Anterior cervical interbody fusion with a titanium box cage: early radiological assessment of fusion and subsidence

BACKGROUND CONTEXT

The use of stand-alone cervical interbody cages in anterior cervical discectomy with fusion (ACDF) has become popular, but high subsidence rates have been reported in the literature.

PURPOSE

The authors present short-term radiological results of a titanium box cage with regard to fusion and subsidence. Reliable fusion and lack of subsidence may influence long-term clinical results. Early radiological data are necessary before implementation of this device on a larger scale can be accepted.

STUDY DESIGN/SETTING

Retrospective radiological quality assessment study.

PATIENT SAMPLE

ACDF using the titanium cage was performed in 71 consecutive patients at 106 levels. Diagnoses included cervical disc disease (57) and cervical spinal stenosis (14) after failed conservative treatment.

OUTCOME MEASURES

Subsidence and kyphosis were assessed on lateral cervical radiographs made directly postoperative and at 3- and 6-month follow-up. At 6-month follow-up, lateral flexion-extension radiographs were made to assess fusion.

METHODS

Subsidence of the cage was defined as a decrease in total vertical height of the two fused vertebral bodies as measured on the lateral cervical radiographs made 3 and 6 months postoperatively compared with the directly postoperative radiographs. Segmental kyphosis was measured as the angle between the posterior borders of the two vertebral bodies on the lateral radiograph.

RESULTS

No patients were lost to follow-up. Fusion was achieved after 6 months in all patients. At 3 and 6 months postoperative the same 10 cages (each in a different patient) had subsided. The C6-C7 level was significantly more frequently involved compared with all other levels. A segmental kyphotic alignment was observed in five patients at the C6-C7 level and in one patient at the C4-C5 level.

CONCLUSIONS

For patients with cervical disc disease, the high subsidence tendency of the cage into the end plate of predominantly C7 is a disturbing phenomenon found in this study. A modified cage design that improves and extends contact with the inferior surface could be expected to reduce subsidence into C7.

Isolated patellofemoral osteoarthritis

BACKGROUND AND PURPOSE

The optimal treatment for isolated patellofemoral osteoarthritis is unclear at present. We systematically reviewed the highest level of available evidence on the nonoperative and operative treatment of isolated patellofemoral osteoarthritis to develop an evidenced-based discussion of treatment options.

METHODS

A systematic computerized database search (Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, MEDLINE (PubMed), and EMBASE) was performed in March 2009. The quality of the studies was assessed independently by two authors using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

We extracted data from 44 articles. The best available evidence for treatment of isolated patellofemoral osteoarthritis is sparse and of generally low methodological quality. Nonoperative treatment using physiotherapy (GRADE: high quality, weak recommendation for use), taping (GRADE: moderate quality, weak recommendation for use), or injection therapy (GRADE: very low quality, weak recommendation for use) may result in short-term relief. Joint-preserving surgical treatment may result in insufficient, unpredictable, or only short-term improvement (GRADE: low quality, weak recommendation against use). Total knee replacement with patellar resurfacing results in predictable and good, durable results (GRADE: low quality, weak recommendation for use). Outcome after patellofemoral arthroplasty in selected patients is good to excellent (GRADE: low quality, weak recommendation for use).

INTERPRETATION

Methodologically good quality comparative studies, preferably using a patient-relevant outcome instrument, are needed to establish the optimal treatment strategy for patients with isolated patellofemoral osteoarthritis.

Conversion of patellofemoral arthroplasty to total knee arthroplasty: A matched case-control study of 13 patients

BACKGROUND AND PURPOSE

The long-term outcome of patellofemoral arthroplasty is related to progression of femorotibial osteoarthritis with need for conversion to total knee arthroplasty. We investigated whether prior patellofemoral arthroplasty compromises the results of total knee arthroplasty.

METHODS

13 patients who had had 14 Richards type II patellofemoral arthroplasties converted to total knee arthroplasty because of femorotibial osteoarthritis, were individually matched to a control group of 13 patients with 14 primary total knee arthroplasties. The mean follow-up times for the patients and the control group were 5.7 (2-13) years and 5.2 (2-13) years, respectively. Clinical outcome was assessed using Knee Society score (KSS), WOMAC score, range of motion, and complications.

