33 (42%) had previous repair or reconstruction attempts. The mean age was 69 years, and mean body mass index was 35 kg/m². Postoperatively, extension was maintained using a knee immobilizer in 19 of 33 (58%) patients, whereas 14 of 33 (42%) patients were long leg casted. Kaplan-Meier analysis determined all-cause survivorship free of mesh failure.

RESULTS

At mean 25-month follow-up, 19 of 33 (58%) EM reconstructions were functioning. Excluding explanted infections (5 recurrent and 2 new), 19 of 26 (73%) EM reconstructions were in situ. Six-year survivorship was 69% and not influenced by immobilization type (cast: 67%, immobilizer: 71%; P = .74). Extensor lag was not associated with immobilization type, improving from a mean preoperative lag of 43° to a mean postoperative lag of 9°. Among successes, University of California at Los Angeles activity and Knee Injury and Osteoarthritis Outcome Score - Joint Replacement score improvements exceeded minimal clinically important difference (2.2-3.3 and 52.5-64.0, respectively).

CONCLUSION

Marlex mesh EM reconstruction is a durable and reliable treatment with acceptable clinical results achievable outside the designer institution. Provided sufficient duration and compliance with postoperative immobilization, similar outcomes can be obtained with either a cast immobilizer or a knee immobilizer.

Enhanced Biomechanical Performance of a Modern Polyester Surgical Mesh for Extensor Mechanism Reconstruction in Total Knee Arthroplasty

BACKGROUND

Extensor mechanism (EM) disruption following total knee arthroplasty is a devastating postoperative complication. Reconstruction with a synthetic mesh is one treatment option, although the optimal mesh material remains unknown. This study sought to compare the mechanical properties of 2 mesh material types that can be used for EM reconstruction.

METHODS

Mechanical properties of a polypropylene mesh (Marlex mesh) and Ligament Advanced Reinforcement System (LARS) mesh were compared using force-displacement data from a material testing machine simulating knee movement during normal human gait. Tension to failure/ultimate tensile load, stiffness coefficients, axial strain, and cyclic hysteresis testing were measured and calculated.

RESULTS

Compared to polypropylene mesh, LARS mesh demonstrated a significantly higher mean ultimate tensile load (2223 N vs 1245 N, P = .002) and stiffness coefficient (255 N/mm vs 14 N/mm, P = .035) in tension to failure testing, and significantly more energy dissipation (hysteresis) in hysteresis testing (771 kJ vs 23 kJ; P ≤ .040). LARS mesh also demonstrated significantly less maximum displacement compared to the polypropylene mesh (9.2 mm vs 90.4 mm; P ≤ .001).

CONCLUSION

Compared to polypropylene mesh, LARS mesh showed superior performance related to force-displacement testing. The enhanced mechanical performance of LARS mesh may correlate clinically to fewer failures, increased longevity, and higher resistance to plastic deformation (extensor lag). Future research should evaluate survivorship and clinical outcomes of these meshes when used for EM reconstruction.

Simultaneous Bilateral Patellar Tendon Rupture in a Young Adult Male: A Case Report and Review of the Literature

A bilateral patellar tendon rupture is extremely rare and has only been documented in case reports. Although the etiology remains unknown, predisposing factors include steroid usage, systemic diseases, and tendinopathies. In the present case, a healthy 33-year-old male with a prior history of bilateral patellar tendonitis and a diagnosis of Osgood-Schlatter disease during adolescence experienced simultaneous bilateral patellar tendon rupture after playing volleyball. He underwent bilateral patellar repair without complications. In the absence of trauma, spontaneous bilateral patellar tendon ruptures are associated with several predisposing factors, including systemic diseases, prior corticosteroid or fluoroquinolone usage, and history of tendinopathy. Injuries can be classified based on the location of the rupture. Bilateral patellar tendon ruptures can be misdiagnosed due to the rarity of cases and the lack of a normal comparative knee. Radiographic techniques can aid in the diagnosis, leading to early surgical treatment and improved outcomes. Early diagnosis and prompt surgical repair contribute to good functional outcomes in this potentially debilitating injury pattern.

Operative Treatment of Acute Patellar Tendon Ruptures

BACKGROUND

The gold standard for patellar tendon repair is a transosseous technique. Suture anchor repair has gained popularity, with recent biomechanical studies demonstrating significantly less gap formation during cyclic loading and significantly higher ultimate failure loads as compared with transosseous repair. These findings have not been substantiated in a large clinical cohort.

PURPOSE

To report demographic and epidemiologic data, clinical and surgical findings, and outcomes and complications of anchor and transosseous suture repairs of acute patellar tendon ruptures.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

All patients who underwent a primary repair of a traumatic patellar tendon rupture within 45 days of injury between 2006 and 2016 were retrospectively reviewed. Surgery was performed at a multisurgeon (120 surgeons) multicenter (14 centers) community-based integrated health care system. Patient demographic information, repair type, complications, and time from surgery to release from medical care were recorded.

RESULTS

A total of 361 patients (374 knees) met our inclusion criteria. The mean age was 39.8 years (range, 9-86 years), and 91.7% were male. There were 321 transosseous and 53 anchor repairs. There was no significant difference in the mean age (P = .27), sex (P = .79), tourniquet time (P = .93), or body mass index (P = .78) between the groups. There was a significant difference in rerupture rate between transosseous and anchor repairs (7.5% vs 0%, respectively; P = .034). Based on logistic regression, transosseous repair had 3.24 times the odds of reoperation verseus anchor repair (95% CI, 0.757-13.895; P = .1129). The infection rate was 1.6% for transosseous repair and 7.5% for anchor repair (P = .160). There was no difference in time to release from medical care: 18.4 weeks for anchor and 17.1 weeks for transosseous repairs (P = .92).

