Slipped capital femoral epiphysis. The prevalence of late contralateral slip

Rate and Risk Factors for Contralateral Slippage in Adolescents Treated for Slipped Capital Femoral Epiphysis: A Comprehensive Analysis of 3,528 Cases

BACKGROUND

After a unilateral slipped capital femoral epiphysis (SCFE), the contralateral hip is at risk for a subsequent SCFE. However, further information with regard to risk factors involved in the development of contralateral SCFE must be investigated. The purpose of this study was to report the rate and risk factors for subsequent contralateral SCFE in adolescents treated for unilateral SCFE by exploring a mix of known and potential risk factors.

METHODS

A case-control study utilizing aggregated multi-institutional electronic medical record data between January 2003 and March 2023 was conducted. Patients <18 years of age diagnosed with SCFE who underwent surgical management were included. Variables associated with contralateral SCFE were identified using multivariable logistic regression models that adjusted for patient characteristics and time of the surgical procedure, providing adjusted odds ratios (ORs). The false discovery rate was accounted for via the Benjamini-Hochberg method.

RESULTS

In this study, 15.3% of patients developed contralateral SCFE at a mean (and standard error) of 296.53 ± 17.23 days and a median of 190 days following the initial SCFE. Increased thyrotropin (OR, 1.43 [95% confidence interval (CI), 1.04 to 1.97]; p = 0.022), diabetes mellitus (OR, 1.67 [95% CI, 1.22 to 2.49]; p = 0.005), severe obesity (OR, 1.81 [95% CI, 1.56 to 2.57]; p < 0.001), history of human growth hormone use (OR, 1.85 [95% CI, 1.10 to 3.38]; p = 0.032), low vitamin D (OR, 5.75 [95% CI, 2.23 to 13.83]; p < 0.001), younger age in boys (under 12 years of age: OR, 1.85 [95% CI, 1.37 to 2.43]; p < 0.001) and in girls (under 11 years of age: OR, 1.47 [95% CI, 1.05 to 2.02]; p = 0.026), and tobacco exposure (OR, 2.43 [95% CI, 1.49 to 3.87]; p < 0.001) were significantly associated with increased odds of developing contralateral SCFE.

CONCLUSIONS

In the largest study on this topic, we identified the rate, odds, and risk factors associated with development of contralateral SCFE. We found younger age, hypothyroidism, severe obesity, low vitamin D, diabetes mellitus, and a history of human growth hormone use to be independent risk factors. Our findings can aid clinical decision-making in at-risk patients.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Prophylactic fixation of the unaffected contralateral side in children with slipped capital femoral epiphysis seems favorable: A systematic review

BACKGROUND

Slipped capital femoral epiphysis (SCFE) occurs in adolescents and has an incidence of around 10 per 100000 children. Children presenting with a unilateral SCFE are 2335 times more likely to develop a contralateral SCFE than the general population. Prognostic factors that have been suggested to increase the risk of contralateral slip include a younger patient, an underlying endocrine disorder, growth hormone use and a higher radiographic posterior sloping angle. However, there is still much debate on the advantages and disadvantages of prophylactic fixation of the unaffected side in an otherwise healthy patient.

AIM

To investigate the risk rate of contralateral SCFE and assess the (dis)advantages of prophylactic fixation of the contralateral hip.

METHODS

A systematic literature search was performed in the Embase, Medline, Web of Science Core Collection and Cochrane databases. Search terms included ‘slipped capital femoral epiphysis,’ ‘fixation,’ ‘contralateral,’ and derivatives. The eligibility of the acquired articles was independently assessed by the authors and additional relevant articles were included through cross-referencing. Publications were considered eligible for inclusion if they presented data about otherwise healthy children with primarily unilateral SCFE and the outcomes of prophylactically pinning their unaffected side, or about the rates of contralateral slips and complications thereof. The study quality of the included articles was assessed independently by the authors by means of the methodological index for non-randomized studies criteria.

RESULTS

Of 293 identified unique publications, we included 26 studies with a total of 12897 patients. 1762 patients (14%) developed a subsequent symptomatic contralateral slip. In addition, 38% of patients developed a subsequent slip on the contralateral side without experiencing clinical symptoms. The most outspoken advantage of prophylactic fixation of the contralateral hip in the literature is prevention of an (asymptomatic) slip, thus reducing the increased risk of avascular necrosis (AVN), cam morphology and osteoarthritis. Disadvantages include an increased risk of infection, AVN, peri-implant fractures, loss of fixation as well as migration of hardware and morphologic changes as a consequence of growth guidance. These risks, however, appeared to only occur incidentally and were usually mild compared to the risks involved with an actual SCFE.

CONCLUSION

The advantages of prophylactic pinning of the unaffected side in otherwise healthy patients with unilateral SCFE seem to outweigh the disadvantages. The final decision for treatment remains to be patient-tailored.

Epiphyseal Angulation and Related Spatial Orientation in Slipped Capital Femoral Epiphysis: Theoretical Model and Biomechanical Explanation of Varus and Valgus Slip

The management of slipped capital femoral epiphysis (SCFE) is controversial. Surgical decision-making is based regularly on the chronicity, stability, and severity of the slip. The purpose of this study was to determine the true angulation and spatial orientation of the epiphysis in hips with SCFE and contralateral hips.

METHODS

Eighteen hips in 18 patients with SCFE were included in the analysis. Trigonometric calculations, based on angle measurements using 2 conventional radiographs in planes that are perpendicular to each other, were used to determine the angulation of the epiphysis and its orientation in space.

RESULTS

The mean absolute epiphyseal obliquity of the SCFE hips was 56.2° and the spatial orientation was 36.5°. The mean obliquity of the contralateral side was 34.0°, with a related spatial orientation of 16.8°. The maximum error can reach up to 9.9° (or 41%) when comparing the calculated angles with the angle measurements on radiographs.

CONCLUSIONS

On standard radiographs, the epiphyseal angulation in SCFE is consistently underestimated. As a consequence, the assigned classification of some patients may be 1 severity group too low, which impacts the value of traditional severity classification for surgical decision-making. The analysis of the spatial orientation of the slip with the concomitant direction of the resultant shear can partially explain varus and valgus slip in SCFE.

LEVEL OF EVIDENCE

Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Rates of Contralateral SCFE in the United States: Analysis of the Pediatric Health Information System

BACKGROUND

Slipped capital femoral epiphysis (SCFE) is relatively common in pediatric patients. Subsequent contralateral SCFE is also common and rates of bilateral SCFE have been reported to range from 12% to 80% in the literature. The purpose of this study was to determine the rates of subsequent contralateral SCFE in patients who present with unilateral SCFE in the United States and determine risk factors for the development of subsequent contralateral SCFE.

METHODS

The authors performed a retrospective study using data from the Pediatric Health Information System (PHIS). Patients who underwent in situ pinning of a unilateral SCFE between 2004 and 2016 were included in this study and followed prospectively to determine subsequent contralateral SCFE. They excluded patients who underwent bilateral pinning at index admission. Descriptive, univariate, and multivariate statistics were used to determine rates of subsequent contralateral SCFE and identify factors associated with contralateral SCFE.

RESULTS

This study included 9755 patients who underwent in situ pinning for unilateral SCFE. The mean age at the time of index SCFE was 11.9 years (SD, 1.7) and ~62% of patients were male individuals. Subsequent contralateral SCFE occurred in 1077 (11%) patients at an average of 277 days (range, 7 to 1523 d) after the index procedure. Patients who developed a subsequent contralateral SCFE were younger at the time of index SCFE than patients who did not develop a contralateral SCFE (11.3 vs. 12 y old, P<0.01). In multivariate analysis, older children had a lower risk of subsequent contralateral SCFE (adjusted odds ratio, 0.8; 95% confidence interval, 0.77-0.83), and the odds of subsequent contralateral SCFE decreased by 20% with each increasing year in age.

