Chondral and osteochondral fractures after luxation of the patella and their treatment

Medial patellofemoral ligament reconstruction with simultaneous osteochondral fracture fixation is an effective treatment for adolescent patellar dislocation with osteochondral fractures

BACKGROUND

Osteochondral fractures can occur during patellar dislocation and often require treatment. The purpose of this study is to determine the incidence of recurrent instability and second surgery following osteochondral fracture fixation with concomitant medial patellofemoral ligament reconstruction.

METHODS

A retrospective review of a cohort of 365 medial patellofemoral ligament reconstructions by a single surgeon from 2008 to 2019 was performed to identify patients who underwent simultaneous osteochondral fracture fixation with bioabsorbable nails. Demographic data, surgical details, clinical follow-up, and subsequent procedures were collected.

RESULTS

Forty medial patellofemoral ligament reconstructions with osteochondral fracture fixation were performed by a single surgeon from 2008 to 2019. The average age at surgery was 14.6 years (range 10.7-19.6 years). The average length of follow-up was 2.6 years (range 0.7-7.0 years). Eleven (28%) patients required a second surgery on the ipsilateral knee. One patient had recurrent instability and required revision medial patellofemoral ligament reconstruction and osteochondral allograft. The other 10 patients underwent a second surgery to address cartilage damage or debridement of nails. Of the four patients who required nail debridement, the average number of nails initially placed was 7 ± 1.7. This was significantly more than the patients who did not require second surgery related to nail debridement (4.1 ± 1.6, p < .05).

CONCLUSION

28% of patients required a second procedure, most of which involved debridement of unhealed portions of the osteochondral fracture. At 2.6-year follow-up, only 2% of patients had a failure of their osteochondral fracture fixation requiring a cartilage restoration procedure. Osteochondral fracture fixation in adolescents with patellofemoral instability can be effectively treated with fixation and simultaneous medial patellofemoral ligament reconstruction.

LEVEL OF EVIDENCE

level IV.

One-Stage Osteochondral Fracture Repair Technique With Knotless Anchors and Interconnected Crossing Suture Sliding Loops for the Knee

Osteochondral fractures of the knee represent a challenging entity to manage since there are many different surgical techniques for cartilage repair or other salvage procedures. In terms of cartilage repair, several hardware devices can be used, and many of them could imply a second-stage surgery for hardware removal. The purpose of this article is to describe in detail a one-stage osteochondral fracture repair technique with knotless anchors and interconnected crossing suture sliding loops for the knee. This technique is a one-stage open or arthroscopic procedure with an unlimited number of loops configurations with no particular need for a second surgery for hardware removal, no knot damage, and without the use of bone tunnels. It can be used in different cartilage anatomic locations, such as femoral condyles, trochlea, patella, or other joints.

Clinical Results and MRI Evaluation of Patellar Osteochondral Fracture Fixation following Patellar Dislocation

Aim

The aim of the study was to analyze the clinical results and MRI scans after transpatellar osteochondral fracture fixation following patellar dislocation.

Methods

Our study group comprised 17 patients with patellar dislocation followed by osteochondral fracture of the articular surface of the patella. All patients underwent surgery where the fractured osteochondral fragments of the patella were attached using the transpatellar suture technique. The mean age at the time of surgery was 14.1 years, and the mean follow-up period was 7.5 years.

Results

The results of the patellar compression test and the apprehension test were negative in all patients. The mean Lysholm and Kujala scores were 89.2 and 89.6, respectively. The MRI scan revealed healing of the fixed fragment and restoration of the articular surface in all patients. In 16 cases, subchondral bone of the fixed fragment area was described as irregular: its articular cartilage was narrowed and not homogenous. Progressive degenerative changes were observed in the patellofemoral joint at follow-up in three patients.

Conclusions

By fixing osteochondral fragments, the patellar articular surface can be restored. The MRI scans show that the cartilage in the reconstructed surface is narrowed after a mean 7.5-year follow-up.

Biomechanical evaluation of novel ultrasound-activated bioresorbable pins for the treatment of osteochondral fractures compared to established methods

BACKGROUND

Osteochondral injuries often lead to osteoarthritis of the affected joint. All established systems for refixation of osteochondral defects show certain disadvantages. To address the problem of reduced stability in resorbable implants, ultrasound-activated pins were developed. By ultrasound-activated melting of the tip of these implants, a more secure anchoring is assumed.