CONCLUSION

Anchor repair demonstrated a significant decrease in rerupture rate when compared with transosseous repair. There was no difference in reoperation rate, infection rate, or time to release from medical care.

Management Options for Extensor Mechanism Discontinuity in Patients With Total Knee Arthroplasty

Extensor mechanism disruption is one of the most dreaded complications of total knee arthroplasty. At times, the disruption is associated with infection, the paucity of soft tissue, and loosening of implants. Treatment decisions made by surgeons are guided by their experience and expertise. The purpose of this article is to provide the readers with an evidence-based comprehensive review which, in turn, should help them in diagnosis and selecting the best treatment strategy for individual patients. In the following article, we have discussed extensor mechanism disruptions of varying severity at various anatomical levels. We also covered both operative and non-operative measures in different clinical situations. The analysis of various articles published in the literature would also help orthopedic surgeons to understand the probable outcomes of the particular treatment option chosen and to counsel their patients accordingly.

Treatment of Extensor Tendon Disruption After Total Knee Arthroplasty: A Systematic Review

BACKGROUND

Patellar or quadriceps tendon ruptures after total knee arthroplasty constitute a devastating complication with historically poor outcomes. With advances in soft tissue reconstruction and repair techniques, treatment has become more nuanced. Numerous graft options for reconstruction and suture techniques for repair have been described but there is no consensus regarding optimal treatment.

METHODS

A search of PubMed, MEDLINE, Embase, and Scopus was conducted. Articles meeting inclusion criteria were reviewed. Type of intervention performed, type of injury studied, outcome measures, and complications were recorded. Quantitative and qualitative analyses were performed.

RESULTS

Twenty-eight articles met inclusion criteria. The complication rate after repair of patellar tendon (63.16%) was higher than the complication rate after repair of quadriceps tendon (25.37%). However, the complication rate for patellar and quadriceps tendon tears after autograft, allograft, or mesh reconstruction was similar (18.8% vs 19.2%, respectively). The most common complication after extensor mechanism repair or reconstruction was extension lag of 30° or greater (45.33%). This was followed by re-rupture and infection (25.33% and 22.67%, respectively). Early ruptures had a higher overall complication rate than late injuries.

CONCLUSION

Extensor mechanism disruption after total knee arthroplasty is a complication with high morbidity. Reconstruction of patellar tendon rupture has a much lower complication rate than repair. Our findings support the recommendation of patellar tendon reconstruction in both the early and late presentation stages. Quadriceps rupture can be treated with repair in early ruptures or with reconstruction in the late rupture or in the case of revision surgery.

Survivorship of Extensor Mechanism Allograft Reconstruction After Total Knee Arthroplasty

BACKGROUND

Extensor mechanism disruption remains a devastating complication after total knee arthroplasty. The purpose of this study is to describe the outcomes of extensor mechanism allograft (EMA) reconstruction in a large single-center case series.

METHODS

Consecutive patients with a previous total knee arthroplasty undergoing extensor mechanism reconstruction using a fresh-frozen EMA tensioned in full extension were identified retrospectively from single-center institutional database (N = 25 patients, 26 knees; mean follow-up 68 months [range 22-113 months]). The primary outcome was initial allograft failure, defined as removal of the allograft or extensor lag >30 degrees at most recent follow-up.

RESULTS

Sixty-nine percent (18/26) of knees had retained their initial allograft reconstruction at their latest follow-up despite reoperation rates of 58% (15/26). A younger age was significantly associated with failure of the initial allograft reconstruction. Knee Society Scores increased from 101 (38 standard deviation [SD]) to 116 (40 SD) at most recent follow-up for the group as a whole (P = .4). Patients undergoing a reoperation for any cause had lower Knee Society Scores (101 [SD 38] vs 138 [SD 32], respectively; P = .04) at most recent follow-up.

CONCLUSION

EMA reconstruction shows adequate overall intermediate-term survival; however, reoperation rates were high and associated with worse functional outcomes.

Focal intratendinous radiolucency: A new radiographic method for diagnosing patellar tendon ruptures

BACKGROUND

Diagnosis of patellar tendon rupture is usually based on clinical history and examination. In equivocal cases, imaging may be required. Lateral radiograph is a simple and cost-effective method for prompt diagnosis. However, no specific radiological sign has been described. Rather than utilising patella alta as an indirect measure of patellar tendon rupture, we hypothesise that a focal intratendinous radiolucency is another reliable and accurate radiological sign for diagnosis. Sensitivity and specificity analysis was undertaken to evaluate the diagnostic value of this radiographic sign.

METHODS

Lateral radiographs of mid-substance patellar tendon ruptures from 19 patients were analysed. These were then randomised with another 19 normal knee radiographs from age-matched patients to create a pool of 38 radiographs for interpretation. Six independent interpreters who were blinded to the diagnosis were requested to indicate whether rupture was present or absent based on the visualisation of a focal intratendinous radiolucency in the patellar tendon. The Insall-Salvati (IS), Caton-Deschamps (CD) and Blackburne-Peel (BP) ratios were measured in the same radiographs. Sensitivity and specificity for each of the radiographic measurements were calculated. Inter- and intraobserver correlations were reported in kappa statistics.

RESULTS

The average sensitivity and specificity for focal radiolucency in the patellar tendon substance were 82.5% and 95.2%, respectively. Sensitivity and specificity for the IS ratio were 84.2% and 78.9%, for CD was 68.4% and 84.2% and for BP was 68.4% and 89.4% respectively.

CONCLUSION

The presence of a focal intratendinous radiolucency in the patellar tendon is both accurate and reliable in diagnosing patellar tendon ruptures.