CONCLUSIONS

The rate of subsequent contralateral SCFE is ~11% in the United States, and younger patients are more likely to develop a contralateral SCFE than older patients. Prophylactic pinning should be considered in younger patients with unilateral SCFE, and patients should be followed until skeletal maturity to monitor for subsequent contralateral SCFE.

LEVEL OF EVIDENCE

Level III.

Risk Factors for Contralateral Slipped Capital Femoral Epiphysis: A Meta-analysis of Cohort and Case-control Studies

BACKGROUND

Slipped capital femoral epiphysis (SCFE) is an important cause of hip pain and disability in pediatric patients. SCFE occurs bilaterally in 12% to 80% of cases, and the risk of contralateral SCFE is noted to be 2335 times higher than the index SCFE. Several studies have reported risk factors for contralateral SCFE; however, these studies have not been systematically analyzed. The purpose of this systematic review and meta-analysis was to review and analyze risk factors for subsequent contralateral SCFE and identify the strongest risk factors for a subsequent slip.

METHODS

A systematic review was performed of all observational studies focusing on risk factors for subsequent contralateral SCFE indexed in Medline, Embase, and Cochrane databases. Data extraction was performed and summarized using descriptive statistics. Meta-analysis was performed for risk factors with sufficient constituent study data. Quality assessment was performed using the Newcastle-Ottawa Scale, and funnel plots were generated to assess publication bias.

RESULTS

The initial search strategy identified 226 references, and after exclusions, 20 studies were included in this analysis. Demographic risk factors included age, sex, weight, body mass index, ethnicity, and urban/rural residence; clinical risk factors included endocrine abnormality, duration of symptoms, slip stability, and slip chronicity; and radiographic risk factors included slip angle, triradiate cartilage, alpha angle, posterior sloping angle (PSA), physeal sloping angle, modified Oxford score, and bone age. Younger patient age, body mass index≥95th percentile, presence of an endocrine abnormality, higher PSA of the unaffected hip, and lower modified Oxford score have been noted to be significant risk factors for contralateral SCFE. Meta-analysis showed that younger age (-0.9; confidence interval, -1.1, -0.6), and higher PSA (4.7 degrees; 95% confidence interval, 3.3-6.2 degrees) of the unaffected hip were predictive of subsequent contralateral SCFE. The majority of studies were of good quality.

CONCLUSION

There are several risk factors for subsequent contralateral SCFE. On the basis of the available data, younger patients with a high PSA of the unaffected hip would most likely benefit from prophylactic fixation of the unaffected hip.

LEVEL OF EVIDENCE

Level II.

Contralateral slip after unilateral slipped capital femoral epiphysis is associated with acetabular retroversion but not increased acetabular depth and overcoverage

Overcoverage of the femoral head by the acetabulum, increased acetabular depth and retroversion have been associated with the etiology of slipped capital femoral epiphysis (SCFE). However, limited evidence exists about the impact of the acetabular morphology on the development of a contralateral slip following an initial presentation of unilateral SCFE. We aimed to investigate whether acetabular overcoverage as assessed by an increased lateral center-edge angle (LCEA) and low Tönnis angle, increased acetabular depth assessed by the acetabular depth-width ratio (ADR) and the presence of coxa profunda; and acetabular retroversion assessed by the presence of the crossover sign were associated with a contralateral slip in patients presenting with unilateral SCFE. We evaluated 250 patients with initial diagnosis of unilateral SCFE (average age, 12.5 ± 1.7 years), who had not undergone prophylactic fixation on the contralateral hip for a median follow-up of 49 months (interquartile range: 25-76 months). Endpoints were the development of a contralateral slip (70 patients, 28%) or skeletal maturity assessed by complete closure of the proximal femoral growth plate (180 patients, 72%). We measured the LCEA, Tönnis angle, ADR, and the coxa profunda sign on an anteroposterior pelvic radiograph. The crossover sign was assessed in 208 hips who had a secondary ossification center in the posterior acetabular rim. For each additional degree of LCEA, the odds of contralateral slip decreased 8% [odds ratio = 0.92; 95% confidence interval (CI), 0.87-0.98; P = 0.009]. Tönnis angle (P = 0.11), ADR (P = 0.20) and coxa profunda (p = 0.37) had no association with a contralateral slip. The presence of crossover sign increased two and half times the odds for a contralateral slip (odds ratio = 2.5; 95% CI = 1.12-5.64; P = 0.03). Acetabular retroversion, but not acetabular overcoverage or increased acetabular depth, was associated with contralateral SCFE development in patients with unilateral SCFE. Level of evidence: prognostic level II.

Predicting subsequent contralateral slipped capital femoral epiphysis: an evidence-based approach

PURPOSE

The purpose of this study was to identify risk factors for developing a subsequent contralateral slipped capital femoral epiphysis (SCFE) and provide a prediction score to quantify risk of subsequent slip at the time of initial presentation.

METHODS

This retrospective study included patients that presented with a unilateral SCFE between 2006 and 2017. Chart and radiographic review were performed to collect demographic, clinical and radiographic risk factors. Descriptive statistics, univariate analyses and multivariate regression analysis were used to compare risk factors between patients that did or did not develop a subsequent contralateral SCFE.

RESULTS

This study included 183 patients and 33 patients (18%) developed a subsequent contralateral SCFE. Younger age at time of initial presentation, lower modified Oxford Score and smaller difference in epiphyseal-diaphyseal angle between both sides during index presentation were significant predictors of subsequent contralateral SCFE. Specifically, age ≤ 11 years, modified Oxford Score ≤ 20 and difference in epiphyseal-diaphyseal angle of ≤ 21° between both hips were predictive of a contralateral slip (Area Under the Curve = 0.78; p < 0.05). The presence of each risk factor increased the risk of subsequent contralateral SCFE and having all three risk factors increased the risk to 73%.

CONCLUSION

There is a significant risk of subsequent contralateral SCFE in patients with unilateral SCFE, and predictive risk factors include younger age, lower modified Oxford Score and smaller difference in epiphyseal-diaphyseal angle between the affected and unaffected hips.

LEVEL OF EVIDENCE

Level III.

Predicting Risk of Contralateral Slip in Unilateral Slipped Capital Femoral Epiphysis: Posterior Epiphyseal Tilt Increases and Superior Epiphyseal Extension Reduces Risk

BACKGROUND

Femoral morphology may influence the etiology of slipped capital femoral epiphysis (SCFE). We investigated whether radiographic parameters of femoral head-neck morphology are associated with a subsequent contralateral slip in patients presenting with unilateral SCFE.

METHODS

We evaluated 318 patients treated for unilateral SCFE between 2000 and 2017. There were 145 males (46%), and the mean age in the series was 12.4 ± 1.7 years. The patients were followed for a minimum of 18 months or until the development of a contralateral slip (70 patients, 22%). We measured the epiphyseal tilt, epiphyseal extension ratio, alpha angle, and epiphyseal angle of the uninvolved, contralateral hip at initial presentation. Multivariable logistic regression analysis was used to assess whether femoral measurements were associated with the occurrence of a contralateral slip. Receiver operating characteristic (ROC) curves were used to determine optimal thresholds of radiographic measures to determine an increased risk of a contralateral slip. A number-needed-to-treat (NNT) analysis was conducted to evaluate the effectiveness of the femoral measurement thresholds in preventing a contralateral slip.

RESULTS

Multivariable analysis, controlling for triradiate cartilage status, identified the lateral tilt angle and the superior epiphyseal extension ratio as independent factors associated with the likelihood of a contralateral slip. For each additional degree of posterior tilt, the odds of a contralateral slip increase by 8% (odds ratio [OR] = 1.08; 95% confidence interval [CI] = 1.02 to 1.14; p = 0.008), and for each 0.01 increase in the superior epiphyseal extension ratio, the odds of a contralateral slip decrease by 6% (OR = 0.94; 95% CI = 0.88 to 0.99; p = 0.03). A threshold for the epiphyseal tilt of 10° corresponded to a predicted probability of a contralateral slip of 54% in patients with open triradiate cartilage and an NNT of 3.3.