RESULTS

KSS and WOMAC scores were similar in the two groups (KSS in patient and control groups: 82 and 86 (p = 0.6); KSS function: 76 and 88 (p = 0.5); WOMAC score: 33 and 21 (p = 0.1)). Within 6 months after conversion, 3 knees had to be manipulated under anesthesia for limited motion. No patients in the control group required manipulation under anesthesia.

INTERPRETATION

Patellofemoral arthroplasty appears not to have a negative effect on the outcome of later total knee arthroplasty.

A dutch survey on circumpatellar electrocautery in total knee arthroplasty

Introduction:

Anterior knee pain following total knee arthroplasty is estimated to occur in 4-49% of patients. Some orthopedic surgeons use circumpatellar electrocautery (diathermy) to reduce the prevalence of postsurgical anterior knee pain; however, the extent of its use is unknown.

Materials and Methodology:

In April 2009, a postal questionnaire was sent to all 98 departments of orthopedic surgery in The Netherlands. The questions focused on the frequency of total knee arthroplasties, patellar resurfacing, and the use of circumpatellar electrocautery.

Results:

The response rate was 92%. A total of 18,876 TKAs, 2,096 unicompartmental knee arthroplasties, and 215 patellofemoral arthroplasties are performed yearly in The Netherlands by the responding orthopedic surgeons. Of the orthopedic surgeons performing TKA, 13% always use patellar resurfacing in total knee arthroplasty for osteoarthritis, 49% use selective patellar resurfacing, and 38% never use it. Fifty-six percent of orthopedic surgeons use circumpatellar electrocautery when not resurfacing the patella, and 32% use electrocautery when resurfacing the patella.

Conclusion:

There is no consensus among Dutch orthopedic surgeons on the use of patellar resurfacing or circumpatellar electrocautery in total knee replacement performed for osteoarthritis. A prospective clinical trial is currently underway to fully evaluate the effect of circumpatellar electrocautery on the prevalence of anterior knee pain following total knee arthroplasty.

Reliability, validity, and responsiveness of the Western Ontario and McMaster Universities Osteoarthritis Index for elderly patients with a femoral neck fracture

BACKGROUND

The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) has been extensively evaluated in groups of patients with osteoarthritis, yet not in patients with a femoral neck fracture. This study aimed to determine the reliability, construct validity, and responsiveness of the WOMAC compared with the Short Form-12 (SF-12) and the EuroQol 5D (EQ-5D) questionnaires for the assessment of elderly patients with a femoral neck fracture.

METHODS

Reliability was tested by assessing the Cronbach alpha. Construct validity was determined with the Pearson correlation coefficient. Change scores were calculated from ten weeks to twelve months of follow-up. Standardized response means and floor and ceiling effects were determined. Analyses were performed to compare the results for patients less than eighty years old with those for patients eighty years of age or older.

RESULTS

The mean WOMAC total score was 89 points before the fracture in the younger patients and increased from 70 points at ten weeks to 81 points at two years postoperatively. In the older age group, these scores were 86, 75, and 78 points. The mean WOMAC pain scores before the fracture and at ten weeks and two years postoperatively were 92, 76, and 87 points, respectively, in the younger age group and 92, 84, and 93 points in the older age group. Function scores were 89, 68, and 79 points for the younger age group and 84, 71, and 73 points for the older age group. The Cronbach alpha for pain, stiffness, function, and the total scale ranged from 0.83 to 0.98 for the younger age group and from 0.79 to 0.97 for the older age group. Construct validity was good, with 82% and 79% of predefined hypotheses confirmed in the younger and older age groups, respectively. Responsiveness was moderate. No floor effects were found. Moderate to large ceiling effects were found for pain and stiffness scales at ten weeks and twelve months in younger patients (18% to 36%) and in the older age group (38% to 53%).

CONCLUSIONS

The WOMAC showed good reliability, construct validity, and responsiveness in both age groups of elderly patients with a femoral neck fracture who had been physically and mentally fit before the fracture. The instrument is suitable for use in future clinical studies in these populations.

CLINICAL RELEVANCE

The results are based on two clinical trials. The questionnaires used concern pure, clinically relevant issues (ability to walk, climb stairs, etc.). Moreover, the results can be used for future research comparing clinical outcomes (or treatments) for populations with a femoral neck fracture.

