Quadriceps tendon malalignment is an independent anatomical deformity which is the primary abnormality associated with lateral facet patellofemoral joint osteoarthritis

PURPOSE

The purposes of this study are to, firstly, develop techniques to accurately identify extensor mechanism malalignment by measuring the alignment of the quadriceps tendon (QTA) with computerized tomography (CT) scans. Secondly, to investigate correlations between QTA and lower limb bony anatomical variations within a representative normal population. Lastly, to evaluate the clinical significance of QTA by establishing its potential connection with lateral facet patellofemoral joint osteoarthritis (LFPFJOA).

METHOD

CT scans were orientated to a mechanical axis reference frame and three techniques developed to measure the alignment of the quadriceps tendon. Multiple measurement of bony alignment from the hip to the ankle were performed on each scan. A series of 110 cadaveric CT scans were measured to determine normal values, reproducibility, and correlations with bony anatomy. Secondly, a comparison between 2 groups of 25 patients, 1 group with LFPFJOA and 1 group with isolated medial OA and no LFPFJOA.

RESULTS

From the cadaveric study, it was determined that the alignment of the quadriceps tendon is on average 4.3° (SD 3.9) varus and the apex of the tendon is 9.1 mm (SD 7.7 mm) lateral to the trochlear groove and externally rotated 1.9° (SD 12.4°) from the centre of the femoral shaft. There was no association between the quadriceps tendon alignment and any other bony measurements including tibial tubercle trochlear groove distance (TTTG), coronal alignment, trochlear groove alignment and femoral neck anteversion. A lateralized QTA was significantly associated with LFPFJOA. QTA in the LFPFJOA group was 9.6° varus (SD 2.8°), 21.3 mm (SD 6.6) lateralised and 17.3° ER (SD 11°) compared to 5.5° (SD 2.3°), 10.7 mm (SD 4.9) and 3.3° (SD 7.2°), respectively, in the control group (p < 0.001). A significant association with LFPFJOA was also found for TTTG (17.2 mm (SD 5.7) vs 12.1 mm (SD 4.3), p < 0.01). Logistic regression analysis confirmed the QTA as having the stronger association with LFPFJOA than TTTG (AUC 0.87 to 0.92 for QTA vs 0.79 for TTTG).

CONCLUSION

These studies have confirmed the ability to accurately determine QTA on CT scans. The normal values indicate that the QTA is highly variable and unrelated to bony anatomy. The comparative study has determined that QTA is clinically relevant and a lateralised QTA is the dominant predictor of severe LFPFJOA. This deformity should be considered when assessing patella maltracking associated with patella osteoarthritis, patella instability and arthroplasty.

LEVEL OF EVIDENCE

III (retrospective cohort study).

High rate of failure after revision extensor mechanism allograft reconstruction

BACKGROUND

Patients who fail initial extensor mechanism allograft (EMA) reconstruction for extensor mechanism disruption after total knee arthroplasty (TKA) are left with few options. This study evaluated outcomes in patients that underwent revision EMA reconstruction following a failed EMA.

METHOD

Ten patients that underwent revision EMA for failed index EMA with minimum 1-year follow-up were retrospectively reviewed. Patients receiving fresh-frozen EMA (quadriceps tendon, patella, patellar tendon, and tibial tubercle) at index and revision EMA were included. The primary outcome was EMA failure defined as revision surgery, extensor lag > 30°, or Knee Society Score (KSS) < 60 at last follow-up. Descriptive statistics were performed, with p < 0.05.

RESULTS

Mean extensor lag improved from 55.6°±26.7° pre-revision to 32.8°±29.6° (p = 0.13) at mean follow-up of 43.8 months (range, 12-124 months). Mean KSS improved from 41.0 ± 9.5 pre-revision to 73.4 ± 14.5 at last follow-up (p < 0.001). All patients required assistive devices for ambulation at final follow-up: one (10.0%) required a wheelchair, five (50.0%) required a walker, and four (40.0%) required a cane. Seven (70.0%) patients experienced EMA failure at a mean of 33.6 months (range, 2-124) following revision EMA: three (30.0%) were revised for periprosthetic joint infection (one of which also had extensor lag > 30°), three (30.0%) additional patients had extensor lag > 30°, and one (10.0%) patient had KSS < 60 (this patient developed PJI and was treated nonoperatively with chronic antibiotic suppression).

CONCLUSIONS

Revision EMA reconstruction fails at a high rate despite leading to improvements in KSS. Further research is needed to develop effective prevention and treatment strategies for failure after initial EMA reconstruction.

Complications and re-operations after extensor mechanism repair surgery in a large cross-sectional cohort: females and tobacco-users at highest risk for adverse outcomes

PURPOSE

There is little information on patients most at risk for poor outcomes following surgical repair of extensor mechanism tendon injuries. The purpose of this study is to provide an epidemiological overview of patients undergoing patellar or quadriceps tendon repair and to assess the incidence of postoperative complications, readmissions, and revision repairs among this population.

METHODS

Retrospective data were obtained using the PearlDiver database for patellar tendon repair and quadriceps tendon repair patients between 2010 and 2020. Baseline demographics, incidences of 90-day readmissions and postoperative complications, and reoperation rates were collected for each group. Multivariate logistic regression was performed to assess the predictive power of each demographic variable on the incidence of postoperative complications and reoperations.

RESULTS

In total, 1543 patients underwent patellar tendon repair and 601 underwent quadriceps tendon repair. Complications within 90-days were observed in 33.7% of patients with patellar tendon repair and 39.2% of patients with quadriceps tendon repair. Reoperation rates were 4.2% and 4.8% for patellar tendon repair and quadriceps tendon repair, respectively. Females in both patellar tendon repair and quadriceps tendon repair groups were at significantly higher risk for post-operative complications (patellar tendon repair OR 3.0, 95% CI 2.4-3.7; quadriceps tendon repair OR 2.9, 95% CI 1.9-4.6; p < 0.001 for both). Older age (p < 0.001), female gender (p < 0.001), CCI (p < 0.001), tobacco use (p < 0.001), and obesity (p < 0.01) were all predictors of experiencing at least one complication following patellar tendon repair. For quadriceps tendon repair, female gender (p < 0.001) and CCI (p < 0.001) were the strongest predictors of experiencing at least one complication, while older age, tobacco use, and obesity (p < 0.05 for all) were also significant independent predictors.

CONCLUSION

Patellar tendon repair patients are younger on average than quadriceps tendon repair patients. Although females are less likely to sustain extensor mechanism ruptures compared to males, females are significantly more likely to have at least one complication after quadriceps or patellar tendon repair. These findings may be used by surgeons, patients, and payors to understand who is most at risk for adverse outcomes following extensor mechanism repair surgery, resulting in earlier intervention and counseling to reduce the likelihood of a poor outcome following extensor mechanism repair surgery.

LEVEL OF EVIDENCE

Level III.

Harvesting a second graft from the extensor mechanism for revision ACL reconstruction does not delay return of quadriceps function

PURPOSE

The purpose of this study was to evaluate whether harvesting a second graft from the ipsilateral extensor mechanism adversely affects clinical outcomes in revision anterior cruciate ligament (ACL) reconstruction.

METHODS

A retrospective review of 34 patients undergoing revision anterior cruciate ligament (ACL) reconstruction with either quadriceps tendon (QT) autograft or bone-tendon-bone (BTB) autograft was conducted. Patients with two grafts (BTB+QT) from the extensor mechanism were matched based on age, laterality, and sex to patients who had primary reconstruction with hamstring (HS) autograft followed by revision with either BTB or QT autograft (HS+QT/BTB). Return of quadriceps function was assessed with time to return to jogging in a standardized rehab protocol or time to regain 80% quadriceps strength. Secondary outcomes included International Knee Documentation Committee (IKDC) and Marx scores at 12-month follow-up and return to sport.