CONCLUSIONS

In patients presenting with unilateral SCFE, a higher posterior tilt of the epiphysis increases the risk while an increased superior extension of the epiphysis reduces the risk of a contralateral slip. Our findings may assist the discussion about contralateral prophylactic pinning in patients with unilateral SCFE.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Imaging of the limping child

Limping is a challenging symptom in the pediatric patient as the diagnosis can range from traumatic, malformative, infectious/inflammatory and neoplastic diseases. In this paper, we propose a schematic imaging algorithm to the limping child in three different age groups (Toddler: 1-3years, child: 4-10 years; adolescent: 11-16 years) based on presence of signs of infection, any specific localization of pain, and history of trauma. In this setting, the most common imaging pitfalls are also summarised. Finally, a literature review of the main differential causes of limping in the pediatric patient is reported.

Morphologic Features of the Contralateral Femur in Patients With Unilateral Slipped Capital Femoral Epiphysis Resembles Mild Slip Deformity: A Matched Cohort Study

BACKGROUND

Hip osteoarthritis has been reported in the contralateral hip in patients who had been treated for unilateral slipped capital femoral epiphysis (SCFE) during adolescence. Although this might be related to the presence of a mild deformity, the morphologic features of the contralateral hip in unilateral SCFE remains poorly characterized.

QUESTIONS/PURPOSES

Do measurements of (1) femoral head-neck concavity (α angle and femoral head-neck offset), (2) epiphyseal extension into the metaphysis (epiphyseal extension ratio and epiphyseal angle), and (3) posterior tilt of the epiphysis (epiphyseal tilt angle) differ between the contralateral asymptomatic hips of patients treated for unilateral SCFE and hips of an age- and sex-matched control population without a history of hip disease?

METHODS

From January 2005 to May 2015, 442 patients underwent surgical treatment for SCFE at our institution. Patients were included in this study if they had a pelvic CT scan and unilateral SCFE defined by pain or a limp in one hip without symptoms or obligatory external rotation with flexion in the contralateral hip and no evidence of SCFE findings on available radiographs. Seventy-two (16%) patients had a pelvic CT scan; however, 32 patients with bilateral involvement and one patient with CT imaging of inadequate quality for multiplanar reformatting were excluded. Thirty-nine control subjects were identified from a preexisting database of patients who underwent pelvic CT between January 2008 and January 2014 for assessment of abdominal pain in the setting of suspected appendicitis. Patients in the contralateral asymptomatic hip group then were matched to control subjects using a modified nearest-neighbor approach based on sex and age. Patients in the contralateral asymptomatic hip group were separated in males and females and control subjects were assigned to an appropriate sex category. Then subjects closest in age were matched with each patient. If more than one subject was available as a match for a given patient, the control subject with the closest BMI was selected. The contralateral asymptomatic hip and matched groups had 19 (49%) male patients and 20 (51%) female patients, with mean ages (± SD) of 16 (± 3) years and 16 (± 3) years, respectively (p = 0.16). Matched subjects had a mean BMI of 25 ± 4 kg/m and the mean BMI difference among groups was 5 ± 5 kg/m (p < 0.001). According to the Southwick radiographic criteria nine patients (23%) had a mild slip, 10 (26%) had a moderate slip, and 19 (49%) had severe SCFE. The α angle and femoral head-neck offset, epiphyseal extension ratio and epiphyseal angle, and epiphyseal tilt were assessed in the anterior, anterosuperior, and superior femoral planes on radially reformatted CT by one observer not involved in clinical care of the patients. Inter- and intrarater reliability were determined on 10 randomly selected hips assessed by the same observer and another observer and it was found to be excellent for all femoral measurements (intraclass correlation coefficients > 0.85). Paired t-tests were used to compare the contralateral asymptomatic hip of patients with SCFE and control hips.

RESULTS

The head-neck junction showed decreased concavity in the contralateral femur of patients with unilateral SCFE compared with control subjects as assessed by slightly higher mean α angle in the anterosuperior plane (51° ± 6° versus 48° ± 7°; mean difference, 2°, 95% CI, 0°-5°; p = 0.04) and slightly higher median α angle in the superior plane (45° [range 37°-72°] versus 42° [range, 36°-50°], median shift, 4° [range, 2°-5°], p < 0.001), and slightly lower head-neck offset (anterosuperior: 5 mm ± 2 mm versus 6 mm ± 2 mm, mean difference, -1mm [range, -1 mm to 0 mm], p = 0.009; superior: median, 6 mm [range, 1 mm-8 mm] versus 7 mm [range, 5 mm-9 mm]; median shift, -1 mm [range, -1 mm to 0 mm], p < 0.001). There was less epiphyseal extension in the anterosuperior plane as evidenced by lower epiphyseal extension ratio (72% ± 6% versus 75% ± 6%; p = 0.005) and higher epiphyseal angle (64° ± 7° versus 60° ± 7°; p = 0.003). The epiphysis was slightly more posteriorly tilted (anterior plane tilt: 8° ± 6° versus 5° ± 4°; p = 0.03) and more vertically oriented (superior plane tilt 11° ± 5° versus 14° ± 4°; p = 0.006) in the contralateral asymptomatic hip of patients with SCFE.

CONCLUSIONS

The contralateral femur in patients treated for unilateral SCFE shows decreased concavity of the head-neck junction assessed by a higher α angle and reduced head-neck offset compared with age- and sex-matched control subjects. Because we noted lower epiphyseal extension but a more posteriorly tilted epiphysis, the reduced concavity resembles a mild slip deformity rather than an idiopathic cam morphologic feature.

CLINICAL RELEVANCE

Although we noted a difference in the morphologic features of the head-neck junction between the two groups, the clinical significance is unclear because most differences were rather small. However, our findings suggest that the uninvolved hip in patients with unilateral SCFE may have a subtle asymptomatic cam morphologic feature that may be identified only with advanced imaging (CT or MRI). Future studies should investigate whether these morphologic changes influence development of contralateral SCFE or symptomatic femoroacetabular impingement in the contralateral hip of patients with unilateral SCFE and establish thresholds for indication of prophylactic fixation to avoid further slip and worsening of the morphologic features of the cam-femoroacetabular impingement.

No influence of femoral component rotation by the lateral femoral posterior condylar cartilage remnant technique on clinical outcomes in navigation-assisted TKA

PURPOSE

To investigate whether cartilage thickness in the lateral femoral posterior condyle affects the femoral rotation angles on navigation and clinical outcomes of navigation-assisted total knee arthroplasty (TKA).

METHODS

This is a prospective randomized study of navigation-assisted TKA. Fifty cases underwent TKA without removal of the lateral posterior femoral cartilage (Group 1), and 56 cases underwent TKA with removal of the lateral posterior femoral cartilage (Group 2). The femoral rotation was evaluated using CT and compared with navigation values. The angle between the clinical transepicondylar axis and posterior condylar axis measured on CT was defined as the femoral rotation angle on CT. Elevation of the joint line and patellar measurements were also evaluated.

RESULTS

The clinical outcomes were not statistically different in the two groups. The radiographic measurements were not statistically different except femoral rotation angle on navigation. The mean femoral rotation angle of navigation was 4.0° ± 2.2° without cartilage removal and 5.1° ± 2.5° with cartilage removal. The reliability and validity were high between the femoral rotation angle on navigation in the cartilage removal group and that on CT, but there were no differences in clinical outcomes between the two groups.

CONCLUSION

There was little effect of navigation-assisted TKA on radiographic and clinical outcomes, although femoral rotational differences were caused by the lateral femoral posterior condylar cartilage. Although the rotational differences due to cartilage would be within the clinical safety margin, surgeons should consider that difference during TKA.

LEVEL OF EVIDENCE

Lower quality randomized trial (no masking), Level II.