Patient Satisfaction and Functional Outcomes Following Secondary Patellar Resurfacing

When secondary patellar resurfacing is performed, a uniformly and widely used scoring system that is validated for anterior knee pain caused by a retropatellar degeneration will give more insight into the results of this procedure. The cause of anterior knee pain following total knee arthroplasty (TKA) is not always related to the patella itself. Other causes have been identified, such as an insufficient posterior cruciate ligament in the case of a posterior cruciate-retaining TKA or an internally rotated femoral and/or tibial component. Treatment of anterior knee pain following primary TKA with secondary patellar resurfacing is a controversial procedure with uncertain outcomes. The purpose of this study is to systematically review the available peer-reviewed literature on patient satisfaction and functional outcomes of secondary resurfacing. The authors performed a systematic computerized database search of the Cochrane Database of Systematic Reviews, MEDLINE, and EMBASE in October 2014. The quality of the included studies was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach. A total of 15 articles met the inclusion criteria. In total, 148 (64%) of 232 patients were satisfied with the outcomes of secondary patellar resurfacing. A statistically significant improvement in knee scores was noted in all 9 studies that reported functional outcomes, although no clinically significant improvement in knee scores was observed. Reported complications include infections and impaired wound healing, patellar instability, and patellar fracture. Because the available evidence is of generally low quality, the results of this systematic review only support a weak recommendation for secondary patellar resurfacing if patient satisfaction and clinically important improvement of functional outcomes are the desired endpoints. [Orthopedics.2016; 39(5):e850-e856.].

Differences in the stress distribution in the distal femur between patellofemoral joint replacement and total knee replacement: a finite element study

Background

Patellofemoral joint replacement is a successful treatment option for isolated patellofemoral osteoarthritis. However, results of later conversion to total knee replacement may be compromised by periprosthetic bone loss. Previous clinical studies have demonstrated a decrease in distal femoral bone mineral density after patellofemoral joint replacement. It is unclear whether this is due to periprosthetic stress shielding. The main objective of the current study was to evaluate the stress shielding effect of prosthetic replacement with 2 different patellofemoral prosthetic designs and with a total knee prosthesis.

Methods

We developed a finite element model of an intact patellofemoral joint, and finite element models of patellofemoral joint replacement with a Journey PFJ prosthesis, a Richards II prosthesis, and a Genesis II total knee prosthesis. For each of these 4 finite element models, the average Von Mises stress in 2 clinically relevant regions of interest were evaluated during a simulated squatting movement until 120 degrees of flexion.

Results

During deep knee flexion, in the anterior region of interest, the average Von Mises stress with the Journey PFJ design was comparable to the physiological knee, while reduced by almost 25% for both the Richards II design and the Genesis II total knee joint replacement design. The average Von Mises stress in the supracondylar region of interest was similar for both patellofemoral prosthetic designs and the physiological model, with slightly lower stress for the Genesis II design.

Conclusions

Patellofemoral joint replacement results in periprosthetic stress-shielding, although to a smaller degree than in total knee replacement. Specific patellofemoral prosthetic design properties may result in differences in femoral stress shielding.

Secondary patellar resurfacing following total knee arthroplasty : A cohort study in fifty eight knees with a mean follow-up of thirty one months

PURPOSE

If anterior knee pain (AKP) emerges or persists following total knee arthroplasty (TKA), secondary patellar resurfacing (SPR) may offer relief of AKP. The purpose of our study was to evaluate the mid-term clinical outcomes after secondary patellar resurfacing for persistent AKP. Secondary objectives were to correlate surgical outcomes with clinical and radiological parameters including 99 m-technetium bone scintigraphy.

METHODS

In this study, 57 patients (58 knees, 51 women and 6 men) with a mean age of 70 years at the time of SPR were included. Patients were asked about their satisfaction regarding the outcome of the procedure. Patellar position was assessed by axial radiographs, and we reassessed the preoperatively performed bone scintigraphy.

RESULTS

After a median follow-up of 31 (6-76) months, 42 patients (43 knees) were satisfied and 15 were dissatisfied regarding the outcome of the procedure. Dissatisfied patients had more often a shorter time interval between TKA and SPR, patellar tilt on axial radiographs, and a 'hot' bone scan.

CONCLUSION

In patients with persistent AKP following TKR, secondary resurfacing leads to patient satisfaction in a relatively large number of patients. Better results were seen in patients without tilting of the patella. The added value of a bone scan as an indicator to perform SPR is not clarified in the present study.

Dissociation of mobile-bearing patellar component in low contact stress patellofemoral arthroplasty, its mechanism and management: two case reports

Introduction

Isolated patellofemoral osteoarthritis can be treated with patellofemoral arthroplasty.