RESULTS

There were no significant differences in return to jogging or 80% quadriceps strength (HS 149.5 ± 38.2 days, BTB+QT 131.7 ± 40.1 days, n.s.), number able to return to sport (HS 62%, BTB+QT 93%, n.s.), months to return to sport (HS 10.6 ± 1.4, BTB+QT 10.5 ± 2.3, n.s.), return to pre-injury level of competition (HS 62%, BTB+QT 73%, n.s.), or IKDC (HS 77.2 ± 16.4, BTB+QT 74.8 ± 23.9, n.s.) and Marx scores (HS 9.2 ± 5.3, BTB+QT 8.0 ± 3.7, n.s.) at one-year follow-up.

CONCLUSION

The main finding of the present study was that outcomes for patients who underwent revision ACL reconstruction with a second extensor mechanism autograft were comparable to those seen for patients who underwent revision ACL reconstruction with extensor mechanism autograft after primary ACL reconstruction with hamstring autograft. By better understanding the consequences of harvesting a second graft from the extensor mechanism, surgeons can better decide what graft to use in revision ACL reconstruction.

LEVEL OF EVIDENCE

Level III.

Single-stage procedures for treatment of traumatic patellar osteomyelitis: A retrospective study of 21 patients

INTRODUCTION

We herein report on a series of 21 patients with traumatic patellar osteomyelitis treated by single-stage surgery, and discuss the specific application of single-stage procedures for traumatic patellar osteomyelitis.

METHODS

We retrospectively reviewed the medical records of 21 patients with traumatic patellar osteomyelitis treated in our hospital from January 2010 to April 2018. In a single-stage surgery, aggressive debridement was performed together with application of a tissue flap, especially a gastrocnemius flap (for repair of skin/soft tissue defects and treatment of extensor mechanism defects), and internal refixation of the patellar fracture. The knee joint was exercised early after surgery. Long-term follow-up was performed to evaluate the recurrence of osteomyelitis according to clinical and laboratory signs of infection and to measure the active knee range of motion (ROM).

RESULTS

Single-stage wound treatment was successful in 20 of 21 patients. Treatments included radical debridement together with tissue flap for repair of soft tissue and extensor mechanism defects, and internal refixation of patellar fractures. 14 patients were treated with gastrocnemius flaps. One patient developed recurrent wound infection, which healed after reoperation. At a mean follow-up of 8 ± 2.63 years (range, 3.2-11.4 years), none had developed recurrence. Six patients had nearly full knee ROM (0°-105° to 0°-146°), whereas 11 patients had impaired knee mobility (ROM, 0°-90° to 0°-65°), 3 patients had knee joint stiffness with a ROM of 0°, and 1 patient had knee flexion contracture with a ROM of 78°-130° CONCLUSIONS: Single-stage surgical treatment consisting of various surgical techniques was an acceptable treatment for traumatic patellar osteomyelitis, allowing early exercise of the knee joint. The osteomyelitis did not recur, and most patients' knee ROM was restored to a certain extent, excluding patients with severe damage to the patellar articular surface and inactive functional exercise.

A novel technique with Dacron vascular graft augmentation for knee extensor mechanism repairs: Technical note

Ruptures of the extensor apparatus can have different etiologies and be complicated by underlying situations. Direct repair is not always possible, and reconstruction procedures can be insufficient, which leads to the appearance of multiple augmentation techniques to improve the strength of these constructs. Despite the proven results of these techniques, numerous procedures are described without any gold standard. We present our augmentation method for repairing the knee extensor apparatus with a vascular prosthesis that facilitates healing, does not interfere with the primary procedure, has no donor morbidity or rejection risk, and allows earlier mobilization and rehabilitation. The technique was used in different cases with multiple etiologies that needed reinforcement, with promising results.

Management of Extensor Mechanism Disruption After Total Knee Arthroplasty

Extensor mechanism disruptions following total knee arthroplasty are devastating injuries with complication rates following surgical intervention ranging from 25% to 45%. Primary repair with and without augmentation is appropriate in certain limited clinical settings. Allograft reconstruction has been a popular option; however, synthetic grafts are showing promise and good results. In this article the authors discuss an algorithm for treating these difficult injuries as well as detail the surgical techniques for each approach.

Total Elbow Arthroplasty in the Context of an Olecranon Nonunion: A Surgical Technique and Report of Three Cases

The deficiency of the triceps tendon has been considered a relative contraindication to performing a total elbow arthroplasty. One of the conditions that may compromise triceps integrity is the presence of an olecranon non-union (ON). In this scenario, the placement of a total elbow arthroplasty in a patient with end-stage elbow arthritis is a complex problem to be solved. The aim of this study is to describe the surgical technique for the placement of a TEA in the context of a previous ON and to report the results of three cases. Surgical technique: the focus of the nonunion is identified, and the olecranon fragment is proximally reflected with the triceps tendon to allow accurate exposure of the medullary canal of the ulna and easy access to the joint. With the elbow in a fully flexed position, the previously assembled test prosthesis is placed and the proximal ulna fragment should then be reduced to match the distal ulna. Osteosynthesis with a tension band technique was performed at 45° of elbow extension. A non-absorbable Krackow suture (Ti-Cron 2-0) from the triceps's tendon to the hole of the wire in the distal ulna is applied to decrease the triceps tension traction. Bone grafting is performed when a persistent gap is present at the fracture site following reduction. This technique enables us to achieve a stable elbow with little pain and maintains the extensor apparatus's continuity.

Techniques for extensor mechanism reconstruction after total knee arthroplasty: Is there a clear winner?

Extensor mechanism (EM) disruption after total knee arthroplasty (TKA) is rare, but can result in devastating outcomes for patients including inability to ambulate. Disruption can occur at the quadriceps tendon, patella, or patellar tendon. This complication can be traumatic, but is often atraumatic from an iatrogenic or degenerative etiology. Primary repair for treatment of EM disruption has led to poor results with high failure rates and has mostly been abandoned. Most commonly accepted techniques center around Achilles tendon allograft reconstruction, synthetic mesh reconstruction, or other smaller options. However, to date, there is still no consensus for the optimal EM reconstructive technique due to the heterogeneity and small sample sizes of published studies. The need to identify a consistent and effective surgical technique is paramount to restore quality of life to patients who suffer from EM disruption after TKA. The purpose of this review is to describe the osteology, vasculature, and EM of the knee, identify risk factors associated with EM disruption after TKA, outline the considerations for surgical management, as well as compare and analyze the latest contributions to the literature, in particular allograft versus synthetic mesh, in the reconstruction of the EM after TKA.

The active knee extension after extensor mechanism reconstruction using allograft is not influenced by "early mobilization": a systematic review and meta-analysis

BACKGROUND

Postoperative rehabilitation after extensor mechanism reconstruction (EMR) with allograft following total knee arthroplasty (TKA) is not standardized. This meta-analysis aimed to evaluate the effectiveness of early and late knee mobilization after EMR. The range of motion (ROM) and extensor lag in both groups were also assessed as the secondary endpoint.

METHODS

Following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines, a systematic review of the literature was performed, including studies dealing with the use of allograft for EMR following TKA. Failure was defined as the persistence of extensor lag > 20°. Coleman Methodology Score and Methodological Index for Non-Randomized Studies (MINORS) score were used to assess the quality of studies included. The failure rate was set as the primary outcome in early (4 weeks) and late (8 weeks) mobilization groups after EMR with allograft. Secondary outcomes were postoperative extensor lag and ROM.

RESULTS

Twelve articles (129 knees) were finally selected for this meta-analysis. Late and early knee mobilization was described in five and seven studies, respectively. No difference was noted between both groups' failure rates (11/84 vs. 4/38, respectively; p = 0.69). The mean extensor lag at last follow-up was 9.1° ± 8.6 in the early mobilization group, and 6.5° ± 6.1 in the late mobilization group is not significantly different (p > 0.05). The mean postoperative knee flexion was 107.6° ± 6.5 and 104.8° ± 7 in the early and late mobilization group, respectively.

CONCLUSION

While immobilization after EMR in TKA is mandatory to allow tissue healing, early knee mobilization after four weeks can be recommended with no additional risk of failure and increased extensor lag compared to a late mobilization protocol.