Total knee arthroplasty in patients with Ranawat type-II valgus arthritic knee with a marked coronal femoral bowing deformity: comparison between computer-assisted surgery and intra-articular resection

Background

Proper limb and component alignments as well as soft tissue balance are vital for the longevity and optimal long-term outcomes of total knee arthroplasty (TKA). This procedure is technically demanding in patients with Ranawat type-II valgus arthritic knees with marked coronal femoral bowing. Computer-assisted surgery (CAS) and intra-articular bone resection with TKA are the treatments of choice for patients with ipsilateral extra-articular deformity. In theory, both CAS and intra-articular bone resection are beneficial in Ranawat type-II valgus arthritic knees with marked coronal femoral bowing deformity, but the literature on this topic is sparse. We compared the benefits of using these two techniques for TKA under this circumstance.

Methods

Patients who had Ranawat type-II valgus arthritic knees and marked coronal femoral bowing deformity and had undergone TKA at our hospital between 2005 and 2013 were enrolled in this retrospective study. Patients treated with CAS were assigned to the CAS-TKA group; patients treated with intra-articular bone resection were assigned to the Bone-Resect-TKA group. Radiographic parameters and clinical outcomes (International Knee Society (IKS) scores and patellar scores) in both groups were compared.

Results

Forty-seven patients (50 knees) met the inclusion criteria: 22 knees in the CAS-TKA group and 28 knees in the Bone-Resect-TKA group. Lateral retinaculum release was significantly (P = 0.008) higher in the Bone-Resect-TKA group. The joint-line was significantly properly restored in the CAS-TKA group (P = 0.011). The reconstructed mechanical axis was significantly (P = 0.012) closer to normal in the CAS-TKA group than in the Bone-Resect-TKA group. For component alignment, the femoral valgus and femoral flexion angles were significantly better in the CAS-TKA group (P = 0.002 and P = 0.006, respectively), but not the tibial valgus, tibial flexion, or patellar tilting angles. IKS scores and patellar scores were not significantly different between groups at a mean follow-up of 60.2 months.

Conclusions

CAS-TKA was effective for obtaining proper alignment and joint-line restoration in patients with Ranawat type-II valgus arthritic knees and marked coronal femoral bowing deformity, but not for yielding better clinical outcomes. Additional large-scale prospective randomized cohort studies with long-term follow-ups are necessary to make evidence-based recommendations.

Is patellar denervation necessary in total knee arthroplasty without patellar resurfacing?

PURPOSE

To conduct a meta-analysis with randomized controlled trials (RCTs) published in full text to determine the effectiveness of patellar denervation (PD) in primary total knee arthroplasty (TKA).

METHODS

Literature search was performed in PubMed, Embase, Web of Science and Cochrane Library for information from the earliest date of data collection to February 2015. RCTs comparing the benefits and risks of PD with those of no patellar denervation (NPD) in primary TKAs were included. Statistical heterogeneity was quantitatively evaluated by X(2) test with the significance set P < 0.10 or I (2) > 50 %.

RESULTS

Six RCTs consisting of 751 patients were included. The incidences of AKP in PD group and NPD group were 38.3 % (90/235) and 46.3 % (107/231), respectively. Meta-analysis showed significant prevention effect of PD on the incidence of AKP (OR 0.65; 95 % CI 0.42, 1.00; P = 0.05) without significant heterogeneity (I (2) = 44 %, P = 0.15). Our results also indicated that PD was significantly associated with better American Knee Society knee (WMD = 2.50; 95 % CI 0.34, 4.67; P = 0.02) and functional scores (WMD = 4.07; 95 % CI 1.34, 6.80; P = 0.0003) and range of motion (ROM) (WMD = 4.27; 95 % CI 1.95, 6.60; P = 0.0003) compared with NPD. However, there was no significant difference between the two groups no matter in Oxford knee score, patellar score or visual analogue scale at any other time. Complications and revisions did not differ significantly between the two groups.

CONCLUSION

This meta-analysis showed that PD in TKAs without patellar resurfacing, compared with NPD, could prevent the incidence of post-operative AKP and improve clinical outcome in KSS and post-operative ROM. Based on the above results, PD was a safe procedure with no significant complications and revision or re-operations.

LEVEL OF EVIDENCE

Therapeutic study, Level II.

Active Flexion in Weight Bearing Better Correlates with Functional Outcomes of Total Knee Arthroplasty than Passive Flexion

PURPOSE

Correlations between maximum flexion and functional outcomes in total knee arthroplasty (TKA) patients are reportedly weak. We investigated whether there are differences between passive maximum flexion in nonweight bearing and other types of maximum flexion and whether the type of maximum flexion correlates with functional outcomes.

MATERIALS AND METHODS

A total of 210 patients (359 knees) underwent preoperative evaluation and postoperative follow-up evaluations (6, 12, and 24 months) for the assessment of clinical outcomes including maximum knee flexion. Maximum flexion was measured under five conditions: passive nonweight bearing, passive weight bearing, active nonweight bearing, and active weight bearing with or without arm support. Data were analyzed for relationships between passive maximum flexion in nonweight bearing by Pearson correlation analyses, and a variance comparison between measurement techniques via paired t test.

RESULTS

We observed substantial differences between passive maximum flexion in nonweight bearing and the other four maximum flexion types. At all time points, passive maximum flexion in nonweight bearing correlated poorly with active maximum flexion in weight bearing with or without arm support. Active maximum flexion in weight bearing better correlated with functional outcomes than the other maximum flexion types.

CONCLUSIONS

Our study suggests active maximum flexion in weight bearing should be reported together with passive maximum flexion in nonweight bearing in research on the knee motion arc after TKA.

[Macroscopic and functional anatomy of the apophyseal plate]

Apophyses are growth zones attached to the shaft (corpus) of larger bones. They vary in size and develop their own ossification centres or form as part of an usually fibrocartilaginous tendon or ligament insertion. The structure of the cartilaginous apophyseal plate is very similar to that of an epiphyseal growth plate and like these they are adapted to withstand perpendicular compressive forces without becoming harmed. This is best highlighted by the fact that their mineralized borders always orient themselves perpendicular to the overall resulting force vector. The edges of the apophyseal plates are characteristically bent which allows them to resist moderate shear forces. Like the epiphyseal plates the apophyseal plates exhibit a zonal organization which is not very well adapted to permanently withstand shear forces, especially if they occur under dynamic conditions. In these situations the tendinous insertions with their collagen fibre anchoring system have to provide compensation when balancing the load transmitted across the system.

Analysis on the risk of contralateral proximal femoral epiphyseal slippage using the modified Oxford score

Objective

To determine the application of the modified Oxford score among patients with proximal femoral epiphyseal slippage (PFES) as an aid to indicating prophylactic surgical treatment on the contralateral hip.

Methods

Retrospective analysis on the medical files of patients attended at the institution where the authors work. From these, patients attended between 2008 and 2011 who presented unilateral PFES and were followed up for a minimum of two years were selected. Patients were excluded if they presented endocrine disease, metabolic disease, Down syndrome or radiographs that were inadequate for determining the modified Oxford score. The initial radiographs received scores ranging from 16 to 26. Statistical analysis was used to determine whether the scoring was predictive of future development of contralateral slippage.

Results

Among the 15 patients with unilateral PFES that were selected, five (33.3%) evolved with contralateral slippage. The patients were divided into two groups. Four patients were considered to present risk and three of them developed contralateral slippage. In the group that was considered not to present risk, there were 11 patients and two of these evolved with contralateral slippage. Thus, there was a tendency for the patients in the group that developed the disease to differ from the group that did not develop it, in relation to the risk classification.

Conclusion

Although application of the modified Oxford score was not statistically significant in our sample, we noted a tendency toward contralateral slippage among hips with low scores.

Comparison of patellar resurfacing versus preservation in high flexion total knee arthroplasty

PURPOSE

Recently, high flexion design total knee arthroplasty (TKA) has been introduced to improve clinical outcomes. The purpose of this study is to compare the midterm outcomes between patellar resurfacing (PR) and patellar preservation (PP) in high flexion TKA.

