Comparative study of various internal fixation methods for treating patellar fractures by three-dimensional photoelasticity

Objective: To compare the biomechanical basis of 3 different internal fixation methods: nitinol patellar concentrator (NT-PC), tension band and wire circle in treating patellar fractures. Methods: The epoxy resin three dimensional photoelasticity patellar models were made by precise moulding, and were fixated by nitinol patellar concentrator (NT-PC), tension band and wire circle respectively. The patellar models with frozen stress stripes were put into the polarized light field and the stress distributions were compared. As for the model fixated by NT-PC, by dividing layer, photographing and tracing, we used the iterative method to calculate the stress value of every internal node of the epoxy resin patellar model, and the character of stress was analyzed. Results: An overall stress field was yielded when the patellar model was fixated by NT-PC, and the stripes were more than that of tension band model and wire circle model, which have only few stress stripes in the fixated layers. Further analysis indicated that there were continuous fixated stresses in the facies articularis and distal pole of patella, and the character of stresses produced by NT-PC were mainly in longitudinal direction, then in transverse direction. The shearing stresses were small. Conclusion: The initiative and continuous memorial stress of NT-PC and its overall stress distribution character are the essence of NT-PC distinguished with tension band and wire circle in treating patellar fractures. The stress character produced by NT-PC is good for the stability of fracture site and prompts fracture healing.

Internal fixation and unicompartmental knee arthroplasty for an elderly patient with patellar fracture and anteromedial osteoarthritis:A case report

BACKGROUND Open reduction and internal fixation(ORIF)is the traditional surgical treatment for patellar fractures,and unicompartmental knee arthroplasty(UKA),especially Oxford UKA,has been increasingly used in patients with medial knee osteoarthritis(OA).However,the process of choosing treatment for patients with both patellar fractures and anteromedial knee OA remains unclear.We present the case of a patient with a patellar fracture and anteromedial OA.CASE SUMMARY We present the case of a 72-year-old woman with a history of bilateral medial compartment OA of the knees and a right Oxford UKA.She also experienced a recent left patellar fracture.ORIF and Oxford UKA were performed in a single stage.The patient showed excellent postoperative clinical results.CONCLUSION ORIF and Oxford UKA can be performed simultaneously for patients with patellar fracture and anteromedial OA on the same knee.

Clinical study of polydloxanone suture tension band fixation for treatment of patellar fractures

To explore biomechanic characteristics and clinical outcome of absorbable polydloxanone (PDS) treating patellar fractures.Methods The tensile strength test of PDS 0-0 or PDS 1-0 sutures were made in WDW305 electro-universal tester.A total of 60 cases were classified randomly and equally into two groups:treatment group (treated with the absorbable PDS tension hand) and Kirschner wire metals tension band control group (control group).Anatomy reduction was performed with towel clip fixation during operation.Treatment group was managed with diameter 1.5 mm Kirschner wires drilling two pores on the near or distal segment of patellar fracture end are penetrating through two strands of absorbable PDS 0-0 or PDS 1-0 sutures for a satisfactory fracture fixation.Control group was treated with Kirschner wires (2.0 mm in diameter) and steel wire (1.0 mm in diameter) of type “8” tension band fixation.Results Tensile strength testing showed that the biggest tensile of a strand PDS 0-0 sutures was 71.50 N and that of PDS 1-0 97.48 N,when the length was three times more than the initial.Two groups were followed up and the mean fracture healing time was two months,without broken wire or dislocation.Treatment group showed excellent clinical results in 21 cases,good in six and fair in three;while control group showed excellent clinical results in 19 cases,good in seven and fair in four,with no statistical difference compared with treatment group (χ2=0.32,P>0.05).Conclusion Absorbable PDS tension band has better characteristics of mechanics and creepage in treating patellar fractures.It can avoid defects of secondary operation and complications like needle-tail pain and sharped skin resulted from metal tension band fixation.Meanwhile,it is economic and worthy of further clinical application.16 refs,4 figs.