LEVEL OF EVIDENCE

IV, therapeutic study. Registration PROSPERO (International Prospective Register of Systematic Reviews): CRD42019141574.

Combined quadriceps tendon reconstruction and total knee replacement with computer navigation: a case report

Background

Chronic quadriceps tendon rupture is technically challenging for surgeons due to scarring and tendon retraction. The presence of concurrent ipsilateral knee osteoarthritis compounds the issue even further. Although a combined presentation is rare, treatment options to manage each coexisting pathology simultaneously are scarcely reported. We describe the case of a 67-year-old Caucasian male who had such a presentation, and was subsequently treated with a one-stage extensor mechanism autograft reconstruction and total knee replacement with computer navigation.

Case

The patient was a 67-year-old male Caucasian, who had previously sustained an acute rupture of his right quadriceps tendon that was adequately repaired 6 months prior. Despite an initial satisfactory result, he reported deterioration in his mobility in the few months thereafter, with worsening knee pain. His comorbidities consisted of hypertension, asthma, and a body mass index of 40.4 kg/m². Otherwise, there were no risk factors for tendon rerupture. Clinical examination later revealed a large palpable gap in the right suprapatellar region and weakness of active knee extension. No traumatic cause for this new presentation was identified. Suspicion of a chronic quadriceps tendon rupture was confirmed on radiological imaging, but the investigations also noted the presence of severe tricompartmental osteoarthritis of the ipsilateral, native knee joint. The combined procedure took place in one surgical sitting. The total knee replacement with patella resurfacing was performed first and assisted by computer navigation. The quadriceps tendon reconstruction was then conducted sequentially using the patient’s hamstring tendons (semitendinosus and gracilis). The tensile strength was reinforced with use of a Ligament Augmentation and Reconstruction System (LARS) ligament. Initial outcomes were excellent, and these results were maintained at 6 months postoperatively, with the patient reporting no pain and having full range of movement.

Conclusion

Our techniques used have not previously been reported, but are successful options in treating coexisting chronic quadriceps tendon rupture and ipsilateral knee osteoarthritis. The advantage of using computer navigation with an extramedullary femoral jig can lead to improved accuracy of bone cuts, which is important in the presence of anatomical disruption. Chronic failures of the extensor mechanism require different approaches depending on the inherent and underlying pathology. We feel that the multidisciplinary team approach to the management and use of two surgeons with differing expertise added to the successful outcome of this complex case.

Reconstruction of the extensor mechanism augmented with reverse transferred iliotibial band after proximal tibia tumor resection and mega-prosthetic replacement

BACKGROUND

The optimal procedure for functional reconstruction of the extensor mechanism after proximal tibia mega-prosthetic replacement remains unclear.

METHODS

Since 2006, 14 consecutive patients with aggressive bone tumors in the proximal tibia who underwent mega-prosthetic replacement were prospectively treated with reconstruction of the extensor mechanism using an ipsilateral iliotibial band. The surgical procedure consisted of wrapping the reversed iliotibial band around the tibia component, firmly suturing it to the remaining patellar tendon and tibialis anterior fascia, and covering it with a muscle flap. At the last follow up, the function was assessed based on extensor lag, active flexion of the knee, and Musculoskeletal Tumor Society score. Patellar height was measured with the Insall-Salvati ratio (ISR) preoperatively, postoperatively, and at the last follow up.

RESULTS

At the last follow up, the extensor lag and active flexion in 14 patients averaged 2.5° and 86°, respectively. Musculoskeletal Tumor Society score could be obtained in nine surviving patients at the last follow up and was a mean of 20.7 points. The mean ISR preoperatively, postoperatively, and at the last follow up was 1.04, 0.75, and 0.89, respectively. The extensor lag was not associated with the ISR value at any points, while reduced active flexion significantly correlated with a low ISR at the last follow up (P = 0.015). Four patients underwent additional surgeries due to postoperative infection, but none required eventual revision or amputation.

CONCLUSION

The extensor mechanism reconstruction with the reverse transferred iliotibial band for mega-prosthetic replacement after proximal tibia resection yielded reliable outcomes with functional benefit to stabilize active knee extension.

Soft tissue extensor mechanism tendon ruptures of the knee

Ruptures of the extensor mechanism of the knee are serious injuries requiring prompt diagnosis and treatment. They can be divided into soft tissue and bony causes. Soft tissue tendon injuries can be either partial or complete. Rupture of the quadriceps tendon is an uncommon injury and is more frequent in patients over the age of 40 years. Patella tendon ruptures are even rarer and are more frequent in patients under the age of 40 years. Causes can be direct or indirect. Complete ruptures of the quadriceps tendon or patella tendon benefit from early surgical management, while partial ruptures may be managed non-operatively. This article gives an overview of the presentation, assessment and management of soft tissue extensor mechanism tendon ruptures for core surgical, acute care common stem and emergency medicine trainees.

Considerations in spontaneous quadriceps tendon rupture repair in end-stage renal disease patients: A case report

INTRODUCTION

Spontaneous quadriceps tendon rupture (SQTR) is a rare injury to the knee extensor mechanism that is usually associated with systemic diseases such as end stage renal diseases (ESRD) and it is more prevalent in the elderly. Due to the underlying pathology, quadriceps tendon rupture warrants special considerations and management in its repair.

CASE REPORT

We present two cases of quadriceps tendon rupture in end-stage renal disease (ESRD) patients. The first case; a 57 years old female who had bilateral SQTR and is undergoing hemodialysis. The second patient, a 26 years old male had unilateral quadriceps tendon rupture caused by minimal trauma. The first patient had a trans-osseous repair by direct suturing the quadriceps tendon stump to the proximal pole patella. The second patient was repaired with a modified Bunnel suture and anchor placement on the proximal pole patella. The first case had a re-rupture of the right quadriceps tendon and the second case has recovered with improved outcomes.

DISCUSSION

Spontaneous quadriceps tendon rupture is usually underlined by degenerative changes of the tendons. Special care is needed to address the pathologic tendon underlying SQTR. The current surgical literature still lacks the statistical data that shows which surgical approach is most optimal for SQTR in ESRD patients.

CONCLUSION

SQTR rupture is generally an injury of brittle tendons caused by underlying diseases. A multidisciplinary and comprehensive approach including a proper surgical approach and postoperative managements are crucial for good functional outcomes of the extensor mechanism.

Evaluation of recurrent dislocation of the patella in children with MRI: Goldthwait technique combined with lateral release, and VMO advancement-a retrospective study of 85 knees

PURPOSE

There are certain risk factors responsible for patella instability that should be identified before choosing the most appropriate treatment.

METHODS

We evaluated 83 skeletally immature patients who, after two or more patellar dislocation episodes, underwent surgical treatment to address the condition of patellar instability. Each patient was evaluated for patellar instability risk factors using the Balcarek patellar instability severity score. Evaluation of patellar instability included knee MRI to systematically identify anatomical risk factors. The preoperative and postoperative clinical evaluation included the modified Cincinnati score and the Kujala score. The Roux-Goldthwait technique combined with lateral retinaculum release and the advancement of the vastus medialis oblique (VMO) was performed on all knees.

RESULTS

The mean patient age at the time of surgery was 12.2 ± 1.59 years (range 8-14 years). The average follow-up was 4.72 ± 1.37 (range 3-8) years. Trochlear dysplasia (decreased trochlear depth), the most common anatomical risk factor, was identified in 71 knees (83.5%). The modified Cincinnati score increased from 58.46 ± 8.75 (range 49-76) points to 94.07 ± 2.88 (range 88-98) postoperatively. The mean Kujala scores increased from 58.51 ± 8.94 (range 49-76) points to 93.66 ± 2.65 (range 87-98) postoperatively. The two-tailed P value was less than 0.0001. The patients were followed until their skeletal maturation, without reporting any incidents of patella dislocation, except one.