METHODS

A total of 373 knees of primary TKAs were performed using high flexion design, 339 knees involved PR group and 34 knees involved PP group. After applying exclusion criteria, 1:3 matching was performed by the matching criteria. After matching, 69 knees in PR group and 23 knees in PP group remained. Radiographic outcomes, clinical outcomes, patients' satisfaction, ability and pain related to the high flexion activities were also evaluated.

RESULTS

There was no significant difference in radiograph measurements, KS function score and WOMAC score (n.s). However, PR group showed better outcomes in KS knee score (P = 0.001) and HSS score (P = 0.03). There was no significant difference in postoperative satisfaction and ability of high flexion activities between the groups, but the pain at the high flexion activities in PP group was worse than that in PR group.

CONCLUSION

In high flexion design of TKA, PR resulted in better midterm outcomes in regard to KS knee score, HSS score and knee pain related to the high flexion activities. The selective PR is recommended when performing primary TKA with high flexion design.

LEVEL OF EVIDENCE

IV.

Residual knee pain and functional outcome following total knee arthroplasty in osteoarthritic patients

PURPOSE

Total knee arthroplasty (TKA) is a successful and safe elective operation in managing patients with severe osteoarthritis of the knee. However, the presence of residual knee pain (RKP) post-TKA can adversely affect patient satisfaction and functional outcome. Hence, the aim of this paper is to identify the incidence, progression of knee pain, functional outcome post-TKA and possible predictive factors for the development of RKP post-TKA.

METHODS

A retrospective review of 357 patients was conducted with a minimum follow-up period of 2 years. Predictive factors reviewed include the patients' demographics, co-morbidities, type of implants and patellar management. For functional outcome, the patient's Knee Society Score (KSS) and Western Ontario and McMaster Universities Index of Osteoarthritis scores were analysed. To determine presence and severity of RKP, the sub-score for pain in the KSS was utilised.

RESULTS

In total, 31.1 and 28.9% of the patients were found to have RKP at 1 and 2 years, respectively, though their functional outcome scores continued improving from 1 year. Ischaemic heart disease (IHD) patients were more likely to have RKP and poorer functional outcome at 1 year. Males and patients with posterior-stabilised implants were found to have better functional outcome at 1 and 2 years, respectively.

CONCLUSIONS

Almost a third of the patients continued to have RKP at 2 years post-TKA, with factors such as gender, presence of IHD and implant type significantly associated with the development of RKP and/or poorer functional outcome scores. By recognising the incidence and predictive factors for RKP, physicians will be able to better manage their patients' expectations and optimise their pre-morbid status pre-operatively.

LEVEL OF EVIDENCE

III.

Patellofemoral resurfacing and patellar denervation in primary total knee arthroplasty

PURPOSE

To conduct a systematic review and network meta-analysis of randomized controlled trials (RCTs) with the aim of comparing relevant clinical outcomes between patellar denervation, resurfacing and non-resurfacing.

METHODS

A database search was performed using PubMed and Scopus search engines. RCTs or quasi-experimental designs comparing clinical outcomes between treatments by a search of articles dated from inception to October 23, 2012. Unstandardized mean difference (UMD) and random effects methods were applied for pooling continuous and dichotomous outcomes, respectively. A longitudinal mixed regression model was used for network meta-analysis to indirectly compare treatment effects.

RESULTS

Eighteen of 315 studies identified were eligible. Compared with patellar non-resurfacing, patellar denervation had a UMD that displayed a significant improvement in symptoms with values in pain visual analog score (VAS) and Knee Society Score (KSS) of -0.6 [95% confidence interval (CI) -1.13, -0.25] and 2.55 (95% CI 0.43, 4.68), respectively. The UMD in VAS, KSS, and Knee Function Score (KFS) in patellar resurfacing showed no significant improvement in symptoms when compared to non-resurfacing. Patients who underwent surgery with patellar resurfacing had a lower reoperation rates with pooled relative risks (RRs) of 0.69 (95% CI 0.50, 0.94) when compared to non-resurfacing. The network meta-analysis suggested a benefit of borderline significance for patellar denervation with a pooled RR of 0.63 (95% CI 0.38, 1.03), showing that there is a lower chance of anterior knee pain when compared to non-resurfacing. Patellar resurfacing also displays a significantly lower chance of reoperation with a pooled RR of 0.68 (95% CI 0.50, 0.92) when compared to non-resurfacing. Multiple active treatment comparisons indicated that patellar denervation resulted in greater improvement in KFS than patellar resurfacing.

CONCLUSION

This review suggests that either patellar denervation or patellar resurfacing may be selected for the management of the patellofemoral component in total knee replacement. Patellar denervation may help improve postoperative knee function, but does not improve pain when compared to patellar resurfacing.

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.

Slipped capital femoral epiphysis: how to evaluate with a review and update of treatment

Slipped capital femoral epiphysis (SCFE) involves displacement of the proximal femoral metaphysis relative to a fixed epiphysis, usually during a period of rapid growth and unique physeal susceptibility. Patients have characteristic clinical, histologic, and radiologic features. Several clinical signs and medical diagnoses should prompt radiologic and laboratory workup. Limp or hip or knee pain in a patient 10 to 16 years old should include SCFE in the differential. If confirmed, appropriate treatment involves proximal femoral physeal stabilization and/or realignment. The optimal surgical treatment of severe SCFE and its late sequela remain an evolving and controversial subject.

Patellar denervation with electrocautery in total knee arthroplasty without patellar resurfacing: a meta-analysis

PURPOSE

The impact of patellar denervation with electrocautery in total knee arthroplasty (TKA) on post-operative outcomes has been under debate. This study aims to conduct a meta-analysis and systematic review to compare the benefits and risks of circumpatellar electrocautery with those of non-electrocautery in primary TKAs.

METHODS

Comparative and randomized clinical studies were identified by conducting an electronic search of articles dated up to September 2012 in PubMed, EMBASE, Scopus, and the Cochrane databases. Six studies that focus on a total of 849 knees were analysed. A random-effects model was conducted using the inverse-variance method for continuous variables and the Mantel-Haenszel method for dichotomous variables.

RESULTS

There was no significant difference in the incidence of anterior knee pain between the electrocautery and non-electrocautery groups. In term of patellar score and Knee Society Score, circumpatellar electrocautery improved clinical outcomes compared with non-electrocautery in TKAs. The statistical differences were in favour of the electrocautery group but have minimal clinical significance. In addition, the overall complications indicate no statistical significance between the two groups.

CONCLUSIONS

This study shows no strong evidence either for or against electrocautery compared with non-electrocautery in TKAs.

LEVEL OF EVIDENCE

Therapeutic study (systematic review and meta-analysis), Level III.

The patella in total knee arthroplasty: to resurface or not is the question

The decision to resurface the patella during total knee arthroplasty remains controversial. Even though some surgeons routinely resurface the patella to avoid the increased rates of postoperative anterior knee pain and reoperation for secondary resurfacing, others selectively resurface based on the presence of anterior knee pain, notably damaged articular cartilage, inflammatory arthritis, isolated patellofemoral arthritis, and patellar subluxation and maltracking. The anatomy and biomechanics of the patellofemoral joint, combined with advances in surgical technique and prostheses must be taken into account when making a decision to resurface the patella. Accurate component implantation is imperative for a successful outcome if the patella is resurfaced.

Subclinical bilateral involvement of the hip in patients with slipped capital femoral epiphysis: a multicentre study

PURPOSE

This study was conducted to assess the posterior inclination of the contralateral femoral epiphysis in patients with unilateral slipped capital femoral epiphysis (SCFE).

METHODS

The posterior sloping angle (PSA) was measured using lateral radiographs in 67 patients with a unilateral SCFE and in 41 age-matched normal controls. A symptomatic epiphyseal slip was defined as the development of SCFE.