Case presentation

We present two cases of isolated patellofemoral osteoarthritis treated with Low Contact Stress patellofemoral arthroplasty; in both cases the polyethylene mobile-bearing of the patellar component dissociated from the metal backing. One patient had a revision to a Richards patellofemoral prosthesis, and in the second patient the arthroplasty was converted to a total knee prosthesis because of clinically important femorotibial osteoarthritis.

Conclusion

The possible failure mechanisms are described. We suggest avoiding the use of a metal-backed mobile-bearing patellar component due to the risk of dissociation.

Distal femoral bone mineral density decreases following patellofemoral arthroplasty: 1-year follow-up study of 14 patients

Background

The bone mineral density (BMD) of the distal femur decreases by 16-36% within one year after total knee arthroplasty (TKA) because of the femoral component's stress-shielding effect. The aim of this prospective study was to determine the quantitative change from the baseline BMD in the distal femur 1 year after patellofemoral arthroplasty using dual-energy X-ray absorptiometry (DXA).

Methods

Between December 2007 and December 2008, 14 patients had patellofemoral arthroplasty for isolated patellofemoral osteoarthritis. Distal femoral BMD was assessed using DXA in 2 regions of interest (ROI) on the lateral view 2 weeks before and 12 months after patellofemoral arthroplasty. The contra-lateral knee was used as a control, with BMD measurements performed in identical ROIs.

Results

The mean change from baseline BMD in the operated knees after 1 year was -0.169 g/cm² (95% CI: -0.293 to -0.046 g/cm²) behind the anterior flange (-15%), and -0.076 g/cm² (95% CI: -0.177 to 0.024 g/cm²) in the supracondylar area 1 cm above the prosthesis (-8%) (p = 0.01 and p = 0.13, respectively). The mean change from baseline BMD in the non-operated knees after 1 year was 0.016 g/cm² (95% CI: -0.152 to 0.185 g/cm²) behind the anterior flange (2%), and 0.023 g/cm² (95% CI: -0.135 to 0.180 g/cm²) in the supracondylar area 1 cm above the prosthesis (2%) (p = 0.83, and p = 0.76, respectively).

Conclusions

Our findings suggest that patellofemoral arthroplasty results in a statistically significant decrease in BMD behind the anterior flange.

Femoral component rotation in patellofemoral joint replacement: a study protocol for a prospective observational study

Patellofemoral joint replacement is a successful treatment option for isolated patellofemoral osteoarthritis. The short and mid-term outcomes are related to malposition and unexplained pain. Whether external rotation of the femoral component in isolated patellofemoral joint replacement is required is unclear. The primary aim of this study is to determine the CT-measured femoral component rotation of patellofemoral joint replacement relative to the transepicondylar axis. The secondary aim is to correlate the CT-measured femoral component rotation with the clinical outcomes at 1-year follow-up as assessed with the KOOS questionnaire.

We designed a prospective observational study with medical research ethics committee and institutional review board approval. A total of 40 patients who will be treated with patellofemoral joint replacement for isolated patellofemoral osteoarthritis will be included. Intra-operatively, rotation of the femoral component will be assessed using anatomical landmarks including the epicondylar axis, Whiteside’s line, and lower leg axis. The aim is to insert the femoral component between 3 and 6 degrees external rotation relative to the transepicondylar axis. Two experienced musculoskeletal radiologists will measure the angle between the transepicondylar axis and the femoral component, two to three days after surgery. The primary outcome is the CT-based femoral component rotation of the prosthesis relative to the transepicondylar axis. The secondary outcome is the patient reported KOOS questionnaire at 1-year follow-up.

Successful completion of this study will provide data on the actual amount of femoral component rotation in patellofemoral joint replacement, and its relationship with clinical results. (Netherlands Trial Register NTR4175).

Patellofemoral arthroplasty for symptomatic nonunion after trochlear osteotomy for patellar instability: a case report

INTRODUCTION

Patients with patellofemoral instability with trochlear dysplasia may be treated with trochlear osteotomy.

CASE PRESENTATION

We present a patient with patellofemoral instability treated with trochlear osteotomy. The procedure resulted in nonunion with painful bony impingement and isolated patellofemoral osteoarthritis. Patellofemoral arthroplasty was performed.

CONCLUSION

Patellofemoral arthroplasty may be considered a salvage procedure for failed surgical treatment for trochlear dysplasia.