CONCLUSION

The Roux-Goldthwait technique combined with lateral retinaculum release, and the advancement of VMO, can restore patellar tracking and can decrease the probability of another dislocation. It was an effective treatment in skeletally immature patients who had two or more episodes of patellar dislocation.

LEVEL OF EVIDENCE

IV.

Three-dimensional-printed custom-made patellar endoprosthesis for recurrent giant cell tumor of the patella: A case report and review of the literature

BACKGROUND

Giant cell tumor (GCT) is a benign lesion and rarely involves the patella. This disease is characterized by a relatively high recurrence rate after primary treatment. En bloc resection has been a predominant option for recurrent GCT. However, total patellectomy can lead to disruption of the knee. Therefore, exploration of functional reconstruction of the extensor mechanism is worthwhile.

CASE SUMMARY

A 54-year-old woman presented with right knee pain and swelling, and was diagnosed as having a GCT in the patella following curettage and autograft. Medical imaging revealed a lytic and expanded lesion involving the whole patella with focal cortical breaches and pathological fracture. Based on the combination of histological, radiological, and clinical features, a diagnosis of recurrent GCT in the patella was made (Campanacci grade III). After a multidisciplinary team discussion, three-dimensional (3D)-printed custom-made patellar endoprosthesis was performed following en bloc resection for reconstructing the extensor mechanism. The patient was followed for 35 mo postoperatively. No evidence of local recurrence, pulmonary metastasis, or osteoarthritis of the right knee was observed. The active flexion arc was 0°-120°, and no extension lag was detected. A favorable patellar tracking and height (Insall-Salvati ratio 0.93) were detected by radiography.

CONCLUSION

We depict a case of a GCT at the right patella, which was successfully treated by patellectomy and 3D-printed custom-made endoprosthetic replacement. The patella normal reconstruction, the precise-fit articular design, and gastrocnemius flap augmentation could lead to satisfactory knee function and a low rate of complications in the short-term follow-up.

Successful mid- to long-term outcome after reconstruction of the extensor apparatus using proximal tibia-patellar tendon composite allograft

PURPOSE

The purpose of the study was to assess the outcomes of extensor mechanism reconstruction with proximal tibia-patellar tendon composite allograft.

METHODS

24 consecutive patients treated with allograft-prosthetic composite for proximal tibia tumour resection and a conventional total knee arthroplasty were included. Extensor mechanism reconstruction was performed with a proximal tibia-patellar tendon composite allograft and the suture of the donor tendon to the remnant native patellar tendon. Function was evaluated by the Musculoskeletal Tumor Society score (MSTS) and range of motion. Western Ontario and MacMaster University (WOMAC) and visual analogue scale for pain also were used.

RESULTS

After a mean follow-up of 11.7 (range 3-15) years, mean MSTS score was 22.4 (range 20-30), mean flexion was 94.0° (range 84°-110°), and mean extension lag was 7.2° (range 0°-18°). The mean VAS-pain was 4.3 (range 2-6), and WOMAC score was 72.4 (range 58-100). There was no failure of the reconstructed extensor mechanism.

CONCLUSION

Patellar tendon reconstruction with allogeneic tissue from the proximal tibia allograft sutured to the recipient's remnant patellar tendon provides the mechanical support needed for healing of the reconstructed extensor mechanism with a substantial functional benefit to stabilize active knee extension and successful reconstruction survival at long-term.

LEVEL OF EVIDENCE

III.

Quads or quins? Atraumatic restricted knee flexion due to accessory quadriceps bands in children

BACKGROUND

Recent anatomical investigations have emphasized the variability in the knee extensor apparatus, with particular attention to a fifth component of the quadriceps femoris termed the tensor vastus intermedius or accessory "quinticeps femoris." Disorders of this structure have not been described in the pediatric imaging literature.

OBJECTIVE

To review the clinical features, pathoanatomy and imaging findings of children presenting with derangement of the accessory quadriceps femoris, with a particular emphasis on the utility of early magnetic resonance imaging (MRI) of the thigh.

MATERIALS AND METHODS

This is a retrospective analysis of 3 children, ages 3-10 years at presentation, who underwent imaging evaluation with subsequent surgically proven accessory quadriceps femoris muscles. Their clinical histories, including duration of symptoms, MRI findings, intervention and surgical outcomes, are reported.

RESULTS

All patients presented with progressive unilateral restricted knee flexion and had multiple imaging studies targeting the knee before diagnosis. Diagnosis in all patients was made on MRI of the thighs, which demonstrated a fusiform low signal intensity structure with muscle-like architecture arising from the anterior or anterolateral proximal femur and blending with the common quadriceps tendon distally. All patients underwent surgical release of the anomalous band with significant functional improvement.

CONCLUSION

In cases of progressive limited knee flexion without intrinsic pathology, an accessory quadriceps muscle should be considered as an extrinsic cause. Our experience demonstrated this to be readily identifiable on MRI, with symptomatic improvement following surgical release. Early recognition of this condition should prevent unnecessary intervention such as knee arthroscopy and the debilitating loss of flexion due to delayed diagnosis.

The extensor efficiency of unicompartmental, bicompartmental, and total knee arthroplasty

Aims

Unicompartmental knee arthroplasty (UKA) and bicompartmental knee arthroplasty (BCA) have been associated with improved functional outcomes compared to total knee arthroplasty (TKA) in suitable patients, although the reason is poorly understood. The aim of this study was to measure how the different arthroplasties affect knee extensor function.

Methods

Extensor function was measured for 16 cadaveric knees and then retested following the different arthroplasties. Eight knees underwent medial UKA then BCA, then posterior-cruciate retaining TKA, and eight underwent the lateral equivalents then TKA. Extensor efficiency was calculated for ranges of knee flexion associated with common activities of daily living. Data were analyzed with repeated measures analysis of variance (α = 0.05).

Results

Compared to native, there were no reductions in either extension moment or efficiency following UKA. Conversion to BCA resulted in a small decrease in extension moment between 70° and 90° flexion (p < 0.05), but when examined in the context of daily activity ranges of flexion, extensor efficiency was largely unaffected. Following TKA, large decreases in extension moment were measured at low knee flexion angles (p < 0.05), resulting in 12% to 43% reductions in extensor efficiency for the daily activity ranges.

Conclusion

This cadaveric study found that TKA resulted in inferior extensor function compared to UKA and BCA. This may, in part, help explain the reported differences in function and satisfaction differences between partial and total knee arthroplasty.

Cite this article: Bone Joint Res 2021;10(1):1–9.

Patellar tendon reconstruction with hamstring autograft for the treatment of chronic irreparable patellar tendon injuries

BACKGROUND

Patellar tendon injuries not amenable to primary repair present a challenging problem for surgeons and patients alike. No standard surgical technique exists for these injuries and few studies report outcomes after surgical treatment.

METHODS

A retrospective analysis was conducted for patients undergoing surgical treatment for irreparable patellar tendon tears. Patients were treated with an indirect tendon reconstruction technique using high-strength suture to set initial patellar height and hamstring autograft for biologic augmentation. Patients who underwent this procedure between 2012 and 2018 and met minimum two-year follow-up with completion of all outcome measurements including KOOS, PROMIS, VAS pain and satisfaction scores were included.

RESULTS

Eleven patients met inclusion criteria. Ten of eleven patients (91%) had intact repairs and final patient outcomes were collected at a mean of 54.9 ± 23.1 months after surgery. Only one patient experienced extensor lag at final follow-up (p < 0.001). The preoperative Caton-Dechamps ratio was 1.77 ± 0.58, which decreased to 0.98 ± 0.25 after surgery (p < 0.001). The mean postoperative KOOS ADL score was 61.5. The mean postoperative PROMIS Global Mental and Physical Health scores were 46.9 ± 8.7 and 42.0 ± 9.8. Post-operative mean VAS satisfaction score was 5.6 ± 3.4.

CONCLUSIONS

Patellar tendon reconstruction with autologous hamstring tendon graft and suture augmentation allows for acceptable outcomes in the setting of patellar tendon disruption with segmental defects when direct repair is not possible.