RESULTS

The contralateral PSA in SCFE patients was more widely distributed and significantly larger compared to controls (15.0° vs. 9.0°, p < 0.0001). Forty-seven hips (70.1%) had a PSA of greater than 12.8°, which was +2SD of the control hips. Of the 65 hips excluding the two cases with prophylactic pinning, 11 hips (16.9%) eventually developed a contralateral SCFE during adolescence and their PSA at the initial visit was significantly larger compared to patients without a contralateral SCFE (18.0° vs. 14.3°, p < 0.005) with a cutoff value of 19°.

CONCLUSIONS

These findings suggested the possibility of bilateral hip involvement in SCFE patients. Hips with greater degrees of PSA (> 19°) are likely to become symptomatic.

A new navigation-based technique for lateral distalizing condylar osteotomy in patients undergoing total knee arthroplasty with fixed valgus deformity

PURPOSE

In a prospective, consecutive study, a navigation-based technique for calculating the sliding distance of the lateral epicondyle prior to osteotomy in TKA surgery of fixed valgus deformity has been developed, and early results have been evaluated.

MATERIALS AND METHODS

Twenty-seven knees with a fixed valgus deformity undergoing TKA received this new treatment. Clinical scores and radiograph evaluation were performed preoperatively and 1-year postoperatively. Static and dynamic kinematic data were obtained from navigation at the beginning and at the end of surgery.

RESULTS

The calculated amount of sliding distance varied between 5 and 16 mm. No complications regarding this technique occurred. All clinical scores showed a significant improvement, and radiological evaluation showed a correction of all parameters in 100 % of patients.

CONCLUSION

With this navigation-based technique, it is possible to calculate the amount of sliding distance prior to osteotomy and obtain excellent early results. All axes have been corrected completely, and flexion and extension gaps were balanced. No specific complications of this technique have occurred so far.

LEVEL OF EVIDENCE

II.

The fate of hips that are not prophylactically pinned after unilateral slipped capital femoral epiphysis

BACKGROUND

The indications for prophylactic pinning of the contralateral hip after unilateral slipped capital femoral epiphysis (SCFE) remain controversial in part because the natural history of the contralateral hip is unclear.

QUESTIONS/PURPOSES

We therefore determined (1) the incidence of contralateral slips in patients with unilateral SCFE, (2) the rate of subsequent corrective surgery, and (3) the Harris hip score (HHS) and VAS pain score for hips that sustained a contralateral slip after unilateral pinning.

METHODS

We retrospectively reviewed 226 patients with unilateral SCFE at initial presentation between 1965 and 2005; of these, 133 met our inclusion criteria and were followed at least 2 years. Latest followup included examination and radiographs for 52 patients and HHS (without radiographs) and VAS pain score for 81 hips. Minimum followup was 2 years (median, 13 years; range, 2-43 years).

RESULTS

Of the 133 patients at risk for a subsequent slip, 20 patients developed a contralateral slip (15%). One patient developed avascular necrosis requiring arthroplasty, and another patient had a mild contralateral slip with disabling pain. For the 15 patients with contralateral slips and scores available, the mean HHS was 90 (range, 49-100) and the mean VAS pain score was 20 of 100. Six found the contralateral hip painful.

CONCLUSIONS

The contralateral slip sustained by the majority of patients was for the most part mild. However, nearly 1/3 of the contralateral slipped hips were painful. One patient has severe pain, and a second required THA for avascular necrosis after an unstable slip. These may have been preventable by prophylactic pinning.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

[Slipped capital femoral epiphysis]

Slipped capital femoral epiphysis (SCFE) is characterized by displacement of the capital femoral epiphysis from the metaphysis through the physis. The term is confusing, because the metaphysis moves upward and outward while the epiphysis remains in the acetabulum. The SCFE is considered stable when the child is able to walk with or without crutches, and it is considered unstable when the child cannot walk with or without crutches. Patients with SCFE present with pain in the groin, knee and limp. The current treatment of stable SCFE is in situ stabilization with a single screw.

Patellar resurfacing versus nonresurfacing in total knee arthroplasty: a meta-analysis of randomised controlled trials

PURPOSE

Patella resurfacing or nonresurfacing in total knee arthroplasty remains controversial. The aim of this study was to evaluate the efficacy of patellar resurfacing through an evaluation of the current literature.

METHODS

We carried out a meta-analysis of randomised controlled trials comparing total knee arthroplasties performed with and without patellar resurfacing. Outcomes of reoperation, anterior knee pain and knee scores were analysed.

RESULTS

Fourteen trials assessing 1,725 knees were eligible. The absolute risk of reoperation was reduced by 4 % (95 % confidence interval, 2-6 %) in the patellar resurfacing arm (between-study heterogeneity, P = 0.05, I(2) = 42 %), implying that one would have to resurface 25 patellae (95 % confidence interval, 17-50 patellae) in order to prevent one reoperation. There was no difference between the two groups in terms of anterior knee pain, knee pain score, Knee Society score and knee function score. But in the studies followed up for a mean time of not less than five years, a difference was found between the two arms in Knee Society scores (RR = 2.14, 95 % confidence interval, 0.76-3.52; P = 0.002).

CONCLUSIONS

The available evidence indicates that patellar resurfacing reduces the risk of reoperation after total knee arthroplasty. Patellar resurfacing patients may make a difference in long-term follow-up (five or more 5 years) of Knee Society scores. In other aspects, the benefit of patellar resurfacing is limited. Additionally, more carefully and scientifically designed randomised controlled trials are required to further prove the claim.

Clinical results associated with changes of posterior tibial slope in total knee arthroplasty

Purpose

The purpose of this retrospective study is to investigate the effect of posterior tibial slope (PTS) on clinical results in total knee replacement arthroplasty (TKA).

Materials and Methods

We analyzed 801 knees in 768 patients who underwent TKA using a cruciate-retaining prosthesis for osteoarthritis from July 2003 to July 2009. PTS was measured on simple X-ray films and patients were divided into 5 groups, according to the change in PTS that was calculated by subtracting the preoperative from the postoperative PTS: group 1, >3°; group 2, 3° to 1°; group 3, 1° to -1°; group 4, -1° to -3°; and group 5, <-3°. We analyzed the correlations between the change in PTS and clinical results, such as Knee Society knee score, Knee Society functional score, Feller patella score, Kujala score, visual analog scale score, range of motion, and complications.

Results

There was no statistically significant intergroup difference; however, Feller patella score and Kujala score were significantly different in groups 2 and 3. There were no complications, such as progressive loosening of implants, fractures of polyethylene inserts and wears.

Conclusions

Clinically meaningful improvement was observed in all patients after TKA. Groups 2 and 3 (3° to -1°) showed significant improvement compared to the other groups.

Prediction of contralateral slipped capital femoral epiphysis using the modified Oxford bone age score

BACKGROUND

The purpose of the present study was to determine whether the modified Oxford bone score can be used as a predictor for the risk of developing contralateral slipped capital femoral epiphysis (SCFE) in children who present with a unilateral slip.

METHODS

We identified 260 patients treated for unilateral SCFE between 1980 and 2002 and followed them up to skeletal maturity or until development of contralateral slip. Exclusion criteria included patients with endocrine or metabolic disorder, Down syndrome, and those with radiographs inadequate to determine the modified Oxford bone score. The initial radiographs were given a score ranging from 16 to 26. Statistical analysis was used to determine whether the modified Oxford bone score was predictive of future development of contralateral slip. A linear regression model was used to estimate the probability of future development of a contralateral slip as related to the modified Oxford bone score.

RESULTS

Of the 260 patients, 64 (24%) developed a contralateral slip, at an average of 10 months after initial presentation. Race, sex, age, and weight at initial presentation were not predictive of the development of contralateral slip. The modified Oxford score and a triradiate score of 1 were found to be significant (P<0.0001) predictors, with the modified Oxford score a better overall predictor.

CONCLUSIONS

The modified Oxford bone age score is the best predictor of the risk of development of a contralateral SCFE in patients presenting with a unilateral slip. Controversy exists regarding prophylactic pinning of a normal hip in patients presenting with unilateral SCFE. The benefits of prophylactic pinning must outweigh risk. This study provides probability data for predicting a contralateral slip based on the modified Oxford bone maturity score that can be shared with families and allows physicians to decide their threshold for prophylactically pinning the contralateral hip in patients presenting with a unilateral slip.