MATERIALS AND METHODS

The aim of the study was to investigate if ultrasound-activated pins can provide secure fixation of osteochondral fragments compared to screws and conventional resorbable pins. In a biomechanical laboratory setting, osteochondral fragments of the medial femoral condyle of sheep were refixated with ultrasound-activated pins [US fused poly(L-lactide-co-D,L-lactide) (PLDLLA) pins], polydioxanone (PDA) pins and conventional titanium screws. Anchoring forces of the different fixation methods were examined, registered and compared concerning shear force and tensile force.

RESULTS

Concerning the pull out test, the US fused PLDLLA pins and titanium screws (~122 N and ~203 N) showed comparable good results, while the PDA pins showed significantly lower anchoring forces (~18 N). Examination of shear forces showed a significantly higher anchoring of the screws (~248 N) than the US fused PLDLLA pins (~218 N). Nevertheless, the US fused PLDLLA pins could significantly outperform the PDA pins (~68 N) concerning shear forces.

CONCLUSION

The US fused PLDLLA pins demonstrated a comparable anchorage to the fixation with screws, but were free from the disadvantages of metal implants, i.e. the need for implant removal. The PDA pin application showed inferior biomechanical properties.

Current concepts review: Fractures of the patella

Fractures of the patella account for about 1% of all skeletal injuries and can lead to profound impairment due to its crucial function in the extensor mechanism of the knee. Diagnosis is based on the injury mechanism, physical examination and radiological findings. While the clinical diagnosis is often distinct, there are numerous treatment options available. The type of treatment as well as the optimum timing of surgical intervention depends on the underlying fracture type, the associated soft tissue damage, patient factors (i.e. age, bone quality, activity level and compliance) and the stability of the extensor mechanism. Regardless of the treatment method an early rehabilitation is recommended in order to avoid contractures of the knee joint capsule and cartilage degeneration.

For non-displaced and dislocated non-comminuted transverse patellar fractures (2-part) modified anterior tension band wiring is the treatment of choice and can be combined – due to its biomechanical superiority – with cannulated screw fixation. In severe comminuted fractures, open reduction and fixation with small fragment screws or new angular stable plates for anatomic restoration of the retropatellar surface and extension mechanism results in best outcome. Additional circular cerclage wiring using either typical metal cerclage wires or resorbable PDS/non-resorbable FiberWires increases fixation stability and decreases risk for re-dislocation. Distal avulsion fractures should be fixed with small fragment screws and should be protected by a transtibial McLaughlin cerclage. Partial or complete patellectomy should be regarded only as a very rare salvage operation due to its severe functional impairment.

Refixation of Osteochondral Fractures by an Ultrasound-Activated Pin System - An Ovine In Vivo Examination Using CT and Scanning Electron Microscope

Background:

Osteochondral injuries, if not treated appropriately, often lead to severe osteoarthritis of the affected joint. Without refixation of the osteochondral fragment, human cartilage only repairs these defects imperfectly. All existing refixation systems for chondral defects have disadvantages, for instance bad MRI quality in the postoperative follow-up or low anchoring forces. To address the problem of reduced stability in resorbable implants, ultrasound-activated pins were developed. By ultrasound-activated melting of the tip of these implants a higher anchoring is assumed. Aim of the study was to investigate, if ultrasound-activated pins can provide a secure refixation of osteochondral fractures comparing to conventional screw and conventional, resorbable pin osteosynthesis. CT scans and scanning electron microscopy should proovegood refixation results with no further tissue damage by the melting of the ultrasound-activated pins in comparison to conventional osteosynthesis.

Methods:

Femoral osteochondral fragments in sheep were refixated with ultrasound-activated pins (SonicPin™), Ethipins^® and screws (Asnis™). The quality of the refixated fragments was examined after three month of full weight bearing by CT scans and scanning electron microscopy of the cartilage surface.