Early complications and causes of revision after rotating-hinge TKA

INTRODUCTION

The use of rotating-hinge total knee arthroplasties (TKA), despite several developments in prosthetic design, remains controversial. Results as well as indications of these devices are still discussed in primary intention and for young patients. The aim was to analyze early complications and survival rate of rotating-hinge TKA in primary intention and for revisions.

METHODS

A retrospective study included all the patients operated for primary or revision TKA procedure using a rotating-hinge TKA between 2015 and 2018. Clinical and radiological data were collected before surgery and then at a minimum follow-up of 1 year. The primary endpoint was the aseptic revision-free survival rate. Secondary endpoints were the overall survival rate, IKS scores, range of motion and patellar complications.

RESULTS

Forty patients were included at an average follow-up of 18 months. Primary implantation was performed for 12 patients (30%), and revision for 28 cases (70%). At a mean follow-up of 18 months, only one implant was removed for a septic cause. The cumulative survival rate at 24 months was 95%. At final review, eight knees (20%) had been revised, five (12.5%) due to infection, two (5%) because of extensor mechanism failure, two (5%) for global stiffness. The objective and subjective IKS were significantly higher postoperatively in both primary and revision groups (p < 0.0001). Patellar height was significantly smaller after revision (p = 0.04), while ROM significantly improved in this group (p = 0.02). At final endpoint, one implant was removed for a septic cause.

CONCLUSION

This rotating-hinge TKA provides satisfying clinical and functional outcomes in primary intentions and in revision cases. There was no implant-associated complication. The complication rate remains high for revision surgery cases, mostly due to previous joint infections and poor soft tissue quality causing extensor mechanism failure. A longer-term study should be conducted to confirm this trend.

Extensor mechanism reconstruction with peroneus longus tendon autograft for neglected patellar fracture, report of 2 cases

Extensor mechanism deficiency in the knee may occur due to neglected patellar and quadriceps tendons rupture or may be caused by chronic fractures of the patella. Older patients can tolerate nonunion with impaired function including extension limitation or persistent muscle weakness. In young patients, performing rigid internal fixation with reoperation should be considered when a nonunion occurs. However, delayed and neglected nonunion in patella fractures require performing different surgical procedures. We report two cases, operated for a patella fracture, in whom nonunion occurred and accompanied by patellar migration and retraction of quadriceps tendon because of a fixation failure. We reconstructed the extensor mechanism with peroneus longus tendon autograft and, owing to this method, we achieved excellent functional results during a 2-year follow-up period.

Surgical management of patellofemoral instability part 2: post-operative imaging

The patellofemoral joint is a complex joint requiring contributions from both bone and soft tissue for its stability. Pathology of the patellofemoral joint manifests as instability or anterior knee pain. Careful clinical and imaging assessment is important for managing these patients with cross-sectional imaging being a vital component in pre-surgical planning. Operative treatment can involve soft tissue procedures, bony procedures or both. The purpose of part 2 of this two-part article is to review the post-operative imaging findings of the knee extensor mechanism. In doing so, we will provide an overview of some of the bony and soft tissue procedures performed with details of their indications and possible complications. An appreciation of the post-operative surgical appearances will ensure a more comprehensive report and can prevent misinterpretation by the radiologist.

Patellar tendon buckling in post-operative total knee arthroplasty patients is more prominent than in healthy controls

Recent evidence suggests the patellar tendon undergoes buckling during normal knee flexion, which likely contributes to the functioning of the extensor mechanism. Thus, evaluating buckling in patients following total knee arthroplasty (TKA), where extensor mechanism dysfunction remains a common complication, may be relevant. The study goals were to identify whether post-TKA patients exhibit differences in patellar tendon buckling from healthy, similarly-aged adults and whether such buckling correlates with knee and patellar tendon health. Patellar tendon buckling was assessed during passive knee flexion using ultrasound in post-TKA patients (n = 20; 12M, 68 ± 8 years) and compared with previously reported data from healthy adults (n = 12; 12M; 70 ± 8 years). Patients exhibited significantly larger (p < 0.01) buckling magnitude and angles than healthy adults, and reduced distal buckling was linked with better Knee Society Scores (p = 0.04, R² = 0.24). The greater patellar tendon buckling observed in post-TKA patients could arise due to factors related to the surgery itself (e.g. infrapatellar fat pad resection) or it may be that post-TKA patients had greater patellar tendon buckling before their procedure. Alterations in patellar tendon buckling may predispose individuals to post-surgical complications including instability, anterior knee pain, and extensor mechanism dysfunction, with further work necessary to elucidate potential links.

Surgical management of patellofemoral instability. I. Imaging considerations

The patellofemoral joint is a complex joint that relies on both bone and soft tissues for its stability. Dysfunction of the patellofemoral joint, whether pain or instability, is a common cause of medial consultation. Thorough clinical and imaging assessment is important for managing these patients, who may require a combination of a bony and soft tissue surgical procedure. Trochlear dysplasia, a cause of anterior knee pain and patellar instability, has been classified using conventional radiography. Radiographic signs on a lateral projection, such as the "double contour" sign and the "crossing sign", can alert the radiologist to the grade of trochlear dysplasia. Magnetic resonance imaging (MRI) is the gold standard for accurately assessing the soft tissue around the patellofemoral joint, such as the medial patellofemoral ligament and the medial and lateral patella retinacula, especially in the context of a transient patella dislocation. Risk factors for patellofemoral instability, such as patella alta, an increased tibial tubercle to trochlear groove distance and trochlear dysplasia, can all be assessed on MRI. Advanced imaging techniques such as dynamic MRI and CT are able to demonstrate patellar maltracking. These techniques can also be employed to reliably assess the outcomes of treatment. In this article, we review the normal and abnormal pre-operative imaging findings of the knee extensor mechanism in relation to patellofemoral joint instability. This review provides a useful tool for the reporting radiologist and highlights the imaging findings that are of relevance to the orthopaedic surgeon.

Early pre-radiographic structural pathology precedes the onset of accelerated knee osteoarthritis

BACKGROUND

Accelerated knee osteoarthritis (AKOA) is characterized by more pain, impaired physical function, and greater likelihood to receive a joint replacement compared to individuals who develop the typical gradual onset of disease. Prognostic tools are needed to determine which structural pathologies precede the development of AKOA compared to individuals without AKOA. Therefore, the purpose of this manuscript was to determine which pre-radiographic structural features precede the development of AKOA.

METHODS

The sample comprised participants in the Osteoarthritis Initiative (OAI) who had at least one radiographically normal knee at baseline (Kellgren-Lawrence [KL] grade < 1). Participants were classified into 2 groups based on radiographic progression from baseline to 48 months: AKOA (KL grade change from < 1 to > 3) and No AKOA. The index visit was the study visit when participants met criteria for AKOA or a matched timepoint for those who did not develop AKOA. Magnetic resonance (MR) images were assessed for 12 structural features at the OAI baseline, and 1 and 2 years prior to the index visit. Separate logistic regression models (i.e. OAI baseline, 1 and 2 years prior) were used to determine which pre-radiographic structural features were more likely to antedate the development of AKOA compared to individuals not developing AKOA.

RESULTS

At the OAI baseline visit, degenerative cruciate ligaments (Odds Ratio [OR] = 2.2, 95% Confidence Interval [CI] = 1.3,3.5), infrapatellar fat pad signal intensity alteration (OR = 2.0, 95%CI = 1.2,3.2), medial/lateral meniscal pathology (OR = 2.1/2.4, 95%CI = 1.3,3.4/1.5,3.8), and greater quantitative knee effusion-synovitis (OR = 2.2, 95%CI = 1.4,3.4) were more likely to antedate the development of AKOA when compared to those that did not develop AKOA. These results were similar at one and two years prior to disease onset. Additionally, medial meniscus extrusion at one year prior to disease onset (OR = 3.5, 95%CI = 2.1,6.0) increased the likelihood of developing AKOA.