LEVEL OF EVIDENCE

Therapeutic level IV, Case series.

Patellofemoral arthroplasty, where are we today?

PURPOSE

Patellofemoral arthroplasty remains controversial, primarily due to the high failure rates reported with early implants. Numerous case series have been published over the years detailing results of various first- and second-generation implants. The purpose of this work is to summarize results published to date and identify common themes regarding implants, surgical techniques, and indications in order to maximize results of future procedures.

METHODS

A comprehensive review of the MEDLINE database was carried out to identify all clinical studies related to patellofemoral arthroplasty.

RESULTS

First-generation resurfacing implants were associated with relatively high failure rates in the medium term. Second-generation implants, with femoral cuts based on TKA designs have yielded more promising medium-term results. Surgical indications are specific and must be carefully followed to minimize poor results. Short-term complications are generally related to patellar maltracking, while long-term complications are generally related to progression of osteoarthritis in the tibiofemoral joint. Implant loosening and polyethylene wear are rarely reported. Short-term results are favourable for new technology including custom implants and computer navigated surgery.

CONCLUSIONS

Overall, recent improvements in implant design and surgical techniques have resulted in improvements in short- and medium-term results. More work is required to assess the long-term outcomes of modern implant designs.

LEVEL OF EVIDENCE

IV.

The controversy of patellar resurfacing in total knee arthroplasty: Ibisne in medio tutissimus?

Early arthroplasty designs were associated with a high level of anterior knee pain as they failed to cater for the patello-femoral joint. Patellar resurfacing was heralded as the saviour safeguarding patient satisfaction and success but opinion on its necessity has since deeply divided the scientific community and has become synonymous to topics of religion or politics. Opponents of resurfacing contend that the native patella provides better patellar tracking, improved clinical function, and avoids implant-related complications, whilst proponents argue that patients have less pain, are overall more satisfied, and avert the need for secondary resurfacing. The question remains whether complications associated with patellar resurfacing including those arising from future component revision outweigh the somewhat increased incidence of anterior knee pain recorded in unresurfaced patients. The current scientific literature, which is often affected by methodological limitations and observer bias, remains confusing as it provides evidence in support of both sides of the argument, whilst blinded satisfaction studies comparing resurfaced and non-resurfaced knees generally reveal equivalent results. Even national arthroplasty register data show wide variations in the proportion of patellar resurfacing between countries that cannot be explained by cultural differences alone. Advocates who always resurface or never resurface indiscriminately expose the patella to a random choice. Selective resurfacing offers a compromise by providing a decision algorithm based on a propensity for improved clinical success, whilst avoiding potential complications associated with unnecessary resurfacing. Evidence regarding the validity of selection criteria, however, is missing, and the decision when to resurface is often based on intuitive reasoning. Our lack of understanding why, irrespective of pre-operative symptoms and patellar resurfacing, some patients may suffer pain following TKA and others may not have so far stifled our efforts to make the strategy of selective resurfacing succeed. We should hence devote our efforts in defining predictive criteria and indicators that will enable us to reliably identify those individuals who might benefit from a resurfacing procedure. Level of evidence V.

The Effect of Electrocautery around the Patellar Rim in Patellar Non-Resurfacing Total Knee Arthroplasty

Purpose

The purpose of this study was to evaluate the clinical effect of electrocautery on the reduction of pain in patellar non-resurfacing bilateral total knee arthroplasty.

Materials and Methods

A total of 50 patients were enrolled into this study; all patients had undergone bilateral patellar non-resurfacing total knee arthoplasty at our hospital, between January 2007 to December 2008. The minimum follow-up period was 1 year. The electrocautery of the patellar rim was performed randomly on one side only. The clinical results were evaluated between the electrocautery group and the non-electrocautery group based on measures of anterior knee pain, range of motion, American Knee Society clinical rating score, Feller knee score, Western Ontario and McMaster Universities score, and radiographic analysis.

Results

There were statistically significant differences between preoperative and postoperative status for all parameters. There were no statistically significant differences noted between the electrocautery group and the non electrocautery group for all parameters.

Conclusions

Electrocautery of patellar rim is thought to be less effective in reducing anterior knee pain.

Comparison of patellar retention versus resurfacing in LCS mobile-bearing total knee arthroplasty

PURPOSE

The aim of this retrospective study was to compare clinical outcomes of total knee arthroplasty (TKA) with and without patellar resurfacing using the Low Contact Stress (LCS) mobile-bearing prosthesis in 275 osteoarthritic knees (199 patients) after a minimum of 7 years of follow-up.

METHODS

Patients were divided into a patellar retention group (132 knees) and a resurfacing group (143 knees), with median follow-up durations of 7.8 years (range, 7-8.5 years) and 8.5 years (range, 7-10.6 years), respectively. The demographics of the two groups were otherwise matched. The patelloplasty was performed for patellar retention. Patients were evaluated by a blinded, independent observer using Feller's patellar score, the Knee Society score, patient satisfaction, patellar tilt, and lateral displacement.

RESULTS

Patellar resurfacing was not superior to retention with respect to any of the measured variables. Eight knees (6.1%) without and 6 (4.2%) with patellar resurfacing had anterior knee pain related to the patellofemoral joint (n.s.). The reoperation rate related to the patellofemoral joint was 0.8% (n = 1) in the retention group compared with 2.8% (n = 4) in the resurfacing group (n.s.). In the 35 patients who underwent bilateral TKA with patellar resurfacing on only one side, there were no significant differences between the two sides in subjective preference, clinical scores, or functional ability.

CONCLUSIONS

The clinical and radiographic outcomes of TKA with the LCS mobile-bearing prosthesis showed no significant difference between the two groups after a minimum of 7 years of follow-up. The findings in this study suggest that patellar retention with a patelloplasty may be viable as a routine procedure, even in knees with advanced patellofemoral arthritis, if soft tissue balancing and a patella-friendly prosthetic design are properly used.

LEVEL OF EVIDENCE

Therapeutic, retrospective, comparative study, Level III.

The epidemiology and demographics of slipped capital femoral epiphysis

The etiology of slipped capital femoral epiphysis (SCFE) is unknown with many insights coming from epidemiologic/demographic information. A systematic medical literature review regarding SCFE was performed. The incidence is 0.33/100,000 to 24.58/100,000 children 8 to 15 years of age. The relative racial frequency, relative to Caucasians at 1.0, is 5.6 for Polynesians, 3.9 for Blacks, and 2.5 for Hispanics. The average age is 12.0 years for boys and 11.2 years for girls. The physiologic age when SCFE occurs is less variable than the chronologic age. The average symptom duration is 4 to 5 months. Most children are obese: >50% are >95th percentile weight for age with average BMI is 25-30 kg/m(2). The onset of SCFE is in the summer when north of 40°N. Bilaterality ranges from 18 to 50%. In children with bilateral involvement, 50-60% present with simultaneous SCFEs and those who present with a unilateral SCFE and subsequently develop a contralateral SCFE do so within 18 months. The age at presentation is younger for those who present with a unilateral SCFE and later develop a contralateral SCFE. The age-weight, age-height, and height test are useful to differentiate between an idiopathic and atypical SCFE.

Patellar resurfacing in total knee arthroplasty for osteoarthritis: a meta-analysis

PURPOSE

Whether to resurface the patella during a primary total knee arthroplasty remains a controversial issue. The aim of this study was to determine the advantages and disadvantages of patellar resurfacing during total knee arthroplasty for osteoarthritis through an evaluation of the current literature.

METHODS

A meta-analysis of randomized controlled trials comparing patellar resurfacing with nonresurfacing during total knee arthroplasties was performed. The focus of this analysis was on outcomes of reoperation, anterior knee pain and knee scores.