Results:

The CT examination found almost no statistically significant difference in the quality of refixation between the three different implants used. Concerning the CT morphology, ultrasound-activated pins demonstrated at least the same quality in refixation of osteochondral fragments as conventional resorbable pins or screws. The scanning electron microscopy showed no major surface damage by the three implants, especially any postulated cartilage damage induced by the heat of the ultrasound-activated pin. The screws protruded above the cartilage surface, which may affect the opposingtibial surface.

Conclusion:

Using CT scans and scanning electron microscopy, the SonicPin™, the Ethipin^® and screws were at least equivalent in refixation quality of osteochondral fragments.

Adolescent patellar osteochondral fracture following patellar dislocation

PURPOSE

Patellar dislocations in adolescents may cause osteochondral fractures of the patella. The aim of this study was to review the outcomes of adolescent patients who underwent surgical intervention for patellar osteochondral fracture following patellar dislocation.

METHODS

Nine patients who underwent surgery for osteochondral fracture of the patella following dislocation were identified retrospectively. Following arthroscopic examination, if the fragment was large enough to support fixation, headless screws or bioabsorbable pins were used. Otherwise, the loose body was excised, and the donor site was managed with a microfracture. Postoperatively, patients were assessed using the International Knee Documentation Committee (IKDC) and Knee injury and Osteoarthritis Outcome Score (KOOS) outcome measures.

RESULTS

The average age of the patients was 14.6 with average follow-up 30.2 months. Four of the nine patients underwent fixation, while five patients underwent removal of loose body with microfracture. The average defect size in the nonfixation group was 1.2 cm(2) compared with 3.2 cm(2) in the fixation group. The IKDC scores for fixation and nonfixation groups were 63.9 (SD = 18) and 76.1 (SD = 11.7), respectively. The KOOS subscale scores for symptoms, function in sports and recreation, and knee-related quality of life were higher for the nonfixation group when compared to the fixation group.

CONCLUSIONS

This is the first known series examining surgical outcomes of osteochondral fractures of the patella following patellar dislocations in the adolescent population. While patients without fixation were less symptomatic in this series, this may be attributable to more severe injuries in patients undergoing fracture fixation.

LEVEL OF EVIDENCE

Retrospective case series, Level IV.

Refixation of osteochondral fractures by ultrasound-activated, resorbable pins: An ovine in vivo study

Objectives

Osteochondral injuries, if not treated adequately, often lead to severe osteoarthritis. Possible treatment options include refixation of the fragment or replacement therapies such as Pridie drilling, microfracture or osteochondral grafts, all of which have certain disadvantages. Only refixation of the fragment can produce a smooth and resilient joint surface. The aim of this study was the evaluation of an ultrasound-activated bioresorbable pin for the refixation of osteochondral fragments under physiological conditions.

Methods

In 16 Merino sheep, specific osteochondral fragments of the medial femoral condyle were produced and refixed with one of conventional bioresorbable pins, titanium screws or ultrasound-activated pins. Macro- and microscopic scoring was undertaken after three months.

Results

The healing ratio with ultrasound-activated pins was higher than with conventional pins. No negative heat effect on cartilage has been shown.

Conclusion

As the material is bioresorbable, no further surgery is required to remove the implant. MRI imaging is not compromised, as it is with implanted screws. The use of bioresorbable pins using ultrasound is a promising technology for the refixation of osteochondral fractures.

[Classification and treatment of patella fractures]

Patella fractures are rare and account for approximately 1% of all fractures. They are classified regarding their localization (proximal, distal) and appearance. The aim of any treatment is reconstruction of the extensor mechanism and joint surface. If dislocation and cartilage steps are less than 2 mm, conservative treatment may be indicated. Operative treatment is only necessary if a dislocation is more than 2 mm or when the extensor mechanism is unstable. Depending on the shape of the fracture, tension band wiring, interfragmentary screw fixation and combinations are the main techniques. Because patellectomy has functionally the worst result it should be avoided. Sleeve fractures (children) need exact reconstruction of the joint surface. In elderly patients conservative treatment or surgical patella-enclosing wiring techniques for stabilization are the best options due to low bone quality.