CONCLUSIONS

Early ligamentous degeneration, effusion/synovitis, and meniscal pathology precede the onset of AKOA and may be prognostic biomarkers.

The role of mesh technology with tumor prosthesis reconstruction to reconstruct the extensor mechanism of knee joint after resection of proximal tibial tumors

PURPOSE

The aim of this study was to evaluate the role of mesh technique in the reconstruction of the extensor mechanism after resection of proximal tibial tumors.

METHODS

We retrospectively analyzed the cases of 14 patients who were diagnosed with proximal tibial tumors at our center and reconstructed with tumor prosthesis, gastrocnemius muscle, and mesh between 2012 and 2017. The treatment strategies for patellar tendon reconstruction primarily involve gastrocnemius reconstruction to cover the tumor prosthesis and mesh reconstruction for the patellar ligament.

RESULTS

Among the 14 patients, the mean was 1.57° (range 0-12°) for active extension versus 105.00° (range 80-120°) for active flexion. The mean for passive extension was 0°. The passive flexion mean was 115.00° (range 90-120°). The extensor lag averaged 1.57° (range 0-12°), and the mean Musculoskeletal Tumor Society score (MSTS) was 23.57 (range 19-27). The average follow-up for all patients was 23.50 months (range 14-37). During the recent follow-up, all patients were able to walk without crutches. Two patients underwent above-the-knee amputation for local recurrence of the tumor, and lung metastasis occurred in three patients after operation. There were no postoperative complications.

CONCLUSIONS

Extensor lag was remarkably reduced in the surgery group in comparison to previous study reports. Surgical resection is a simple, reliable, and effective method to remove and control the tumor. Mesh reconstruction of patellar ligament is effective to reconstruct the extensor mechanism of the knee after excision of tumor.

Surgical options for chronic patellar tendon rupture in total knee arthroplasty

PURPOSE

The purpose of this study was to compare mid-term results of three different reconstructive techniques for chronic patellar tendon disruption after total knee arthroplasty (TKA). Several surgical techniques have been proposed, but to date it is still unclear which is the best solution. The hypothesis was that allografts provide better functional results than autografts in restoring a correct joint function.

METHODS

Twenty-one reconstructions were performed in twenty-one patients (three groups of seven patients) with chronic patellar tendon lesion following TKA. Group I underwent reconstruction with an Achilles tendon allograft with a calcaneal block, Group II with an autograft of the quadriceps tendon reinforced by the semitendinosus tendon and Group III with a full extensor mechanism allograft consisting of the tibial tubercle, patellar tendon, patella, and quadriceps tendon. Preoperatively and at each follow-up, the value of the extensor lag and the Knee Score (KS) were recorded.

RESULTS

The mean extensor lag decreased from 50° ± 19.4° to 3° ± 1.6°. The KSS improved from 44.7 ± 20.5 to 78.9 ± 13.6 points. The comparison between the groups showed statistically significant differences in the mean postoperative KS between Groups I (average score of 87.7 ± 14.3 points) and II (average score of 70 ± 4.1 points), but not between Groups I and III (average score of 78.9 ± 14.6 points) or between Groups II and III. Differences in the postoperative extensor lag were not significant between the three groups.

CONCLUSIONS

The present study may serve surgeons in choosing the best reconstructive strategy for a chronic patellar tendon lesion in TKA. According to the reported results, an Achilles tendon allograft should be considered the gold standard repair. The autograft technique is suitable when the host tissue is competent, particularly when dealing with younger patients or post-infection. A full extensor mechanism allograft may represent a reliable solution when the defect involves the patellar bone or the quadriceps tendon.

LEVEL OF EVIDENCE

IV.

Tumour endoprosthesis replacement in the proximal tibia after intra-articular knee resection in patients with sarcoma and recurrent giant cell tumour

PURPOSE

Proximal tibia replacements are commonly associated with post-operative complications and poor functional results due to an insufficiency of the extensor mechanism.

METHODS

This study evaluated the clinical results with a special emphasis of the extensor mechanism reconstruction with a reattachment tube and complications after intra-articular resection of the proximal tibia and reconstruction with a tumour endoprosthesis (MUTARS®) in 98 patients (median age 18 years) with malignant bone tumours or giant cell tumours.

RESULTS

Kaplan-Meier analysis showed that the limb survival rates were 94.9, 90.5 and 74.5% at one, two and ten years, respectively. Periprosthetic infection was the most common reason for secondary amputation (eight patients). The cumulative incidence rates of prosthetic failure (Henderson II-IV) were 18% at two years and 29% at five years post-operatively. An active extension deficit of more than 10° was noted in six patients only.

CONCLUSIONS

These results suggest that limb salvage with tumour prostheses after intra-articular resection can achieve good functional results with an active extension of the knee in the majority of patients. While mechanical complications can be treated successfully with revision surgery, periprosthetic infection continues to be the main reason for secondary amputation.

Intersegmental kinetics significantly impact mapping from finger musculotendon forces to fingertip forces

Predicting the fingertip force vector resulting from excitation of a given muscle remains a challenging but essential task in finger biomechanical modeling. While the conversion of musculotendon force to fingertip force can significantly be affected by finger posture, current techniques utilizing geometric moment arms may not capture such complex postural effects. Here, we attempted to elucidate the postural effects on the mapping between musculotendon force and fingertip force through in vitro experiments. Computer-controlled tendon loading was implemented on the 7 index finger musculotendons of 5 fresh-frozen cadaveric hands across different postures. The resulting fingertip forces/moments were used to compute the effective static moment arm (ESMA), relating tendon force to joint torque, at each joint. The ESMAs were subsequently modeled in three different manners: independent of joint angle; dependent only upon the corresponding joint angle; or dependent upon all joint angles. We found that, for the reconstruction of the fingertip force vector, the multi-joint ESMA model yielded the best outcome, both in terms of direction and magnitude of the vector (mean reconstruction error <4° in direction and <2% in the magnitude), which indicates that intersegmental force transmission through a joint is affected by the posture of neighboring joints. Interestingly, the ESMA model that considers geometric changes of individual joints, the standard model used in biomechanical stimulations, often yielded worse reconstruction results than the simple constant-value ESMA model. Our results emphasize the importance of accurate description of the multi-joint dependency of the conversion of tendon force to joint moment for proper prediction of fingertip force direction.

A classification-based approach to the patella in revision total knee arthroplasty

Background

There is a paucity of data to guide management of the patella in revision total knee arthroplasty (RTKA). The purpose of this study was to review our experience with patellar management in RTKA.

Methods

We retrospectively reviewed 422 consecutive RTKAs at a minimum of 2 years (mean, 42 months). Patellar management was guided by a classification that considered stability, size, and position of the implanted patellar component, thickness/quality of remaining bone stock, and extensor mechanism competence.

Results

Management in 304 aseptic revisions included retention of a well-fixed component in 212 (69.7%) and revision using an all-polyethylene component in 46 (15.1%). Patella-related complications included 5 extensor mechanism ruptures (1.6%), 3 cases of patellar maltracking (1.0%), and 2 periprosthetic patellar fractures (0.7%). Of 118 2-stage revisions for infection, an all-polyethylene component was used in 88 (74.6%), patelloplasty in 20 (16.9%), and patellectomy in 7 (5.9%). Patella-related complications included 4 cases of patellar maltracking (3.4%), 3 extensor mechanism ruptures (2.5%), and 1 periprosthetic patellar fracture (0.8%).

Conclusions

Septic revisions required concomitant lateral releases more frequently (38.1% vs 10.9%; P < .02) but had a similar rate of patellar complications (6.8% vs 3.3%; P = .40). No cases required rerevision specifically for failure of the patellar component. Patients who had a patelloplasty had worse postoperative Knee Society functional scores than those with a retained or revised patellar component. In most aseptic RTKAs, a well-fixed patellar component can be retained. If revision is required, a standard polyethylene component is sufficient in most septic and aseptic revisions. Rerevisions related to the patellar component are infrequent.