Comparison of a minimally invasive osteosynthesis technique with conventional open surgery for transverse patellar fractures

Parpose:The study aims to compare the efficacy and safety of a new minimally invasive osteosynthesis technique with those of conventional open surgery for transverse patellar fractures.Methods:It was a retrospective study.Adult patients with closed transverse patellar fracture were included,and with open comminuted patellar fracture were excluded.These patients were divided into minimally invasive osteosynthesis technique(MIOT)group and open reduction and internal fixation(ORIF)group.Surgical time,frequency of intraoperative fluoroscopy,visual analogue scale score,flexion,extension,Lysholm knee score,infection,malreduction,implant migration and implant irritation in two groups were recorded and compared.Statistical analysis was performed by the SPsS software package(version 19).A p<0.05 indicated statistical significance.Results:A total of 55 patients with transverse patellar fractures enrolled in this study,the minimally invasive technique was performed in 27 cases,and open reduction was performed in 28 cases.The surgical time in the ORIF group was shorter than that in the MIOT group(p=0.033).The visual analogue scale scores in the MIOT group were significantly lower than those in the ORIF group only in the first month after surgery(p=0.015).Flexion was restored faster in the MIOT group than that in the ORIF group at one month(p=0.001)and three months(p=0.015).Extension was recovered faster in the MIOT group than that in the ORIF group at one month(p=0.031)and three months(p=0.023).The recorded Lysholm knee scores in the MIOT group were always greater than those in the ORIF group.Complications,such as infection,malreduction,implant migration,and implant irritation,occurred more frequently in the ORIF group.Conclusion:Compared with the ORIF group,the MIOT group reduced postoperative pain and had less complications and better exercise rehabilitation.Although it requires a long operation time,MIOT may be a wise choice for transverse patellar fractures.

Biodegradable magnesium pins enhanced the healing of transverse patellar fracture in rabbits

Displaced fractures of patella often require open reduction surgery and internal fixation to restore the extensor continuity and articular congruity.Fracture fixation with biodegradable magnesium(Mg)pins enhanced fracture healing.We hypothesized that fixation with Mg pins and their degradation over time would enhance healing of patellar fracture radiologically,mechanically,and histologically.Transverse patellar fracture surgery was performed on thirty-two 18-weeks old female New Zealand White Rabbits.The fracture was fixed with a pin made of stainless steel or pure Mg,and a figure-of-eight stainless steel band wire.Samples were harvested at week 8 or 12,and assessed with microCT,tensile testing,microindentation,and histology.Microarchitectural analysis showed that Mg group showed 12%higher in the ratio of bone volume to tissue volume at week 8,and 38.4%higher of bone volume at week 12.Tensile testing showed that the failure load and stiffness of Mg group were 66.9%and 104%higher than the control group at week 8,respectively.At week 12,Mg group was 60.8%higher in ultimate strength than the control group.Microindentation showed that,compared to the Control group,Mg group showed 49.9%higher Vickers hardness and 31%higher elastic modulus at week 8 and 12,respectively.At week 12,the new bone of Mg group remodelled to laminar bone,but those of the control group remained woven bone-like.Fixation of transverse patellar fracture with Mg pins and its degradation enhanced new bone formation and mechanical properties of the repaired patella compared to the Control group.

Comparison of the clinical efficacy of different fixation systems for the treatment of transverse patellar fractures

Purpose:This study was designed to compare the clinical efficacy of"8"and"0"wire fixation systems combined with double-head cannulated compression screws or Kirschner wires for the treatment of transverse patellar fractures.Methods:From September 2011 to September 2018,patients with closed transverse patellar fractures treated with a double-head compression screw or Kirschner wire were included and analyzed retrospectively.Patients with patellar fractures combined with distal femoral fractures,tibial plateau fracture or preoperative lower limb dysfunction were excluded.The patients treated with the"8"tension band wire fixation system and Kirschner wire were taken as Group A;those treated with the"0"fixation system and Kirschner wire were taken as Group B;those treated with the"8"fixation system and double-head cannulated compression screw were taken as group C;and those treated with the"0"fixation system and double-head cannulated compression screw were taken as group D.Six weeks and one year after the operation and every month from the third month after the operation until the fractures healed,an X-ray examination was performed to identify fracture healing.The time of fracture healing and postoperative complications of the four groups were compared.One year after the operation,knee function was evaluated by Bostman’s score.Results:During the study period,168 patients with patellar fractures were treated by operations,and 88 patients were excluded because the fracture type did not meet the requirements or because there were combined fractures of the distal femur or tibial plateau.As a result,80 patients were included in this study,20 in each group.All the patients were followed up for an average period of 12.2 months.Compared with Group A,patients in Group D presented less postoperative discomfort in the prepatellar region,quicker fracture healing,less fixation failure and better postoperative knee function scores(all p<0.05).The incidence of internal fixation failure in Group(B+D)was lower than that in Group(A+C)(p>0.05).Conclusion:The"0"wire fixation system combined with a double-head cannulated compression screw seems to be more beneficial than the other three fixation systems for the treatment of transverse patellar fractures.