RESULTS

Ten trials assessing 1,003 knees were eligible. The absolute risk of reoperation was reduced by 4% (95% confidence interval, 1-7%) in the patellar resurfacing arm (between-study heterogeneity, P = 0.06, I (2) = 45%), implying that one would have to resurface 25 patellae (95% confidence interval, 14-100 patellae) in order to prevent one reoperation. Only seven trials provided adequate data of anterior knee pain for a quantitative synthesis. On the basis of those seven trials, there was no difference between the two groups in terms of anterior knee pain. Anterior knee pain after total knee arthroplasty could have multiple etiologies such as surgical factors and nonresurfaced patella is not the sole cause of this problem.

CONCLUSION

The available evidence indicates that patellar resurfacing reduce the risk of reoperation after total knee arthroplasty for osteoarthritis. Not resurfacing the patella might be considered a reasonable option, but patients must accept the increased risk of reoperation for which the quantitative evidence-based synthesis is mild. Based on the evidence provided by this study and those previously published ones, the authors do not now resurface the patella as a matter of routine for patients having a primary total knee arthroplasty for osteoarthritis.

Obesity in pediatric orthopaedics

Obesity is a rapidly expanding health problem in children and adolescents and is the most prevalent nutritional problem for children in the United States. Some believe that obesity has become a major epidemic in American children, with the prevalence having more than doubled since 1980. This epidemic has led to a near-doubling in hospitalizations with a diagnosis of obesity between 1999 and 2005 and an increase in costs from $125.9 million to $237.6 million between 2001 and 2005. This article describes some of the orthopaedic conditions commonly encountered in overweight/obese children and adolescents, classically infantile and adolescent tibia vara and slipped capital femoral epiphysis. Also discussed are genu valgum, which has been associated with obesity, and other difficulties encountered in providing orthopaedic care to obese children.

Patellar resurfacing compared with nonresurfacing in total knee arthroplasty. A concise follow-up of a randomized trial

Patellar resurfacing in total knee arthroplasty remains controversial. This study compared the long-term clinical outcomes of total knee arthroplasties performed with and without the patella resurfaced and is an update of a previous report. Eighty-six patients (118 knees) underwent primary total knee replacement and were randomized into two groups: those treated with and those treated without resurfacing of the patella. Outcomes included the scores according to the Knee Society clinical rating system, the scores according to a forty-one-question patellofemoral-specific patient questionnaire, patient satisfaction, global and anterior knee pain scores, radiographic findings, and complications and revisions. Fifty-seven patients (seventy-eight knees) were followed for a minimum of ten years. No significant differences were identified between the two groups in terms of the range of motion, Knee Society scores, satisfaction, global knee pain, or anterior knee pain. The overall revision rates in the original series of 118 knees were 12% in the nonresurfacing group and 9% in the resurfacing group. Seven patients (12%) in the nonresurfacing group and two patients (3%) in the resurfacing group underwent revision for a reason related to a patellofemoral problem. On the basis of these findings, we concluded that, with the type of total knee arthroplasty used in our patients, similar results may be achieved with and without patellar resurfacing.

Resurfacing versus nonresurfacing the patella in total knee arthroplasty: a critical appraisal of the available evidence

A systematic literature search for evidences comparing treatment effect and harm of resurfacing versus nonresurfacing the patella in total knee arthroplasty was conducted and yielded five meta-analysis (MA), one systematic review (SR) and six randomized controlled trials not included in previous MAs/SR. The evidence suggests that patellar resurfacing would reduce the risk of anterior knee pain, as well as the risk of patella-related reoperation. Furthermore, patients not undergoing patella resurfacing would experience more knee pain during stair climbing and be less satisfied with surgery. No significant difference in range of motion can be expected with or without patellar resurfacing. Importantly, methodological limitations were observed in all retrieved studies and evidences about potential adverse events related to patellar resurfacing are presently undetermined.

Chondrolysis, osteonecrosis, and slip severity in patients with subsequent contralateral slipped capital femoral epiphysis

BACKGROUND

Prophylactic pinning of the radiographically and clinically normal contralateral hip in a patient with a unilateral slipped capital femoral epiphysis remains controversial. The purpose of this study was to identify the prevalence of chondrolysis and osteonecrosis and the degree of slip severity in contralateral hips with a subsequent slipped capital femoral epiphysis to determine whether the outcome or complications on the contralateral side were greater than the risks of prophylactic pinning.

METHODS

The medical records of the patients operated on between 1993 and 2003 at a single hospital for treatment of a slipped capital femoral epiphysis were retrospectively evaluated. The severity and the chronicity of the slips were graded. Only children who initially had had a unilateral slip and had been followed for a minimum of twenty-four months or until skeletal maturity were included in the analysis for detection of a subsequent contralateral slip. Patients with more than twelve months of follow-up were included in the analysis for detection of osteonecrosis and chondrolysis.

RESULTS

Two hundred and twenty-seven patients had a unilateral slipped capital femoral epiphysis at the time of the primary admission. A subsequent slip developed in the contralateral hip of eighty-two children (36%) within a mean of 6.5 months. Eighteen of the contralateral slips were of moderate or severe severity, with a potential for a poor outcome due to a risk of osteoarthritis in the future. Osteonecrosis or chondrolysis, each an established complication with a poor long-term prognosis, developed in five of the patients with a subsequent contralateral slip.

CONCLUSIONS

The high prevalence of a subsequent contralateral slip (36%) and the potential complication (high slip severity) and established complications (osteonecrosis and chondrolysis) related to the contralateral slip indicate that prophylactic pinning of the contralateral hip in a patient with a unilateral slipped capital femoral epiphysis is safer than and preferable to observation and symptomatic treatment.

Posterior sloping angle of the capital femoral physis: interobserver and intraobserver reliability testing and predictor of bilaterality

The management of the contralateral hip after unilateral slipped capital femoral epiphysis (SCFE) is controversial. The aims of this study were to assess the interobserver and intraobserver reliability of the posterior sloping angle (PSA) as described by Barrios et al (J Pediatr Orthop. 2005;25:445-449) and whether it can be used as a predictor of need for prophylactic pinning of the contralateral hip. The PSA was measured by 4 different surgeons on 2 separated occasions in 47 unaffected contralateral hips after unilateral SCFE. The interobserver intraclass correlation coefficient (ICC) was 0.83 (excellent) for the first set of measurements and 0.74 (fair to good) for the second set of measurements. Measurement of the intraobserver ICC revealed an excellent agreement (ICC > 0.75) in 3 of the 4 surgeons and fair to good agreement in 1 of the surgeons (ICC between 0.4 and 0.74). Comparison of the PSA measurements of the first author (M.Z.) with a control group of 20 hips revealed that the PSA was significantly higher (P < 0.05) in the group of patients that eventually had a contralateral slip when compared with the PSA of patients in the study group who did not slip and with normal hips in the control group. Patients with contralateral SCFE that did not slip had a significantly higher PSA (P < 0.05) when compared with normal individuals. A PSA of 14.5 degrees or more is recommended for prophylactic pinning of the contralateral hip. The number needed to treat (NNT) at this cut off to avoid 1 future slip was calculated to be 1.9.

Slipped capital femoral epiphysis: current concepts

Slipped capital femoral epiphysis is a common hip disorder in adolescents, with an incidence of 0.2 (Japan) to 10 (United States) per 100,000. The etiology is unknown, but biomechanical and biochemical factors play an important role. Symptoms at presentation include pain in the groin, thigh, or knee. Ambulatory patients also may present with a limp. Nonambulatory patients present with excruciating pain. The slipped capital femoral epiphysis is classified as stable when the patient can walk and unstable when the patient cannot walk, even with the aid of crutches. Because the epiphysis slips posteriorly, it is best seen on lateral radiographs. The treatment of choice for stable slipped capital femoral epiphysis is single-screw fixation in situ. This method has a high probability of long-term success, with minimal risk of complications. In the patient with unstable slipped capital femoral epiphysis, urgent hip joint aspiration followed by closed reduction and single- or double-screw fixation provides the best environment for a satisfactory result, while minimizing the risk of complications.