The biomechanical model of the long finger extensor mechanism and its parametric identification

The extensor mechanism of the finger is a structure transmitting the forces from several muscles to the finger joints. Force transmission in the extensor mechanism is usually modeled by equations with constant coefficients which are determined experimentally only for finger extension posture. However, the coefficient values change with finger flexion because of the extensor mechanism deformation. This induces inaccurate results for any other finger postures. We proposed a biomechanical model of the extensor mechanism represented as elastic strings. The model includes the main tendons and ligaments. The parametric identification of the model in extension posture was performed to match the distribution of the forces among the tendons to experimental data. The parametrized model was used to simulate three degrees of flexion. Furthermore, the ability of the model to reproduce how the force distribution in simulated extensor mechanism changes according to the muscle forces was also demonstrated. The proposed model could be used to simulate the extensor mechanism for any physiological finger posture for which the coefficients involved in the equations are unknown.

Patellar tendon reconstruction using an extended gastrocnemius flap following cryogenic injury to the knee

Cryogenic thermal necrosis after knee surgery is rare. We describe a patient who presented with an anterior knee soft tissue defect in conjunction with an extensor mechanism deficiency secondary to a cold thermal injury after an anterior cruciate ligament reconstruction. We treated the patient with a single stage surgical procedure combining patellar tendon reconstruction and soft tissue coverage utilizing the superficial portion of the patient's vascularized Achilles tendon attached to a medial gastrocnemius flap. The patient returned to unrestricted activities and has demonstrated this through a five year follow-up.

The effect of the extensor mechanism on maximum isometric fingertip forces: A numerical study on the index finger

The extensor mechanism is a tendinous network connecting intrinsic and extrinsic muscles of the finger and its function has not yet been fully understood. The goal of this study was to assess the effect of the extensor mechanism on the maximum isometric fingertip forces - a parameter which is essential for grasping. For this purpose, maximum fingertip forces in all directions (i.e. feasible force sets) of two musculoskeletal models of the index finger were compared: the wEM model included a full representation of the extensor mechanism, whereas in the noEM model the extensor mechanism was replaced by a single extensor tendon without connectivity to intrinsic muscles. The feasible force sets were computed in the flexion-extension plane for nine postures. Forces in four predefined directions (palmar, proximal, dorsal, and distal), and the peak resultant forces were evaluated. Averaged forces in all four predefined directions were considerably larger in the wEM model (+187.6%). However, peak resultant forces were slightly lower in the wEM model (-4.3% on average). The general advantage of the wEM model could be explained by co-contraction of intrinsic and extrinsic extensor muscles which allowed reaching larger activation levels of the extrinsic flexors. Only within a narrow range of force directions the co-contraction of intrinsic muscles limited the fingertip forces and lead to lower peak resultant forces in the wEM model. Rather than maximizing peak resultant forces, it appears that the extensor mechanism is a sophisticated tool for increasing maximum fingertip forces over a broad range of postures and force directions - making the finger more versatile during grasping.

Adult native knee extensor mechanism ruptures

Extensor mechanism rupture is a serious event requiring prompt diagnosis and treatment. Patella fractures are reportedly six times more frequent than soft tissue injuries such as quadriceps or patella tendon ruptures. Classically quadriceps and patella tendon ruptures are seen more in males, with those over 40 predominantly suffering from quadriceps tendon ruptures, often associated with an underlying condition, whereas patella tendon ruptures are mostly associated with sport injuries and are commonly seen in the under 40s. Almost all types of extensor mechanism ruptures benefit from early management which typically involves surgery. Diagnosis can be deemed easy to make by demonstrating inability to actively extend the knee, this however can be easily overlooked and missed in a busy emergency department leading to a late diagnosis and necessitating more complex surgery. Earlier surgical intervention and rehabilitation tend to produce improved outcomes.

Bilateral patellar tendon reconstruction using LARS ligaments: case report and review of the literature

Background

Acute bilateral patellar tendon rupture is a rare occurrence, with only 1 case reported in the English literature of a young, fit athlete with no regular medications. To our knowledge this is the first such case reported using a LARS reconstruction.

Case presentation

A 26-year-old otherwise well ex-olympic gymnast with bilateral acute on chronic patellar tendon rupture underwent reconstruction using LARS ligaments. At four years post-operatively he has maintained full range of motion and strength, without re-rupture or any evidence of synovitis.

Conclusion

The use of LARS ligament for reconstruction of the patellar tendon is a viable and effective option for rupture. It avoids donor site morbidity associated with autograft. Reconstruction of both patellar tendons simultaneously in a young, elite-level athlete has not previously been reported in the English-language literature.

Polypropylene mesh augmentation for complete quadriceps rupture after total knee arthroplasty

INTRODUCTION

Polypropylene mesh has previously been shown to be an effective treatment for failed patellar tendon repairs after total knee arthroplasty (TKA), but there have been few reports of this synthetic mesh used in complete quadriceps rupture after TKA.

METHODS

We retrospectively reviewed seven consecutive cases in six patients with complete quadriceps tears after TKA who had their quadriceps tendon repaired with suture and polypropylene mesh augmentation. All but two patients had previously failed primary suture repair. Patient outcomes were evaluated using the Knee Society Score. Standardized anterior-posterior (AP), lateral and merchant radiographs were evaluated preoperatively and at final follow-up.

RESULTS

Seven knees in six patients were evaluated with a mean follow-up of 34±10 (range 24 to 49months) months. There were only four clinical successes defined as an extensor lag less than 30°. Of the functioning knees at final follow-up (n=5) the overall extensor lag in this group did significantly improve from 50±13° to 20±15° (range 5 to 40°) (p=.01). Mean postoperative flexion at final follow-up was 115±8°. Mean Knee Society Score for function improved from 20±30 to 45±54 (p=.03) as did the mean Knee Society Score for pain (44±18 vs. 74±78, p=.02).

DISCUSSION

Polypropylene mesh offered limited postoperative functional results when used as an augment to the multiply operated knee that sustains a complete quadriceps rupture after TKA, but did allow for significant improvement in postoperative pain outcomes.

LEVEL OF EVIDENCE

IV.

Surgical Management of Patellar Fractures

The patella plays a crucial role in the extensor mechanism to increase the mechanical advantage of the quadriceps. Fractures can be classified based on displacement, comminution, and fracture pattern, which often guide treatment. Modern treatment options include internal fixation using tension bands with Kirschner wires or cannulated screws, lag screw fixation, partial patellectomy, and rarely total patellectomy. Nondisplaced, closed patellar fractures or fractures with less than 2-mm articular steps can be successfully treated conservatively. Open fractures, articular step of 2 mm or greater, and loss of knee extension are indications for surgical intervention.

The hemisoleus rotational flap provides a novel superior autograft reconstructive option for the treatment of chronic extensor mechanism disruption

Chronic disruption of the extensor mechanism is a devastating problem after total knee arthroplasty. Quadriceps tendon ruptures occur at an estimated 0.1% prevalence in the setting of total knee arthroplasty. Complete tears of the quadriceps tendon generally have poor results and high rates of rerupture. We present a case of a quadriceps tendon rupture after total knee arthroplasty which reruptured after initial direct repair. The patient presented to us with a chronically retracted rerupture and was subsequently reconstructed successfully with a novel extended medial gastrocnemius-soleus-calcaneus local rotational pedicle flap.

Complications involving the extensor mechanism after total knee arthroplasty

PURPOSE

To overview the complications involving extensor apparatus of the knee following total knee arthroplasty (TKA) and to summarize which are the lines of treatment available and their reported outcomes in literature.

METHODS

A comprehensive search of several databases was performed using as basic keywords "complications after TKA", "extensor mechanism disruption", "periprosthetic patellar fracture", "quadriceps tendon rupture", "quadriceps tendon rupture" isolated or combined with other terms by using Boolean operators. The methodological quality of each article was also evaluated using the Coleman methodology score (CMS).