Early patellar tendon rupture after total knee arthroplasty: A direct repair method

BACKGROUND Patellar tendon rupture after total knee arthroplasty(TKA)is a catastrophic complication.Although the occurrence of this injury is rare,it can lead to significant dysfunction for the patient and is very tricky to deal with.There has been no standard treatment for early patella tendon rupture after TKA,and long-term follow-up data are lacking.AIM To introduce a direct repair method for early patella tendon rupture following TKA and determine the clinical outcomes and complications of this method.METHODS During the period of 2008 to 2021,3265 consecutive TKAs were retrospectively reviewed.Twelve patients developed early patellar tendon rupture postoperatively and were treated by a direct repair method.Mean follow-up was 5.7 years.Demographic,operative,and clinical data were collected.The clinical outcomes were assessed using the Western Ontario and McMaster Universities(WOMAC)score,the Hospital for Special Surgery(HSS)score,knee range of motion,extensor lag,and surgical complications.Descriptive statistics and paired t test were employed to analyze the data.RESULTS For all 12 patients who underwent direct repair for early patellar tendon rupture,3 patients failed:One(8.3%)for infection and two(17.6%)for re-fracture.The two patients with re-fracture both underwent reoperation to reconstruct the extensor mechanism and the patient with infection underwent revision surgery.The range of motion was 109.2°±10.6°preoperatively to 87.9°±11°postoperatively,mean extensor lag was 21°at follow-up,and mean WOMAC and HSS scores were 65.8±30.9 and 60.3±21.7 points,respectively.CONCLUSION This direct repair method of early patellar tendon rupture is not an ideal therapy.It is actually ineffective for the recovery of knee joint function in patients,and is still associated with severe knee extension lag and high complication rates.Compared with the outcomes of other repair methods mentioned in the literature,this direct repair method shows poor clinical outcomes.

Autogenous iliotibial band enhancement combined with tendon lengthening plasty to treat patella baja:A case report

BACKGROUND Patella baja is a severe complication after knee injury or surgery,resulting in pain and impaired movement.This disorder is also a substantial challenge for orthopaedic surgeons.Currently,no consensus exists regarding the gold standard management of patella baja.If not appropriately treated,significant dysfunction of the knee joint will occur.CASE SUMMARY A 46-year-old man with a left patellar fracture was treated with tension band fixation at a local hospital.He had undergone a second operation at the same hospital because of limited knee flexion 6 mo after surgery.Unfortunately,the patellar tendon was ruptured.The patellar tendon was subsequently repaired using an ipsilateral semitendinosus tendon.Two years later,the patient presented to our department with knee pain and loss of range of motion.Autogenous iliotibial band(ITB)enhancement combined with sagittal tendon lengthening plasty was used to improve the symptoms of the knee joint.The patient was followed up for 2 years.The knee joint function of the patient returned to the normal level.CONCLUSION We successfully treated patella baja using autogenous ITB enhancement combined with sagittal tendon lengthening plasty.

Closed patella fracture combined with cruciate ligament injury： a case control study

Background Patellar fracture and cruciate ligament injury are a common consequence of traumatic knee injury. Patellar fracture combined with cruciate ligament injury is rarely reported, although the mechanisms of two things are similar. This study aimed to evaluate the incidence of closed patella fracture combined with cruciate ligament injury.