[Fractures of the patella]

Fractures of the patella account for approximately 0.5% to 1.5% of all skeletal injuries. The diagnosis is made by means of the mechanism of injury, physical and radiological findings. The kind of treatment of patella fractures depends on the type of fracture, the size of the fragments, the integrity of the extensor mechanism and the congruity of the articular surface. Independent of the kind of treatment an early rehabilitation is recommended. Modified tension band wiring is the most commonly used surgical treatment for patella fractures and can be used for almost every type of fracture. Due the superior stability in biomechanical studies two parallel cannulated lag screws combined with a tension band wiring are the treatment of choice for horizontally displaced two-part fractures. In comminuted fractures a partial or total patellectomy may be necessary. However, since the loss of quadriceps muscle power and the poor outcome total patellectomy should be considered as a salvage procedure.

[Imaging examinations of the patellofemoral joint]

Lesions in the patellofemoral region can be caused by trauma, chronic overloading, and especially regarding cartilage alterations by normal aging or pathologic processes. Very commonly these lesions lead to early arthrosis. An accurate clinical evaluation in all these patients is recommended. The combination of clinical information and radiological examinations should end up with an exact diagnosis.As part of the radiological evaluation of complaints of the patellofemoral region MR imaging is of special value since this method allows direct visualization of all intra- and extra-articular structures and their alterations, ultimately aiding in planning sufficient therapy. Moreover, is it possible to exclude pathology by MR imaging, which helps to prevent useless treatment and surgical procedures.

Patella Dislocation

In brief Whenever a patient has a patella dislocation, osteochondral fractures should be considered. A case study involving a 17-year-old swimmer whose knee was injured playing baseball details a patella dislocation that was accompanied by a defect of the medial patellar facet and a lateral impaction lesion of the lateral femoral gutter-both producing loose bodies. Careful physical examination and a radiographic series that includes anteroposterior, lateral, notch, and sunrise patella views assist in making an accurate diagnosis and guide the clinician to the appropriate treatment. Treatment involves a knee stabilizer followed by aggressive quadriceps strengthening. Loose bodies require arthroscopic surgery.

Autoarthroplasty of knee cartilage defects by osteoperiosteal grafts

Five fresh osteochondral fractures of the knee, which could not be fixed because of extensive fragmentation, were treated by excision of the fragments and reconstruction of the joint surface defect by an autogenous osteoperiosteal graft. The procedure was also used for joint surface reconstruction in sclerotic osteochondritis of the femoral condyle (nine knees) and grave patellofemoral chondromalacia (three knees). Plaster cast immobilization for 3 weeks was used in the two early cases. In all other cases, we employed a passive motion apparatus for 2 days postoperatively, followed by active mobilization in a knee brace with extension-flexion 30 to 90 degrees (femoral condyle reconstruction) or 0 to 45 degrees (patellar reconstruction). Gradual free movements were started 3 weeks postoperatively. The results after 1.5 to 6.5 years were satisfactory in all but one case. One arthroscopic removal of the loose graft was performed, as were two arthroscopic graft margin shavings. Three other reoperations were unrelated to the osteoperiosteal reconstruction. It appears that periosteal reconstruction should be considered in local osteochondral lesions, where excision of the injured cartilage is mandatory. The results were best in fresh trauma cases and younger people.

Autogenous osteoperiosteal grafts in the reconstruction of full-thickness joint surface defects

Free, autogenous periosteal grafts from the medial metaphysis of the proximal tibia have been used to reconstruct full thickness cartilage defects of the articular surfaces of the knee joint. If there was a bone defect, it was initially filled with cancellous bone graft. The method is illustrated by six patients, three with acute traumatic patellar defects and three with local sclerotic osteochondritis of the medial femoral condyle. The latter had loose fragments unsuitable for fixation and single excision would have left a large and deep defect. The grafts have given satisfactory results, 14 to 59 months after the procedures. Clinical grading of the defects has been monitored by radiographs with arthroscopy of two knees and CT scan of one knee.

Chondral and osteochondral fractures of the knee joint--treatment and results

This paper reports on experience in various methods of reconstructive and palliative surgery in 50 patients and discusses the problems of establishing a diagnosis. The clinical symptoms are decisive; the conclusive indication for surgery is the detection of a hemarthrosis. Persistent cartilaginous defects in chondral or osteochrondral fractures will lead to the development of secondary arthrosis of the knee joint. Therefore, we emphasize immediate surgical revision of the injured joint. The results obtained in this way are good, especially in younger patients.