RESULTS

Twenty-nine studies were evaluated. The mean CMS of the studies selected was 33.1/100. Patellar fractures, requiring surgical treatment when there is rupture of the extensor mechanism or loosening of the patellar component, were treated surgically in 28.1 % of patients. The patellar and quadriceps tendon ruptures were surgically treated with reconstruction or augmented repair, respectively, in 98.6 and 76.5 %.

CONCLUSION

Complications involving the extensor apparatus of the knee following a TKA need early and appropriate management to avoid their devastating influence on joint functionality. Management has to be evaluated very carefully based on the site of the lesion, integrity of the prosthetic components and surrounding tissue to restore, and the patients' individual characteristics. The surgical approach for comminuted periprosthetic fractures and reconstruction of torn tendons of the extensor apparatus are needed to restore function and decrease pain, but, given the poor methodological quality of the studies published so far, it is not clear which surgical technique or graft leads to better outcomes. Therefore, there is an absolute need for better designed comparative trials producing clearer and stronger evidence on this critical matter.

LEVEL OF EVIDENCE

IV.

A new technique using mesh for extensor reconstruction after proximal tibial resection

BACKGROUND

Proximal tibial reconstruction following wide resection in both malignant and benign tumors presents difficulties mainly due to both patellar tendon reconstruction and high risk of infection. The purpose of this study is to determine the efficacy of a new technique using a mesh for extensor reconstruction.

METHODS

We retrospectively reviewed nine consecutive patients who underwent resection of the proximal tibia with prosthetic reconstruction and reconstruction of the extensor using a mesh between 2009 and 2012. The surgical technique included the attachment of the mesh to the tibial component with a band of meshes looped over the patella and a gastrocnemius flap for coverage.

RESULTS

One patient had an above-the-knee amputation due to infection. Eight patients were followed up for 33 months (range, 20-50). In the eight patients, extensor lag had a mean of 5° (range, 0 to 20). Active flexion had a mean of 96.25° (range, 80 to 120) and ISOLS scores had a mean of 21/30 (range, 18 to 26). All patients were able to ambulate without crutches at the latest follow-up.

CONCLUSION

Extensor lag was significantly less compared to previous reports. No complications were observed in eight patients. Utilization of the mesh for extensor reconstruction after the proximal tibial resection is a simple, reliable and successful method.

Extra-articular step osteotomy of the olecranon: A biomechanical assessment

BACKGROUND

Trans-olecranon chevron osteotomies (COs) remain the gold standard surgical approach to type C fractures of the distal humerus. This technique is associated with a high complication rate and development of an extra-articular olecranon osteotomy may be advantageous. The aim of this study was to compare the load to failure of COs with extra-articular oblique osteotomies (OOs) as well as modified, extra-articular step osteotomies (SOs).

METHODS

These three osteotomies and their subsequent fixation utilizing a standardized tension band wiring technique were tested in 42 composite analog ulnae models at 20° and 70° of flexion. Triceps loading was simulated with a servo hydraulic testing machine. All specimens were isometrically loaded until failure. Kinematic and force data, as well as interfragmentary motion were recorded.

RESULTS

At 70°, CO failed at a mean load of 963 N (SD 104 N), the OO at 1512 N (SD 208 N) and the SO at 1484 N (SD 153 N), (P<0.001). At 20°, CO failed at a mean load of 707 N (SD 104 N) and OO at 1009 N (SD 85 N) (P=0.006). The highest load to failure was observed for the SO, which was 1277 N (SD 172 N). The load to failure of the SO was significantly higher than the CO as well as the OO.

CONCLUSION

Extra-articular osteotomies showed a significantly higher load to failure in comparison to traditional CO. At near full extension (20° of flexion), this biomechanical advantage was further enhanced by a step-cut modification of the extra-articular oblique osteotomy.

Splintage in the treatment of sagittal band incompetence and extensor tendon subluxation

This study assessed the success of splintage for traumatic and atraumatic sagittal band incompetence and its relationship to the duration of symptoms before treatment. A retrospective review of all patients with sagittal band incompetence treated with splintage was performed. All patients had extensor tendon subluxation on physical examination. Ninety-two patients were included: 68 traumatic and 24 atraumatic. Subluxation resolved with splintage in 77 patients. Traumatic tendon subluxation resolved in 95% of acute injuries, 100% of subacute injuries, and 67% of chronic injures. Atraumatic tendon subluxation resolved in 100% of patients with acute presentation, 67% of patients with subacute presentation, and 57% of patients with chronic presentation. Surgery was rarely required. Splintage proved very effective for acute sagittal band incompetence, regardless of causation, but decreased in efficiency with chronicity.

LEVEL OF EVIDENCE

Level 4.

Magnetic resonance imaging of the extensor mechanism

Anterior knee pain is associated with many different causes. The clinical diagnosis may be unclear when the patient initially presents for evaluation. Magnetic resonance (MR) imaging is a valuable modality with high diagnostic accuracy in the evaluation of extensor mechanism pathology, which commonly presents with anterior knee pain. The most common disorders include patellar fracture, patellofemoral tracking abnormalities, tendon trauma and degeneration. These injuries manifest with characteristic patterns on MR imaging. This article discusses normal anatomy, common injuries, and diagnostic pitfalls on MR imaging.

Prepatellar continuation rupture: Report of an unusual case

In anatomical studies the deepest soft tissue layer, related to the deep rectus femoris tendinous fibers, has been described as the "prepatellar quadriceps continuation". We present an unusual case of an isolated prepatellar continuation rupture, which to our knowledge is the first described case in the literature. Injuries to the extensor mechanism may include isolated rupture of the prepatellar continuation with intact quadriceps and patellar tendons. Diagnosis may be difficult with ultrasound scan and requires MRI scan for confirmation. Appropriate clinical assessment and regular physiotherapy lead to a full functional recovery.

Total knee arthroplasty in hemophiliacs: gains in range of motion realized beyond twelve months postoperatively

Background

Hemophiliacs have extrinsic tightness from quadriceps and flexion contractures. We sought to examine the effect of a focused physical therapy regimen geared to hemophilic total knee arthroplasty.

Methods

Twenty-four knees undergoing intensive hemophiliac-specific physical therapy after total knee arthroplasty, at an average age of 46 years, were followed to an average 50 months.

Results

For all patients, flexion contracture improved from -10.5 degrees preoperatively to -5.1 degrees at final follow-up (p = 0.02). Knees with preoperative flexion less than 90 degrees were compared to knees with preoperative flexion greater than 90 degrees. Patients with preoperative flexion less than 90 degrees experienced improved flexion (p = 0.02), along with improved arc range of motion (ROM) and decreased flexion contracture. For those patients with specific twelve-month and final follow-up data points, there was a significant gain in flexion between twelve months and final follow-up (p = 0.02).

Conclusions

Hemophiliacs with the poorest flexion benefited most from focused quadriceps stretching to a more functional length, with gains not usually seen in the osteoarthritic population. This data may challenge traditional views that ROM gains are not expected beyond 12-18 months.

Patellar tendon reconstruction using LARS ligament: surgical technique and case report

Neglected patella tendon ruptures require reconstruction using tendon grafts. The LARS ligament has been successfully used in cruciate and collateral knee ligament reconstruction. We present a technique using LARS ligament for the reconstruction of a chronic patella tendon rupture in a low-demand patient. The result after 1-year follow-up was deemed successful.

Complete avulsion of the extensor mechanism of a finger with simultaneous dislocation of the proximal interphalangeal joint

We report a rare case of open dislocation of the proximal interphalangeal (PIP) joint, associated with simultaneous avulsion of the central band and distal insertion of the extensor mechanism, rapture of the proximal volar plate, and rapture of the ulnar collateral ligament of the PIP joint.

Although isolated IP joint injuries are common, they rarely occur simultaneously in a single finger. Even more rarely are they accompanied by a complete avulsion of the extensor mechanism. Operative restoration of the injured structures is a necessity in order to achieve a good functional outcome.

An initial forceful flexion of the finger resulting to rapture of the extensor apparatus and then followed by finger hyperextension and PIP joint dislocation is our perception of the possible mechanism of this extremely rare injury.